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VFSMOD-W - Agricultural and Biological Engineering

1. Spring Cover Soil loss ratio for cropstage period and canopy cover Cover Crop Sequence Resi After No and manmagement due Plant F SB 1 2 3 80 90 96 4Lf LB Corn after C GS G or COT In Meadowless Systems 1 Rdl sprg TP 4500 31 55 48 38 20 23 2 3400 36 60 52 41 24 20 30 3 2600 43 64 56 43 32 25 21 37 4 2000 51 68 60 45 33 26 22 47 5 Rdl fall TP HP 44 65 53 38 20 6 GP 49 70 57 41 24 20 7 FP 57 74 61 43 32 25 21 8 LP 65 78 65 45 32 26 22 9 RdR sprg TP HP 66 74 65 47 22 568 10 GP 67 75 66 47 27 23 62 11 FP 68 76 67 48 35 27 69 12 LP 69 77 68 49 35 74 13 RdR fall TP HP 76 82 70 49 22 14 GP 77 83 71 50 27 23 15 FP 78 85 72 51 35 27 16 LP 79 86 73 52 35 17 Wheeltrack pl RdL TP 4500 x i 31 27 25 E 18 26 18 3400 36 32 30 22 18 30 19 2600 43 36 32 29 24 19 37 20 2000 51 43 36 31 24 20 47 21 Deep offset disk or plow 4500 10 45 38 34 20 23 22 3400 10 52 43 37 24 20 30 23 2600 5 57 48 40 32 25 21 37 24 2000 61 51 42 33 26 22 47 25 No till plant in crop resi 6000 95 2 2 2 2 14 26 due 6000 90 3 3 3 3 14 27 4500 80 5 5 5 5 15 28 3400 70 8 8 8 8 6 19 29 3400 60 12 12 12 12 9 8 23 30 3400 50 15 15 14 14 11 9 27 31 2600 40 21 2
2. Part I VFSMOD W Model Documentation 1 Introduction Runoff carrying sediment from nonpoint sources has long been recognized as a major pollutant of surface water Sediment bound pollutants such as phosphorous and some pesticides are also a major pollution concern Several management practices have been suggested to control runoff quantity and quality from disturbed areas One such management practice is vegetative filter strips VFS which can be defined as Dillaha et al 1989 areas of vegetation designed to remove sediment and other pollutants from surface water runoff by filtration deposition infiltration adsorption absorption decomposition and volatilization These bands of planted or indigenous vegetation separate a water body from a land area that could act as a nonpoint pollution source Vegetation at the downstream edge of disturbed areas may effectively reduce runoff volume and peak velocity primarily because of the filter s hydraulic roughness and subsequent augmentation of infiltration Decreasing flow volume and velocity translates into sediment deposition in the filter due to a decrease in transport capacity Wilson 1967 Barfield et al 1979 and Dillaha et al 1986 reported that grass filter strips have high sediment trapping efficiencies as long as the flow is shallow and uniform and the filter is not submerged Researchers Dillaha et al 1989 Parsons et al 1991 have found that the filter length
3. 4 De duration of rainfall excess PEU lt gt Runoff volume 1p Peak runoff P Time t t b lt gt Figure 10 Hydrograph quantities used in calculation of time shifting We can now calculate the duration of the rainfall excess De as De D ti 23 In this option 2 the corrected time to peak of the hydrograph can be obtained from the ordinate of the unit hydrograph as tp 0 127481 Q A qp 24 A time shifting is needed in the hydrograph to match the rainfall as toff tp tp 25 and all the hydrograph times will be corrected as t t toff 26 An example showing the calculations for both options 1 and 2 is shown bellow Versions of UH after 0 7 implement Option 1 since it produces runoff after the peak of the hyetograph as in observed natural events see Figure 11 Part I VFSMOD W Model Documentation 20 0 01 Option 1 gt toff ti 0 008 UH based Option 2 gt toff tp tp Rainfall 54109 0 006 o e E 0 004 1 10 0 002 0 1 531075 0 5000 1 104 1 5 10 2 104 Time s Figure 11 Time shifting of hydrographs to match the storm 3 3 Incoming sediment load calculation 3 3 1 Universal Soil Loss Equation USLE The Universal Soil Loss Equation USLE was developed in the 1950 s by Wischmeier and Smith 1978 as an empirical equation to address erosion from areas characterized by overland flow The equation was derived
4. Courant Number CR 0 5 0 8 9 Maximum Iterations MAXITER 350 Output Element Information 1 fIELOUT 1 or 0 Save Continue Editing Save and Close Close Window Help LABEL FWIDTH width of the strip m VL length of the filter strip m a label max 50 characters to identify the program run Part III VFSMOD W User s Manual 75 THETAW CR MAXITER NPOL IELOUT KPG NPROP SX l RNA I SOA l number of nodes in the domain integer must be an odd number for a quadratic finite element solution but the program checks and corrects if needed time weight factor for the Crank Nicholson solution 0 5 recommended Courant number for the calculation of time step from 0 5 0 8 recom mended See Tips for running the model on page 50 integer maximum number of iterations alowed in the Picard loop integer number of nodal points over each element polynomial degree 1 Recommended value 3 See Tips for running the model on page 50 integer flag to output elemental information 1 or not 0 integer flag to choose the Petrov Galerkin solution 1 or regular finite element 0 Recommended value 1 See Tips for running the model on page 50 integer number of segments with different surface properties slope or roughness real X distance from the beginning on the filter in which the segment of uniform surface properties ends m Manning s roughness for ea
5. Part III VFSMOD W User s Manual 78 integer incoming sediment particle class according to the USDA NPART 1975 particle classes NPART Particle class Diam range cm d cm V cm s cm s 1 Clay 0 0002 0 0002 0 0004 2 60 2 Silt 7 0 0002 0 005 0 0010 0 0094 2 65 3 Small aggregate 0 0030 0 0408 1 80 4 Large aggregate 0 0300 3 0625 1 60 5 Sand 0 0050 0 2 0 0200 3 7431 2 65 6 Silt 2 0 0002 0 005 0 0029 0 0076 2 65 T User selected DP model SG of particles from incoming sediment with diameter gt 0 0037 cm COARSE coarse fraction that will be routed through wedge unit fraction i e 100 1 0 CI incoming flow sediment concentration g cm POR porosity of deposited sediment unit fraction i e 43 4 0 434 DP sediment particle size diameter d5o cm read only if NPART 7 SG sediment particle density s g cm read only if NPART 7 S 5 Storm Hyetograph irn The hyetograph input files can be manually entered or generated using the UH program See the UH program documentation for further information Storm Hyetograph irn nputsXsemple im Rainfall Rate m s 000001693 Number of Rainfall 12 Periods NRAIN 000006773 00001101 00001847 00001847 a0 0 0 0 Maximum rainfall intensity for the storm RPEAK m s 1847E 04 EU E v Inse
6. 1 3 INI A B X XM X0 Q0 QM SSE NODEX The main program matrices are set to zero before the beginning of the simulation 1 4 GRASSIN ICOARSE COARSE LISFIL This subroutine reads in the main parameters of the sediment sub model calculates some of the additional parameters needed and echo this information into the output files This is done in the following steps a read parameters from the igr and isd input files b choose particle diameter cm fall velocity cm s and particle density g cm from the internal data base or if the particle class is not in the database calculate values using Fair and Geyer method 1954 based on Stokes note all units in SI c if particle is fine d lt 37 mm don t run the wedge part COARSE 0 D0 d output some input values here and leave the rest for the INPUTS subroutine e print heading for tables in output files 1 5 INPUTS N NBAND NRAIN RAIN NBCROFF BCROFEF TE QMAX VL FWIDTH PGPAR VKS NCHK LISFIL This subroutine reads in the main parameters of the overland flow and infiltration sub models calculates some of the additional simulation parameters needed and echo this information into the output files This is done in the following steps a read parameters from the ikw input file assign nodes to the X values for each surface segment and calculate elemental Manning s a s b calculate filter main slope Sc and roughness for sediment calculations c check if N is compatible
7. This modification from the original formula results from the fact that to construct a hyetograph for a duration 24 h the interval should be centered around the steepest part of the curve i e around tpg for each one of the storm types An example of the hyetographs obtained for the different storm types for the event in the included sample file UH in 25mm in 6 hours can be seen in Figure 7 Part I VFSMOD W Model Documentation 13 l IA Il amp I TR ih oe dn Loroa oe a Mj Ifa Ifa Ifa Ifa gp gj gp og DEEP i il ik k 0 1 2 3 4 5 6 Time h Figure 7 Rainfall hyetographs generated for different storm types 3 2 Generation of Runoff Hydrographs 3 2 1 Computation of Total Runoff using NRCS Curver Number method SI units Runoff from the source area is computed using the NRCS SCS Curve number method USDA NRCS 1984 _ P 0 25 Q P 0 85 a1 where Q total runoff in cm P total precipitation in cm and P gt 0 2S S represents the antecedent moisture and is computed by _ 25400 CN S 254 12 where CN curve number for the source area The initial abstraction is assumed to be a 0 2 S Tables for selecting the curve number CN are given in Appendix 3 of this manual see also NRCS 1984 In the case of multiple land uses a composite CN can be derived using a weighted average of the respective CN based on the land use areas As in the original derivation of the method Q is s
8. Vieux B E V F Bralts L J Segerlind and R B Wallace 1990 Finite element watershed modeling one dimensional elements J Water Resour Planning and Mgmt Div ASCE 116 6 803 819 Williams J R 1975 Sediment yield prediction with the Universal equation using runoff energy factor In Present and prospective technology for predicting sediment yields and sources ARS S 40 USDA Agricultural Research Service ppp 244 252 Wilson B N B J Barfield and I D Moore 1981 A Hydrology and Sedimentology Watershed Model Part I Modeling Techniques Technical Report Department of Agricultural Engineering University of Kentucky Lexington Wilson L G 1967 Sediment removal from flood water by grass filtration Transactions of ASAE 10 1 35 37 Wischmeirer W H C B Johnson and B V Cross 1971 A soil erodibility nomograph for farmland and construction sites Journal of Soil and Water Conservation 26 5 189 193 Part I VFSMOD W Model Documentation 38 Wischmeirer W H and D D Smith 1978 Predicting rainfall erosion losses a guide to conservation planning Agriculture Handbook No 537 USDA Washington DC 58 pp Wolfram S 1999 The Mathematica Book 4th edition Cambridge Univ Press Woolhiser D A 1975 Simulation of unsteady overland flow In Unsteady Flow in Open Channels Vol II Ed K Mahmood and V Yevjevich 485 508 Fort Collins Water Resources Woolhiser D A R E Smith and D C Goodr
9. The non linearity of the equation q q h is taken care of by using the Picard iterative scheme inside every time step lagging 2 3 of the power of A in q 5 3 2 3 m 1 m 1 for the iteration level m such as A thi b h 6 In this program the core of the time step solution is taken care of following this steps 1 Form the system matrix A of constant coefficients 2 Perform LUD decomposition over this matrix A 3 Form the system matrix BM of constant coefficients 4 Form r h s of equation vector b BM x for each time step 5 Solve for A b to get a x for that time step 6 Repeat 4 amp 5 until convergence of that time step 7 Repeat3 amp 6 until completion of desired number of time steps The transport model supplies information to build the BM and b for each time step Part I VFSMOD W Model Documentation 9 dt The general procedure is structured into subroutines as illustrated in the next diagram p p FACTOR I k UPDATE NNNM MODIFY SOLVE Picard Iteration hc EG lt OCF EINSTEIN STEP3 Only POINTS a 100 times GRASSED KWWRITE o OUTMASS Figure 5 VFSMOD model structure After solving the sediment transport problem for a given time step values of n and S Part I VFSMOD W Model Documentation 10 are selected as nodal values for the finite element grid The parameters are fed back into the hydrology model for the
10. dependent infiltration an accurate description of flow through the filter and changes in flow derived from sediment deposition during the storm event This work presents a design oriented computer modeling system VFSMOD W The MS Windows32 graphical user interface GUI integrates the numerical model VFSMOD a utility to generate inputs for the model based on readily available NRCS site characteristics UH and uncertainty analysis of sensitivity and design menu driven components VFSMOD the core of the design system is a model to study hydrology and sediment transport through vegetative filter strips The model combines the strength of a a numerical submodel to describe overland flow and infiltration b the University of Kentucky s algorithm developed specifically for the filtration of suspended solids by grass This model formulation effectively handles complex sets of inputs similar to those found in natural events The improvements of this combined model over the GRASSF or SEDIMOT II models are the inclusion of a state of the art description of flow through the filter b changes in flow derived from sediment deposition c physically based time dependent soil water infiltration d handling of complex storm pattern and intensity and e varying surface conditions slope and vegetation along the filter VFSMOD UH and additional components are described in this Part I from a theoretical and modelling structure perspective The use
11. 934 463 146 078 460 877 35 639 36 463 36 463 15 371 T1877 9 460 078 146 463 934 509 1158 862 608 388 194 021 867 728 BPO ONDA GAA Wao 4X 4X 4X AA OO ODN 600 mm 600 mm 463 mm 927 mm h RAINFALL ENERGY FACTOR R FOR EROSION CALCULATIONS a Foster et al 1977 E 3738 632 ft tonf acre 25 049 MJ ha volro 63 323 mm qpeak 46 011 mm h Factors in Rm Rst 182 695 Rro 226 905 Rm Foster 170 764 N h b Williams 1975 Watershed area 0 500 ha V 316 613 m3 Qp 0 064 m3 s Rw Williams 97 514 N h c GLEAMS daily CREAMS Rain 102 60 mm R GLM 64 79 From Gleams Wischmeirer R GLM 110 27 N h Converted to Metric ERODIBILITY K AND PARTICLE SIZE SELECTION Table for computing Ksoil from GLEAMS and KINEROS i Soil Type Sand Silt Tex F Str PF Per F D50 Part II VFSMOD and UH User s Manual 63 1 Clay 20 30 0 01287 0 0650 0 075 235 2 Silty clay 10 45 0 01870 0 0650 0 075 24 3 Sandy clay 50 10 0 01714 0 0650 0 075 66 4 Silty clay loam 154 50 0 02606 0 0650 0 050 25 5 Clay loam 35 30 0 02360 0 0650 0 050 18 6 Sandy clay loam 55 20 0 02778 0 0650 0 050 91 Zo SAIE 5 25 0 05845 0 0650 0 025 19 8 Silt loam 20 60 0 04259 0 0650 0 025 273 9 Loam 45 35 0 03618 0 0325 0 025 335 10 Very fine sandy loam 60 25 0 03877 0 0350 0 000 354 11 Fine sandy loam 60 25 0 03205 0 0000 0 000 80 12 Sandy loam 60 25 0 02549 0 0325 0 000 98 13 Coarse sandy
12. Area of the upstream portion in ha storm type 1 I 2 II 3 HI 4 Ia storm duration h Length of the source area along the slope m Slope of the source area expressed as a fraction See Table for Acceptable Soil Types Soil Erodibility If K 0 then K is computed based on texture and organic matter See REF C factor See Table in Appendix 3 P factor See Table in Appendix 3 Part II VFSMOD and UH User s Manual 60 leroty 1 Select the method to compute the storm R factor in MUSLE not present or 1 selects Foster s Method 2 selects Williams method and 3 selects the CREAMS GLEAMS method The program produces two output files that summarize the program execution In this case these are sample2 out and sample2 hyt The sample2 out file contains a printout of the input data along with the runoff hydrograph and a summary The sample2 hyt file contains the information about the rainfall hyetograph along with the outputs related to the erosion from the storm From these results the input files for VF SMOD sample2 iro sample2 irn and sample2 isd are also automatically created in the output directory file sample2 out File output sample2 o ut UH v1 06 3 2002 HYDROGRAPH CALCULATION FOR WATERSHED SCS METHOD Inputs Storm Rainfall 80 00 mm SCS storm type II Storm duration 6 0 h SCS Curve number 72 0 Watershed area 5 00 ha Maximum flow path length 100 00 m Average slope o
13. sediment wedge geometry DEP depth of deposited sediment at lower section of the filter 7 sediment trapping effi ciency The procedure is as follows a if sediment transport capacity g 5 is greater than the fine sediment load fraction Lsim diameter gt 0 0037cm all sediment goes through the wedge to the lower part of the filter ntrcap 1 b if transport capacity is lower than the fine sediment load fraction then the FINE frac tion goes through the wedge and the COARSE fraction is filtered at the wedge c apply open channel flow theory and Einstein s bed load transport equation in B t find df Ry S Newton Raphson method d find advancement of sediment front and outflow concentration d 1 if top of vegetation has not been reached calculate the triangular wedge geometry d 2 trapezoidal wedge geometry e check if strip has been filled up If so set flag NFUP 1 change sediment wedge geom etry to a rectangle of hight H and length VL and bypass GRASSED in the future Also in this case avoid suspended sediment zone calculations f on the assumption that the trapped sediment is uniformly distributed on the bed of the filter s lower section area calculate DEP depth of sediment deposited for that Dt and CDEP as a multiplier to reduce the actual sediment outflow g Wilson et al 1981 g write outputs h update values for next time step 1 24 POINTS N XPOINTS NODEX VBT This program finds a in unifor
14. It also describes the flow rate q velocity V and depth h components throughout the filter for each time step The numerical solution is subject to kinematic shocks or oscillations in the solution Part I VFSMOD W Model Documentation 5 that develop when a sudden change in conditions slope roughness or inflow occurs When linking the kinematic wave and the sediment transport models the soil surface conditions are also changed for each time step further increasing the potential for the kinematic shock problem VFSMOD implements a Petrov Galerkin formulation non standard finite element to solve equations 1 and 2 This solution procedure reduces the amplitude and frequency of oscillations with respect to the standard Bubnov Galerkin method Mufioz Carpena et al 1993a thus improving the model stability and the sediment transport predictions which depend on overland flow values 2 2 Sediment Transport The hydrology model is linked to a model for filtration of suspended solids by artificial grass media developed and later tested for field conditions Barfield et al 1978 1979 Hayes et al 1979 1984 Tollner et al 1976 1977 Wilson et al 1981 It is based on the hydraulics of flow transport and deposition profiles of sediment in laboratory conditions The model presents the advantage of being developed specifically for the filtration of suspended solids by grass ENTRY Wedge Zone I Suspended Load Zone F
15. USLE sese 21 3 3 2 Modifications to USLE to handle storm events sssssseeeeee 23 3 4 Computational Structure of UH 52 n nere ERR USER INCONTRI UR ERREUR 25 3 5 Sensitivity Analysis of VFSMOD ssesesssseseeeeeeeeenee enne nnne eene 26 3 6 Previous Testing and Applications ccccecccescesseescesceeeceseeesecaeessenseceseeseceseeeseeeeseeeeeenees 27 4 Sensitivity and Uncertainty Analysis Procedures for UH and VFSMOD Built In VFSMOD W28 5 Desien Proced ure alo eua enen i Rao M nal eine a a A 30 6 Potential Users and Applications of the Modelling System 32 7 Known Limitations and Applicability of the Models sss 33 7 1 Known Limitations of the Model sse eene enne nennen nnn 33 1 2 Buture Research ios see o E EC OP UC EREE D ERE ERU 33 8 Distribution and Traine ssec etes ed etie ce ae ce iia pl eiecer i e roi tton cedes 34 9 Acki wledgmieints on coq E a ideni EEEE ES 35 10 Referenc s s ose iate a a e apu ease E aE A EAE dia aiiin 36 Table of Contents Part II VFSMOD and UH User s Manual 000 0 eceececccecesssssesesssssssesssesesesenesees 40 1 VESMOD users Manuals jeden dei aso e perduto Me e SE 40 1 1 Obtaining VESMODY serere aient ieget ede rege E egt er ERES 40 1 2 Installing and running VFSMOD ssssesesseseseeeeennen eene nennen nnne 40 1 2 1 Installing for a DOS command pro
16. VFSMOD and UH User s Manual 47 1 4 5 filename igr buffer properties for sediment filtration model 1 4 5 1 Structure of the file SS VN H VN2 ICO 1 4 5 2 Definition SS VN H VN2 ICO spacing of the filter media elements cm filter media grass Manning s n 0 012 for cylindrical media s cm 1 3 filter media height cm bare surface Manning s n for sediment inundated area and overland flow s m 1 3 integer flag to feedback the change in slope and surface roughness at the sediment wedge for each time step 0 no feedback 1 feedback See also additional info on this parameter on the Tips to Run the Model section 1 4 5 3 File example 2 2 0 012 15 0 04 1 1 4 6 filename isd sediment properties for sediment filtration model 1 4 6 1 Structure of the file NPART COARSE CI POR DP SG 1 4 6 2 Definition NPART integer incoming sediment particle class according to the USDA 1975 particle classes NPART Particle class Diam range cm d cm Vr em s y cm s 1 Clay lt 0 0002 0 0002 0 0004 2 60 2 Silt 1 0 0002 0 005 0 0010 0 0094 2 65 3 Small aggregate 0 0030 0 0408 1 80 4 Large aggregate 0 0300 3 0625 1 60 5 Sand 0 0050 0 2 0 0200 3 7431 2 65 6 Silt 2 0 0002 0 005 0 0029 0 0076 2 65 7 User selected DP model SG Part II VFSMOD and UH User s Manual 48 COARSE of particl
17. pa 009 DANZA 0 04 A where T t 12 with t in hours p24 the 24 hour total rainfall in cm For storm durations less than 24 hours the ratio of p t p24 is used to derive the amount of rainfall at time from the total rainfall for the period The computation procedure follows that given by Haan et al 1994 3 1 2 Equations for storm types I amp IA Based on tabulated data Haan et al 1994 pg 48 the fitted equations using Mathematica Wolfram 1999 are e Storm type I 0 1617 3 0163 r 9 995 0 013 0 5129 3 0163 r 9 995 0 013 gt 0 0 5853 0 4511 r 9 995 3 0163 t 9 995 0 013 lt 0 8 2 Py With an Root Mean Square Deviation RMSD 0 0088 and 1 3 363 Part I VFSMOD W Model Documentation 12 e Storm type IA 0 0843 pe 0 3919 1 7 120 3917 7 9601 03567 0 3919 1 7 960 120 39 7 960 0 3567 m 24 With an RMSD 0 0033 and y 1 539 The comparison of fitted vs real values can be seen on Figure 6 fitted IA fitted P Po 0 5 10 15 20 Time hours Figure 6 NRCS storm types fitted by proposed equations To construct hyetographs for any duration D h and storm type equation 3 7 in Haan et al 1994 pg 49 was transformed to _ Pltmigt t D 2 PU tmig D 2 rm 10 Py P t4 D 2 P t D 2 where f is 9 995 for storm type I 7 960 for storm type IA and 12 0 for storm type II and III
18. 100 water weight density g cm3 sediment weight density g cm3 sediment load entering before field deposition gsl g s 1 cm 1 sediment load entering the filter after field depos gsi g s 1cm 1 sediment load entering downstream section gsd g s 1cm 1 sediment load exiting the filter gso g s 1cm 1 filter media height cm Flag O strip is not filled up 1 strip is filled up node number for X1 X2 X3 points sediment class diameter cm sediment class fall velocity cm s sediment class weight density g cm3 porosity of deposited sediment overland flow rate for X1 X2 X3 points cm2 s hydraulic radius of the filter cm hydraulic radius of the filter at B t cm equilibrium slope at B t spacing of the filter media elements cm filter main slope filter length in cm depth averaged velocity at D t cm s depth averaged velocity at B t cm s filter media Manning s n 0 012 for cylindrical media s cm 1 3 Filter Manning s roughness coefficient for bare sediment inundated soil s cm 1 3 Position for the 3 locations where de flow is read from the hydrol ogy model q1 q2 q3 at the 3 last faces of the filter cm X2 XPOINTS 2 cm width of sediment wedge from field edge width of sediment wedge in the field cm height of sediment deposition wedge at the initial triangular stage Part IV VFSMOD Appendices 109 3 APPENDIX 3 Soils and Vegetation data 3 1 Soils data Green Ampt parame
19. 33 21 02 346 90 S siis wee O 80 0 S 43 89 219 457 41 91 210 339 10 666 5468 46 24 92 2589 08 12 31 473 958 O 80 0 10 43 89 219 444 40 25 202 823 19 717 5468 09 24 92 1073 87 5 29 196 924 O 80 0 15 43 69 219 444 38 74 195 956 28 132 5467 53 24 92 839 96 4 28 184 89 O 80 0 20 43 88 219 392 37 32 189 510 36 078 5467 21 24 92 657 30 3 47 12 864 O 100 O 5 61 47 307 345 59 49 298 579 10 700 8803 90 28 65 5559 80 18 62 632 971 O 100 0 10 61 47 307 344 57 81 291 276 19 937 8791 39 20 60 1979 71 4 74 187 948 0 100 0 15 61 47 307 942 56 26 284 559 28 588 8791 58 28 61 1116 91 3 93 127 926 O 100 0 20 61 47 307 952 54 81 279 209 36 803 8791 81 28 60 906 54 3 26 103 905 Sj I insert EditPad Lite 4 5 0 Copyright 1996 2002 Jan Goyvaerts http J www EdtPadiite com Part III VFSMOD W User s Manual 96 11 Troubleshooting vfsmod w As you encounter problems you can e mail us for help assistance In most cases you should send us copies of the files giving problems along with a detailed description so we can recreate the problem You can e mail problems and any suggestions or questions via the web site http www3 bae ncsu edu vfsmod You can also e mail your problems directly to carpena ufl eduor john parsons gncsu edu Cur
20. 33 59 times 61 On moderate slopes 1 1 1 1 1 1 1 0 1 0 1 0 1 1 62 On slopes 1296 1 4 1 4 1 2 1 0 1 0 1 0 1 0 Ridge Plant lines 33 59 times factor of 63 Rows on contour 0 7 0 7 0 7 0 7 0 7 0 7 0 7 Part IV VFSMOD Appendices 120 Spring Cover Soil loss ratio for cropstage period and canopy cover Cover Crop Sequence Resi After No and manmagement due Plant F SB 1 2 3 80 90 96 4Lf LB 64 Rows U D Slope lt 12 0 7 0 7 1 0 1 0 1 0 1 0 1 0 65 Rows U D Slope gt 12 0 9 0 9 1 0 1 0 1 0 1 0 1 0 Till Plant limes 33 59 times factor of 66 Rows on contour 0 7 0 85 1 0 1 0 1 0 1 0 1 0 66 Rows U D slope lt 7 1 0 1 0 1 0 1 0 1 0 1 0 1 0 Strip Till 0 25 of row spacing 68 Rows on contour 4500 60 12 10 9 8 23 69 3400 50 16 14 12 11 19 27 70 2600 40 22 19 17 17 14 12 30 71 2000 30 27 23 21 20 16 13 36 72 Rows U D Slope 4500 60 16 13 11 9 23 73 3400 50 20 17 14 12 11 27 74 2600 40 26 22 19 17 14 12 30 75 2000 30 31 26 21 20 16 13 36 Vari Till 76 Rows on Contour 3400 40 13 12 11 11 22 77 3400 30 16 15 14 14 13 12 26 78 2600 20 21 19 19 19 16 14 34 Corn after WC of ryegrass or wheat stubble WC reaches stemming stage 79 No till pl in killed WC 4000 T li 7 gi 6 m 80 3000 11 11 11 11 9 7 81 2000 15 15 14 14 11 9
21. 8 Rainfall mm and Buffer Length m gt base uh sample20c lis base vfs sampleQc prj 80 8 655 retv CN uhk uhe uhp isoks aRoa isothetai igrss FldROmm FldROm3 VFSROmm VFSROm3 VFSINFm3 FldSEDkg FldSEDconc VFSSEDkg VFSSEDconc SDR RDR 0 72 48 oT 4 788 1 125 2 2 23 03 1151 566 22 97 1149 131 11378 57 10538 32 9 17 926 998 0 65 48 7 6 4 788 1 125 2 2 14 75 737 344 14 65 733 088 6 333 6046 01 8 20 5283 96 7 01 874 994 O 67 48 7 6 4 708 1 125 2 2 16 92 846 082 16 83 842 178 5 981 7358 90 8 70 6570 51 7 80 893 995 O 69 48 7 6 4 788 l 125 2 2 19 24 961 847 19 15 957 820 6 104 8850 20 9 20 8037 12 8 99 908 996 O 71 48 7 6 4 788 1 125 2 2 21 71 1085 634 21 62 1081 559 6 153 10534 94 9 70 9701 96 8 97 921 996 o 73 48 7 6 4 788 1 125 2 2 24 34 1216 834 24 26 1213 802 5 109 12292 37 10 10 11445 35 9 43 4931 998 0 75 48 7 6 4 788 1 125 2 2 27 16 1357 888 27 08 1354 619 5 946 14386 87 10 60 13525 39 9 98 94 998 o 77 48 7 6 4 7866 1 125 2 2 30 08 1503 985 30 02 1501 926 4 136 16548 71 11 00 15123 39 10 07 914 999 o 79 48 s7 6 4 788 1 125 2 2 33 24 1662 017 33 18 1659 850 4 244 18780 59 11 30 16983 22 10 23 904 999 O 81 48 7 6 4 708 1 125 2 2 36 60 1830 102 36 53 1827 523 4 656 21407 38 11 70 19594 29 10 72 315 999 0 83 48 7 6 4 708 1 125 2 2 40 16 2007 972 40 08 2005 109 4 941 23885 81 11 90 21576 43 10 76 903 999 o B5 48 7 6 4 788 1 125 2 2 43 90 2195 140 4
22. 82 1500 20 19 18 18 14 11 Strip till 0 25 space 83 Rows U D slope 4000 13 12 11 11 9 84 3000 18 17 16 16 13 10 85 2000 23 22 20 19 15 12 86 1500 28 26 24 22 17 14 87 Rows on contour 4000 10 10 10 10 8 88 3000 15 15 15 15 12 9 89 2000 20 20 19 19 15 12 90 1500 25 24 23 22 17 14 91 Tp conv seedbed 4000 36 60 52 41 24 20 92 3000 43 64 56 43 31 25 21 93 2000 51 68 50 45 33 26 22 94 1500 6l 73 64 47 35 27 23 Part IV VFSMOD Appendices 121 Spring Cover Soil loss ratio for cropstage period and canopy cover Cover Crop Sequence Resi After No and manmagement due Plant F SB 1 2 3 80 90 96 4Lf LB WC succulent blades 95 No till pl in killed WC 3000 11 11 17 23 18 16 96 2000 15 15 20 25 20 17 97 1500 20 20 23 26 21 18 98 1000 26 26 27 27 22 19 99 Strip till 0 25 row sp 3000 18 18 21 25 20 17 100 2000 21 21 25 27 21 18 101 1500 28 28 28 28 22 19 102 1000 33 33 31 29 23 20 CORN in Sodbased systems No till pl in killed sod 103 3 5 tons hay yld 1 1 1 1 1 1 104 1 2 tons hay yld 2 2 2 2 2 2 2 Strip till 3 5 ton hay 105 50 cover till strips 2 2 2 2 2 4 106 20 cover till strips 3 3 3 3 3 5 Strip
23. C1 C2 Storm type II CODES o co n Ci A C2 feceneeeeeeeecc renee ener feses A a A T RE A See eee ees L 2g g8 B H 02 03 04 0 5 LP G Storm type III e o co u Ci A C2 ib pM A h d A Figure 8 Coefficients predicted by proposed polynomials used in NRCS peak flow calculation Part I VFSMOD W Model Documentation 18 3 2 3 Time correction for hydrograph to match hyetograph 3 2 3 1 Option 1 based on NRCS abstraction method Following the NRCS definition for abstraction and curve number we have P ly F4 Q Precipitaci n instant nea i Lb De Tiempo D Figure 9 Precipitation partition in NRCS method Since we can calculate the initial abstraction as 1a 0 2 S and S 25400 CN 254 19 as shown in out file we could find the time when this initial abstraction ends ti by interpolating in the constructed NRCS 10 min hyetograph hyt file Since the starting time for runoff coincides the time rainfall excess begins a time shifting is needed in the hydrograph to match the rainfall as toff ti 20 and all the hydrograph times will be corrected as t t toff 21 3 2 3 2 Option 2 based on NRCS abstraction and Unit Hydrograph Based on the unit hydrograph by definition the time to peak in the unit hydrograph is defined as see Figure 10 tp tj De 2 0 6 te De 2 22 Part I VFSMOD W Model Documentation 19 O gt Time t p excess
24. Maximum 3 Uniform Minimum and Maximum Part III VFSMOD W User s Manual 92 The tabular information presents the event level outputs and starts on the 14 line Each line contains the results for one of the simulations The columns are retv the return value for that simulation 0 indicates that simulation had no errors CN the curve number input UHk soil erodibility K input UHc crop factor input UHp practice factor input isoks the Green Ampt saturated K input aRoa isothetai Green Ampt initial soil water content and igrss stem spacing input Next the summary outputs for the storm are given These include FlIdROmm and FldROm3 the runoff from the source area field in mm and m3 VFSROmm and VFSROm3 the runoff from the vegetative filter strip area in mm and m3 VFSinfm3 the amount of infiltration in the vegetative filter strip in m3 FIdSEDkg and FldSEDconc the sediment from the source area field in kg and kg L VFSSEDkg and VFSSEDconc the sediment lost from the vegetative filter strip in kg and kg L and SDR the sediment delivery ratio Mass Sediment from VFS Mass Sediment from Field and RDR the runoff delivery ratio Runoff from VFS Runoff from Field arira tite 0 afnixi File Edit Block Convert Options View Help BB 6 H Q o c 3 amp m vss ility distributions O Normal i Lognormal 2 triangular 3 Uniform m m Distribution Paramters Mean
25. North Carolina Piedmont Mufioz Carpena et al 1999 and a Coastal Plain Mufioz Carpena 1993 experimental sites Both sites had grass filter strips mixture of fescue bluegrass and bermuda grass with ratios of field to filter lengths from 4 5 1 to 9 1 The field area had varying slope from 5 10 and the filter strip somewhat less The soil types were Cecil sandy clay loam at the Piedmont site and Rains loamy sand at the Coastal Plain site Parsons et al 1991 In general good agreement was obtained between observed and predicted hydrology and sediment outflow values Some sources of variability were discussed to explain some anomalous events Researchers at the University of Guelph Canada tested the model against field experimental data Abu Zreig et al 1999 2001 They reported good agreement R2 0 9 between model predictions infiltration volume and sediment trapping efficiency and measured values if actual filter flow widths discounting concentrated flow segments are used rather than total filter length Factors affecting sediment trapping in VFS were also studied using VFSMOD in a follow up study Abu Zreig 2001 Recently the program has been used to model the effect of VFS in a small watershed 72 Ha Kizil and Lowell 2002 as well as a component to simulate fecal pathogen filtering from runoff Zang et al 2001 Part I VFSMOD W Model Documentation 27 4 Sensitivity and Uncertainty Analysis Procedures for UH and V
26. Relative Base Sensitivity Part III VFSMOD W User s Manual 89 xt Relative Base Sensitivity Plot for Curve Number Curve Number Source Runoff mm Filter Length 20 m Rain 151 1 mm Base value 75 Range 75 to 95 in increments of 1 Mean Rel Sen 2 362 Relalve Sensilivily Std Dev Rel Sen 0 0598 76 78 80 82 84 85 88 90 92 94 96 Cv Rel Sen 2 5 Curve Number Dismiss Plot Selected Output Relative Sensitivity x Relative Sensitivity Plot for Curve Number Curve Number Source Runoff mm Filter Length 20 m Rain 151 1 mm Base value 5 Range 75 to 95 in increments of 1 Mean Rel Sen 2 122 Relalee Sensilivily Std Dev Rel Sen 0 0521 76 78 80 82 84 86 88 90 92 94 Cv Rel Sen 2 5 Curve Number Dismiss Output Sensitivity Results This output file contains all of the analyses for each of the above graphs and the statistics This is useful for further analyses using other application packages such as spreadsheets Part III VFSMOD W User s Manual 90 9 Uncertainty Analysis Screens Uncertainty analysis can be done on a number of the input parameters for both the UH model and VFSMOD These are done using base values from a specific UH and VFSMOD project Select the input parameters you would like to analyze and leave the others unchecked For each of the selected input parameters select a probability distribution and spec
27. The surface characteristics of the filter were shown as an example in section 7 1 3 Description symbol INPUT Value Units Sediment inflow concentration C CI 03400 g cm Particle size diameter NPART 4 d DP 0 0300 em Particle fall velocity NPART 4 V calculated VF 3 0625 cm s Particle weight density NPART 4 Y SG 1 6000 g cm Part II VFSMOD and UH User s Manual 52 Description symbol INPUT Value Units of coarse particles d gt 0 0037 cm COARSE 100 0 Porosity of deposited sediment POR 43 4 Filter main slope calculated S SC 0 0564 Filter media spacing S SS 2 20 cm Filter media height H H 15 0 em Grass modified Manning coefficient n VN 0 0120 s cm 1 Manning coefficient for bare soil n gt VN 0 04 san 1 Surface changes feedback ICO 1 YES 1 7 2 Outputs 1 7 2 1 Calculated simulation parameters file sample ohy Parameter Symbol Value Units Petrov Galerkin parameters PGPAR 0 0433 0 0031 0 3165 0 1451 Space step DX 0 155 s Time step DT 1 40 Number of elements in system NELEM 28 Number of time steps NDT 2568 Estimated maximum flow rate OMAX 0 000735 m s Estimated maximum flow depth HMAX 0 000735 m Celerity of the wave C 0 08816 0 01389 m s Courant time step DTC 1 753 S Froude number FR 0 143 Kinematic wave number FK 1892 1 7 2 2 Hydrological ou
28. a few computer platforms can also be found at the internet site 1 2 1 Installing for a DOS command prompt window under Windows 9x NT 2000 XP a From the Start Menu Start a Command Prompt DOS window b Change to the drive and directory where you want to install c Create a directory named VFSMOD d Expand the contents of the file vfsmodpc zip This should create the following directory structure vfsmod docs inputs output src uh src vfsm e The executable files VFSM EXE and UH EXE can be found in the parent directory VFSMOD Part II VFSMOD and UH User s Manual 40 f Run the sample case named SAMPLE by typing VFSM SAMPLE at the DOS prompt Please note that the second part of the command issued SAMPLE refers to a set of files located in the subdirectory INPUTS You could run a different problem by selecting a different set of input files with the condition that they are located in the subdirectory INPUTS In this example if you issue the DIR command within the INPUTS directory you should see the following files SAMPLE IGR SAMPLE IKW SAMPLE IRN SAMPLE IRO SAMPLE ISD SAMPLE ISO After you execute the command you should see a screen as follows e d Ce R Q eG e e ge egg QAQ Q e e e e ae e e d eee CEE 3 2002 v1 06 R Munoz Carpena J E Parsons U of Florida USA NCSU S USA carpena ufl edu john _parsons ncsu edu PROGRAM TO CALCULATE OVERLAND FLOW AND SEDIMENT FILTRATION THROUGH A VEG
29. a keyword denoting the type of input and output file and the filename A project file sample prj for the sample inputs in UNIX and Windows 9x NT 2000 XP contains the following line Part II VFSMOD and UH User s Manual 42 UNIX ikw inputs sample ikw igr inputs sample igr im inputs sample irn iro inputs sample iro isd inputs sample isd iso inputs sample iso ogl output sample og1 og2 output sample og2 ohy output sample ohy osm output sample osm osp output sample osp Windows 9x NT 2000 XP ikw inputs sample ikw igr inputs sample igr im inputs sample irn iro inputs sample iro isd inputs sample isd iso inputs sample iso og1 output sample og1 og2 output sample og2 ohy output sample ohy osm output sample osm osp output sample osp The project file in this example sample prj would be saved in the VFSMOD directory where the executable vfsm or VFSM EXE is To execute the model with the project file the fo llowing would be entered vfsm sample prj In this example the input files would be read from the inputs subdirectory and the output files would be created in the output subdirectory In general the project file contains all of the keywords which are Inputs Outputs igr ikw irn iro isd iso buffer properties for the sediment filtration submodel parameters for the overland flow solution storm hyetograph storm hydrograph from the source area sediment properties for the sed
30. as the modified USLE or MUSLE The units of soil loss for this version are Mg for the total watershed area and not per unit area as in the original USLE This assumes that the soil erodibility K units are Mg h ha N 3 4 Computational Structure of UH The program UH generates the necessary inputs from the upslope source area for vfsmod The inputs for UH are discussed in the User s Manual along with a sample input and data set Figure 12 shows the computation structure of UH First the input data describing the source area is read Next UH computes the total runoff from the source area using the SCS Curve Number method The time of concentration peak runoff rate and time of peak is computed by the SCS TR55 method Next SCS unit hydrograph theory is used to estimate the runoff hydrograph An idealized rainfall hyetograph is generated from the SCS storm type MUSLE is then used to estimate the sediment loss from the source area for the storm The sediment loss is partitioned into silt and clay based on the soil particle distribution in the top soil The average concentration in runoff then estimated based on the total runoff and distribution of soil particles in the sediment loss Finally the results are used to create input files for vfsmod These files include data for the hyetograph the runoff hydrograph and sediment loss Part I VFSMOD W Model Documentation 25 Read Input Data for Source Area Calculate Runoff by SCS Met
31. changing the output file names Part III VFSMOD W User s Manual 74 detailed time series describing the sediment transport and deposition within the buffer detailed information on the singular points defined in the theory section of the manual detailed outputs on the inflow and outflow hydrographs detailed summaries of the water and sediment balance final geometry of the filter overall summary of filter performance with comparisons between the source area and filter Inputs Outputs buffer properties for the sediment 0g7 igr filtration submodel parameters for the overland flow og2 ikw solution irn X storm hyetograph ohy storm hydrograph from the source iro area osm sediment properties for the sediment Osp isd filtration submodel soil properties for the infiltration iso submodel 5 1 Overland Flow Inputs ikw at vfsm Editing E vfsmod w combo2 testgui inputs samplejkw O x Overland Flow Properties file ikw inputsXsample ikw Simulation Title Units g8 u183 31 r Buffer Dimensions Buffer Length m VL 8 655 Width of the Strip m PWIDTH 3 View Edit Buffer Segment Properties slope roughness Kinematic Wave Numerical Solution Paramteters Number of Nodes in Solution Domain N 57 Number of Element Nodal Points NPOL 3 3 E Time Weight Factor THETAW 0 5 Petrov Galerkin Solution Regular Finite Element KPG 1 recommended or 0
32. contains a summary of the most relevant input parameters and output results including a sediment and water balance the sediment trapping efficiency of the filter for the simulation case and the final geometry of the filter e filename osp Summary of the filter performance parameters and comparisons between source and filter areas 1 6 Tips for running the model Here are some suggestions to running the model and answers to potential problems a The finite element model becomes unstable or blows up This is due to a rapid change in boundary conditions quick slope and or roughness changes along the filter or inputs severe changes in rainfall intensity and or inflow from the adjacent field in your inputs For this type of conditions the kinematic wave formulation leads to a behavior termed kinematic shock The model s Petrov Galerkin PG finite element formulation was developed to improve the quality of the solution for these type of special sharp front problems and generally overcomes the instability problem Mufioz Carpena et al 1993b The time step is calculated based on a target Courant number CR for the simulation ikw file and an estimate of the less favorable conditions maximum incoming hydrograph peak flow and rainfall intensity In a few cases due to the dynamic nature of the problem this is not a good estimate and the simulation will become unstable or even blow up This can be avoided by lowering the CR at the exp
33. function values b 2 get the value for each element of the array 1 9 SHAPE XIS PSI DPSI WF PGPAR Calculate the values of the weighting and basis functions PSI and their derivatives DPSI with respect to the master element coordinates at a specified value of XIS A typical ele ment x X consisting of k 1 nodes x X 4 is always normalized into the master element 1 1 by the transformation over a typical element x x and there exist k 1 element shape functions PSI each is a polynomial of degree k The type of shape func tion used linear quadratic modified quadratic and cubic is selected according to NPOL 1 10 ASSM A EK NBAND NEL This subroutine adds the EK s to the global matrix A Part IV VFSMOD Appendices 101 1 11 BCA A NBAND Plug in first kind of BC Dirichlet in the system matrix A 1 12 FACTOR A N NBAND Perform the lower and upper decomposition LUD over the system matrix A and store the lower and upper triangular matrices on the old A matrix 1 13 GASUB TIME DT L R RAIN NEND TRAI This subroutine solves the infiltration problem for unsteady rainfall case using the Green Ampt infiltration model After ponding at the surface is detected the infiltration is allowed to reach its maximum potential for the rest of the run The assumption here is that the incoming field runoff moving at the surface will supply enough water to sustain the maxi mum infiltration for that time step This means
34. is the instantaneous infiltration rate or infiltration capacity for ponded conditions m s K is the saturated vertical hydraulic conductivity m s M 0 0 is the initial soil water deficit m m Sy is the average suction across the wetting front m F is the cumulative infiltration after ponding m F is the cumulative infiltration for the event m is the actual time s the time to ponding and f is the shift of the time scale to correct for not having ponded conditions at the start of the event ARE MT out Outflow Aout Sediment deposition T AME OY Leh Fob Figure 2 Domain discretization for the finite element overland flow submodel Rainfall excess i in equation 1 is calculated for a given rainfall distribution for each node and time step by the infiltration model The hydrograph representing runoff from the adjacent field is input as a time dependent boundary condition at the first node of the finite element grid The program allows for spatial variation of the parameters n and S over the nodes of the system Figure 2 This feature of the program ensures a good representation of the field conditions for different rainfall events The model can be operated to provide information on the effect of soil type infiltration slope surface roughness filter length storm pattern and field inflow on VFS performance i e reduction of the runoff peak volume and velocity Mufioz Carpena et al 1993b
35. level of confidence that the adopted design has against the uncertainties present when selecting the model inputs Parsons and Mufioz Carpena 2001 2002 Finally a sensitivity analysis procedure is included in the GUI to identify the parameters to which the model is more sensitive for a given scenario thus allowing the user to economize effort by focusing on better identifying just the sensitive parameters Parsons and Mufioz Carpena 2001 An example of design results see Mufioz Carpena and Parsons 2002 is included below The graph depics the optimal filter lengths to achieve a 7596 sediment reduction SDR 0 25 in a North Carolina Piedmont site clay soil 0 5 Ha source area 2 slope 6 hr storm duration with a grass mixture vegetation on the filter Filter lengths from 14 57 m are needed to accomodate storm events associated to 1 10 year return periods The design assumes homogeneous sheet flow across the filter in all cases 0 9 0 8 rc Q os 2 a fos T 10 yr 2 AQ o4 E T 2 yr 5 03 T 1 yr 75 sediment reduction line 0 2 0 1 0 20 40 60 80 100 120 Filter length m Part I VFSMOD W Model Documentation 31 6 Potential Users and Applications of the Modelling System VFSMOD is a research model as such potential users are modelers and scientists involved in studies of sediment pollution from agricultural sources and its control with the aim to gain a better understanding of the proces
36. loam 60 25 0 01914 0 0325 0 000 160 14 Loamy very fine sand 84 8 0 03726 020325 0 025 90 15 Loamy fine sand 84 8 0 02301 0 0000 0 025 120 16 Loamy sand 84 8 0 01624 0 0325 0 025 1395 17 Loamy coarse sand 84 8 0 00982 0 0325 0 025 180 18 Very fine sand 90 Ja 0 04401 0 0325 0 050 140 19 Fine sand 90 Ds 0 02173 0 0000 0 050 160 20 Sand 90 Dis 0 01481 0 0325 0 050 130 21 Coarse sand 90 55 0 00827 0 0325 0 050 200 For the selected soil type Sandy clay K 0 041 kg h N m 2 d50 66 00 um MISCELLANEOUS CALCS L 1 447 S 0 182 cfact 1 00 pfact 1 00 FINAL CALCS A 1 84779 kg m 2 Using Rm Foster A 1 05518 kg m 2 Using Rw Williams A 1 19323 kg m 2 based on Gleams Conc 29 18056 g L Using Rm Foster Conc 16 66349 g L Using Rw Williams Conc 18 84364 g L based on Gleams eoo0o ooo e e E o a e E e O e E a A A e a S ee E E e ER Part II VFSMOD and UH User s Manual These results are depicted in the next Figure 8 o q I rainfall 6 2 f e E Ea E E c tS e cc 2 6 o 8 0 2 4 6 8 10 12 Time hours Part II VFSMOD and UH User s Manual 65 Part III VESMOD W User s Manual 1 Installation Information The dsign oriented computer package consists of three programs to assist users in evaluating and developing design specifications for vegetative filter strips for trapping sediment and enhancing infiltration The programs are the graphical user interface G
37. next time step thus surface changes due to sediment deposition within the filter sediment wedge area are accounted for in the next time step of the hydrology simulation as described in the previous section 2 5 Model inputs The program reads inputs model parameters and model input variables from external ASCII files which can be prepared from given examples using a conventional text editor A summary of the model inputs is given in the following Table Class Inputs Green Ampt infiltration Rainfall hyetograph soil saturated hydraulic conductivity soil saturated water content soil initial water content soil suction at the wetting front and surface storage Overland flow Field inflow hydrograph filter length filter width nodal slopes and Man ning s roughness across the filter Sediment filtration Modified grass Manning s roughness Manning s roughness for bare soil incoming sediment characteristics median particle size weight density fall velocity effective filter media spacing and height porosity of deposited sediment incoming sediment inflow concentration sedimentograph and proportion of fine sediment General Number of nodes for the domain Courant number for numerical solution total time for the simulation Part II of this manual gives suggested literature values for some of these parameters when no field measurements are available In the case of the soil hydraulic and s
38. number of nodes of the system must be an odd number for a finite element quadratic solution an even number if the solution is cubic and any of them if linear The program adjusts the number of nodes automatically if the requirement is not made e Jf no incoming sediment characteristics are known d Zs In the absence of measured inflow sediment characteristics an estimate of the particle size could be made by knowing the soil texture of the contributing field Woolhiser et al 1990 d in x10 cm Soil texture USDA Expected d Soil texture Expected d Clay 0 45 Clay loam 5 30 Silty clay 2 45 Sandy loam 35 160 Silty clay loam 3 46 Loamy sand 90 180 Silt loam 3 50 Sandy clay 2 130 Silt 8 30 Sandy clay loam 21 160 Loam 9 60 Sand 140 200 f Setting the total simulation time DR The last time interval of the rainfall series file irn is used to set the desired simulation typically with the rainfall intensity set to 0 g Reducing execution time by stopping surface changes during the simulation ICO 0 Setting the flag ICO 0 in the igr file will stop the model from reshaping the entrance of the filter during sediment deposition This in turn will result in a reduction of the total execution required since the problem will become less non linear and fewer iterations to convergence will be needed for each time step Initial testing of the program showed that Part II VFSMOD an
39. s The sediment balance for the simulation was Total sediment inflow 116 40 g cm 45 030 Total sediment outflow 0 4195 g cm 162 3 Trapping efficiency T 99 6 VFSMOD finally predicts the final sediment wedge geometry and deposition over the filter as Sediment wedge depth Y t 0 85 cm Sediment tail at field X t 15 05 cm Sediment wedge length X t 4 55 cm Effective filter length L t 860 95 cm Part II VFSMOD and UH User s Manual 55 Sediment depth in low section DEP 0 145 cm Rough mass balance wedget depth error lt 1 1 7 2 4 Filter performance indicators file sample osp Parameter Value Units Source Area input 136 00 m2 Source Flow Length input 34 00 m Source Area Width input 4 00 m Filter Strip Length input 8 65 m Filter Strip Width input 3 87 m Mean Filter Mannings Roughness input 0 400 Ratio of Filter Length to Source Flow Length 25 46 Total Rainfall 25 15 mm Total Rainfall on Filter 0 842 m3 Total Runoff from Source mm depth over Source Area 9 74 mm Total Runoff from Source 1 324 m3 Total Runoff out from Filter mm depth over Source Filter 4 53 mm Total Runoff out from Filter 0 767 m3 Total Infiltration in Filter 1 399 m3 Runoff Delivery Ratio RDR 0 579 Mass Sediment Input to Filter 45 03 kg Concentration Sediment in Runoff from
40. s roughness coefficient s m 1 3 slope of the element duration of the simulation s Source area width m Source area flow path length m Distance from origin to the start of the i th surface segment m Part IV VFSMOD Appendices 107 TE THETAW VL VNI W 5 5 WF I X 5 5 X1 5 5 XM N XON 2 2 Infiltration AGA BGA CP CU DM F FPI L LO NCHK NPOND NEND OI OS PS PSOLD PST RAIN 50 2 RO SCHK RPEAK SAV SM STO TP TPP TI TRAI VKS Henderson s time to equilibrium s time weight factor Filter length m Mean filter Manning s roughness coefficient s m 1 3 Gauss quadrature weights modified weighting functions solution vector dimension 1xn at time step I 1 Gauss quadrature point solution vector xn at iteration m time step I 1 solution vector xnj at time step Green Ampt s A saturated hydraulic conductivity Ks m s Green Ampt s B Ks Sav M m2 s Chu s surface condition indicator for ponding at initial time Chu s surface condition indicator for no ponding at initial time initial soil water deficit M cumulative infiltration m cumulative infiltration when the end to ponding in reached m rainfall period index to show if time step is in the same rainfall period LO L Node number for flood checking flag for ponded 71 non ponded 70 surface conditions indicates that the end of runoff is reached initial soil water content saturated soil water co
41. source Area 34 00 g L Mass Sediment Output from Filter 0 16 kg Concentration Sediment in Runoff exiting the Filter 0 21 g L Mass Sediment retained in Filter 44 87 kg Sediment Delivery Ratio SDR 0 004 Effective Filter Length 8 65 m Wedge Distance 0 05 m a Used for design see Part I Section 5 on page 30 Part II VFSMOD and UH User s Manual 56 2 UH for Input Preparation User s Manual 2 1 Installing and running UH UH is installed by default when installing VFSMOD See Section 1 2 on page 40 for details When running UH from the command line DOS and UNIX versions the name of the input file set to process is selected at the command line In this way different problems can be run from the same directory without overwriting previous results As an example one could run from the VFSMOD directory uh sample2 In this example the input file sample2 inp included in the distribution package would be read from the NPUTS subdirectory After you execute the command you should see a screen as follows e e ACCAC e CeCe e March 2002 v1 06 R Munoz Carpena Urb Parsons UFL USA NE SUNCUS carpena ufl edu john_parsons ncsu edu PROGRAM GENERATE RAINFALL AND RUNOFF INPUTS FOR VFSMOD Opening inputs sample2 inp Opening output sample2 out Opening output sample2 hyt Opening inputs sample2 iro Opening inputs sample2 irn Opening inputs sample2 isd Durin
42. source code and copy the executable files vfsm and UH to the VFSMOD directory If your FORTRAN compiler name is not f77 you will need to edit the makefile found in the src directory You can also clean the executable and object files by typing setup clean d Run the sample case named sample by typing vfsm sample at the UNIX prompt Please note that the second part of the command issued sample refers to a set of files located in the subdirectory inputs You could run a different problem by selecting a different set of input files with the condition that they are located in the subdirectory inputs Note that you must have all the six input files in order to run the program In our example if you issue the s command within the inputs directory you should see the following files sample igr sample kw sample irn sample iro sample isd sample iso After you execute the command you should see a screen similar to the one given above During the run a new set of files is created in the output directory sample ogl sample og2 sample ohy sample osm sample osp The content of both input output files is explained in detail in the following section 1 3 Using the project file for input and output Versions 1 04 and later now allow the user to create project files These files contain the list of input and output files for the model This enables the user to mix and match inputs from multiple simulation scenarios Each line of the project file contains
43. the Button ta set the Parameters Base Values Distribution parameters V Green Ampt Ksat VKS cm h 4788 Set Parameters Green Ampt Theta Initial cm 3 cm 3 125 Set Parameters Particle Class Diameter cm h SetParameters Media Element Spacing 83 cm 2 2 Select Distribution v SetParameters nmi 10 Set UH Parameters z Load A Different Do Simulations Base Project Cancel Help Once the simulations are complete the user can do some analysis using VFSMOD Selected storm outputs are saved in the output file The format of this file is space separated and is easily imported into another analysis package such as spreadsheet The first thirteen lines contain header and general information on the parameter and the base project file This information includes the parameters and their probability distributions and the base rainfall and filter strip length along with the base project filenames Lines 3 10 include the information on each input parameter 0 7 indicating the parameter selection of the probability distribution for sampling the inputs the options are 1 no uncertainty 0 normal 1 lognormal 2 triangular or 3 uniform and the parameters to define the probability distribution as shown below Distribution Distribution Parameters Number 1 Not Sampled 0 Normal Mean Standard Deviation 1 Lognormal Log of Mean and Log of the Standard Deviation 2 Triangular Peak Minimum and
44. well as print out of graphical results Ranges of user selected parameters are now automatically checked against physically admissi ble values e VFSMOD and UH have been further refined to improve integration with the GUI envi ronment and graphical inputs Improved handling of special cases small runoff impermeable surfaces saturated soils etc 8 1 2005 RELEASE V3 0 XX Anumber of items were cleaned up in all of the code Further testing of the sensitivity and uncertainty routines were done A fairly extensive design procedure was added Other changes can be found in the text logs in the install directories Part III VFSMOD W User s Manual 98 Part IV VFSMOD Appendices 1 APPENDIX 1 Description of the model subroutines The source code is distributed with the model This section is intended to be used with the source code which contains more detailed documentation 1 1 Program VFSMOD The main program is the driver for the program subroutines as discussed in the previous section This is done on the following steps a print banner get I O file names and open the files b initialize matrices c read inputs for sediment problem d get inputs and parameters for hydrology problem e get the Gauss quadrature parameters f assemble the system matrix A g perform LU decomposition over A h Start the time loop to solve the problem for each time step h 1 select the rainfall intensity and BC
45. with little or no concentrated flow pathways it lumps rill and interrill erosion The R factor combines rainfall and runoff erosivity In the annual version of the equation the units are usually expressed as EI units per unit time The original units used by Wischmeier are 100 ft tons acre in h which are often referred to as the Wishmeier English EI units R ranges from 50 550 for eastern US In North Carolina R ranges 330 in the Southeastern portion of the state to 175 in the Appalachians In the Piedmont area the annual R is approximately 250 Foster 1982 indicates that no single metric unit has been accepted although for modeling convenience he suggests Newtons h So to convert the Wischmeier English units to N h multiply R by 1 702 The soil erodibility factor K is generally selected based on the top soil The english units for K are tons acre EI with typical values ranging from 0 05 0 60 The SI metric units for K are usually expressed as kg N h m The factor to convert english units to SI metric is to multiply by 0 1317 So for soil losses A RK the two quantities in the USLE with dimensions expressed as kg m then the SI units for R is N h K can be approximated based on data from Wischmeier et al 1971 He developed a regression equation based on data collected from 55 midwestern soils using percentages of organic matter primary particles sand silt clay and permeability In GLEAMS this relationship was further
46. with type of shape function selected and if not print message d read rainfall distribution from irn e read soil inputs from iso and calculate Green Ampt parameters f get downslope node for flood checking SCHK g read runoff inflow at upper side of strip BC in m s from iro h find the bandwidth for the matrix number of elements and number of nodes i calculate convergence and wave form parameters CR C FR FK j calculate the PG Parameters from the Courant number values k set the order of the integration rule 1 output parameters Part IV VFSMOD Appendices 100 1 2 output hydrological and numerical parameters l 1 output nodal information if selected ielout 1 1 2 output values for sediment transport read previously in GRASSIN m issue a warning if any of the criteria CR FR FK is not met n print heading for tables in output files 1 6 QUAD Get the Gaussian Quadrature points for orders 1 through 5 1 7 FORMA A NBAND PGPAR This subroutine assembles the system matrix A as a banded matrix This procedure involves the calculation of element matrices EK subroutine ELEM and their accumula tion in the banded system matrix A subroutine ASSM Finally we end up by plugging in the BC for the problem subroutine BCA 1 8 ELEM EK PGPAR Form the element arrays EK a first initialize the element arrays b begin integration point loop for the Gauss quadrature rule b 1 obtain shape
47. 0 18 17 13 11 30 32 2600 30 26 24 22 21 17 14 36 Part IV VFSMOD Appendices 119 Spring Cover Soil loss ratio for cropstage period and canopy cover Cover Crop Sequence Resi After No and manmagement due Plant F SB 1 2 3 80 90 96 4Lf LB Chisel shallow disk or fld cult as only tillage 33 On moderate Slopes 6000 70 8 8 7 7 17 34 60 10 9 8 8 17 35 50 13 11 10 9 18 36 40 15 13 11 10 19 37 30 18 15 13 12 20 38 20 23 20 18 16 21 39 On moderate slopes 4500 70 9 8 7 7 18 40 60 12 10 9 8 18 41 50 14 13 11 9 19 42 40 17 15 13 10 20 43 30 21 18 15 13 21 44 20 25 22 19 16 22 45 Do 3400 60 13 11 10 10 8 20 46 50 16 13 12 12 9 24 47 40 19 17 16 14 11 25 48 30 23 21 19 17 14 26 49 20 29 25 23 21 16 27 50 10 36 32 29 24 20 30 51 Do 2600 50 17 16 15 15 13 10 29 52 40 21 20 19 19 15 12 30 53 30 25 23 22 22 18 14 32 54 20 32 29 28 27 22 17 34 55 10 41 36 34 32 25 21 37 56 Do 2000 40 23 21 20 20 15 12 37 57 30 27 25 24 23 19 15 39 58 20 35 32 30 28 22 18 42 59 10 46 42 38 33 26 22 47 On slopes gt 12 lines 33 UNE D factor of z 3 13 13 ia 10 fro 10 10 Disk or harrow after spring chisel or field cultivation lines
48. 02 yields consistent SI metric units of N h In GLEAMS and the daily rainfall version of CREAMS the EI3 for a 24 hour rainfall Vp in inches is computed as El 1 51 7 87V 31 The units for the daily EI5 are ft ton acre in For daily rainfall amounts another approximation for EI for a storm is 1 51 EI 80V 32 where Vp volume of rainfall in inches The default units for EI are ft tons in h and if we multiply by 1 702 then we obtain N h Foster et al 1977 suggested an improved erosivity factor for a single storm over that of substituting storm EI for R This approach combines the effect due to runoff and rainfall into the erosivity factor So for a single storm Foster et al 1977 defines R in N h Wile Ry O5Rg 035V o5 33 Rg E Izo where E storm s total energy and I559 maximum 30 min rainfall intensity in N h V volume of runoff mm Bou peak rate of runoff mm h Williams 1975 suggested a further modification to R to handle areas larger than field scale This modification makes an attempt to account for deposition within the area which would reduce the sediment losses from the area Foster et al 1982 reported the modification of R as R 9 05 VQ 34 Part I VFSMOD W Model Documentation 24 where R storm modified R see below for explanation of units V volume of runoff m Q peak discharge rate m s Using R in place of R in the USLE is referred to
49. 12 12 11 7 4 2 t 130 3400 60 16 14 12 7 4 2 131 50 22 18 14 8 5 3 132 40 27 21 16 9 5 3 133 30 32 35 18 9 6 3 134 20 38 30 21 10 6 3 135 Do 2600 40 29 24 19 9 6 3 136 20 43 34 21 11 7 4 137 10 52 39 27 12 7 4 138 Do 2000 30 38 30 21 11 7 4 139 20 46 36 26 12 7 4 140 10 56 43 30 13 8 5 141 In disked stubble Rdr 79 62 42 17 11 6 142 Winter G after fall TP HP 31 55 48 31 12 7 5 RDL 143 GP 36 60 52 33 13 8 5 144 FP 43 64 56 36 14 9 5 145 LP 53 68 60 38 15 10 6 Grain after Summer Fallow 146 With grain residues 200 10 70 55 43 18 13 11 u 147 500 30 43 34 23 13 10 8 148 750 40 34 27 18 10 7 7 149 1000 50 26 21 15 8 7 6 150 1500 60 20 15 12 7 5 5 151 2000 70 14 11 9 T 5 5 Part IV VFSMOD Appendices 123 Spring Cover Soil loss ratio for cropstage period and canopy cover Cover Crop Sequence Resi After No and manmagement due Plant F SB 1 2 3 80 90 96 4Lf LB 152 With row crop residues 300 5 82 65 44 19 14 12 153 500 15 62 49 35 17 13 11 154 750 23 50 40 29 14 11 9 155 1000 30 40 31 24 13 10 8 156 1500 45 31 24 18 10 8 7 157 2000 55 23 19 14 8 7 5 158 2500 65 17 14 12 7 5 4 POTATOES 159 Rows with slope 43 64 56 36 26 19 16 Contoured rows ridged when canopy cover is about 160 10 43 64 28 18 13 10 8 a Symbols B soybeans C co
50. 13 Rawls W J and D L Brakensiek 1983 A procedure to predict Green Apmt infiltration parameters Adv in Infiltration pp 102 112 ASAE Pub no 11 83 U S NRCS Formerly Soil Conservation Service National Engineering Handbook Hydrology Section 4 1972 and USDA ARS 41 172 1970 USDA NRCS 210 VI TR 55 2nd Edition June 1986 Wischmeirer W H and D D Smith 1978 Predicting rainfall erosion losses a guide to conservation planning Agriculture Handbook No 537 USDA Washington DC 58 pp Part IV VFSMOD Appendices 125
51. 18 Agriculture Handbook 537 The three columns for cropstage 3 are for 80 90 and 96 to 100 percent canopy cover at maturity f Column 4L is for all residues left on field Corn stalks partially standing as left by some mechn anical pickers If stalks are shredded and spread by picker select ratio from Table When residues are reduced by grazing take ratio from lower spring residue line g Period 4 values in lines 9 12 are for corn stubble stover removed h Inversion plowed no secondary tillage For this practice residues must be left and incorporated i Soil surface and chopped residues for matured preceding crop undisturbed except in narrow slots in which seeds are planted j Top of old row ridge sliced off throwing residues and some soil into furrow areas Reridging assumed to occur near end of cropstage 1 k Where lower soil loss ratios are listed for rows on the contour this reduction is in addition to the standard field contouring credit The P value for contouring is used with these reduced loss ratios l Field average percent cover probably about three fourths of percent cover on undisturbed strips m If again seeded to WC crop in corn stubble evaluate winter period as a winter grain seeding lines 132 148 Otherwise see table E 9 n Select the appropriate line for the crop tillage and productivity level and multiply the listed soil loss ratios by sod residual factors from table E 10 o Spring residue may include ca
52. 3 82 2192 298 4 920 26558 78 12 10 23583 94 10 76 888 4 999 i TR Insert i The format of this file is space separated that is easily imported into another analysis package such as spreadsheet To import in a spreadsheet one selects space separated data treat multiple spaces as one The first five lines denote general information on the Part III VFSMOD W User s Manual 87 parameter and the base project file This information includes the parameter range total rainfall for the event and the filter strip length along with the base project filenames The tabular information presents the event level outputs and starts on the 7 line Each line contains the results for one of the simulations The columns are retv the return value for that simulation 0 indicates that simulation had no errors CN the curve number input UHk soil erodibility K input UHc crop factor input UHp practice factor input isoks the Green Ampt saturated K input aRoa isothetai Green Ampt initial soil water content and igrss stem spacing input Next the summary outputs for the storm are given These include FldROmm and FldROm3 the runoff from the source area field in mm and m3 VFSROmm and VFSROm3 the runoff from the vegetative filter strip area in mm and m3 VFSinfm3 the amount of infiltration in the vegetative filter strip in m3 FIdSEDkg and FldSEDconc the sediment from the source area field in kg and kg L VFS
53. 300 1 5 13 0 012 VEGETATION NOT RECOMMENDED FOR VFS Alfalfa 1075 3 02 35 0 0084 Sericea lespedeza 650 3 92 40 0 0084 Common lespedeza 325 5 52 13 0 0084 Sudangrass 110 9 52 0 0084 a To convert densities for good stand to other stands multiply the given densities by 1 3 2 3 1 4 3 and 5 3 for poor fair good very good and excellent covers b Values vary depending on mixture If a given grass type predominates values for that species should be used c Values of Ss above 2 5 cm can cause scour and are not recommended Part IV VFSMOD Appendices 112 3 4 NRCS SCS Curve Numbers Runoff curve numbers for urban areas From USDA NRCS 210 VI TR 55 2nd Edition June 1986 Table 2 2a Cover Description Curve Numbers for hydrologic soil group Average d hydrologic conditi pergen A B D Cover type and hydrologic condition impervious C area Fully developed urban areas vegetation established Open space lawns parks golf courses cemeteries etc P Poor condition grass cover lt 50 68 79 86 89 Fair condition grass cover 50 to 75 49 69 79 84 Good condition grass cover gt 75 39 61 74 80 Impervious areas Paved parking lots roofs driveways etc 98 98 98 98 excluding right of way Streets and roads Paved curbs and storm sewers exclud 98 98 98 98 ing right of way Paved open ditches including 83 89 92 93 right of way Gravel including r
54. 45 2 2 40 86 2042 930 40 82 2041 882 3 125 24513 18 12 00 22476 14 11 01 917 999 O 74 111075 48 7 6 4 88661212960083 1 210802263416314 2 2 25 89 1294 651 25 82 1291 478 5 250 13457 08 10 39 12600 89 9 76 936 998 O 64 77499 49 7 6 2 35464934840968 1 11534063532749 2 2 43 46 2172 964 43 43 2172 407 2 635 26289 38 12 10 23736 87 10 93 903 1 O 69 81858 48 7 6 5 91717141296498 1 106626425478746 2 2 20 22 1011 121 20 13 1007 201 5 997 9502 44 9 40 8681 57 8 62 914 996 lee 73 05277 48 7 6 4 07537396565465 1 276156811532463 2 2 24 41 1220 653 24 37 1218 975 3 754 12325 13 10 10 11478 27 9 42 931 999 oft 4 ali insert EditPad Lite 4 5 0 Copyright 1996 2002 Jan Goyvaerts http www EditPad ite com E In addition the Analysis option for the Uncertainty section includes some analysis options for the data These options include plots of the frequency distribution and cumulative probability distributions These can be done for each sampled input parameter and for any of the output parameters V Working with E vfsmod w combo 2 testguloutputlUncResults Sy TOmdxt ii 0 x Change UncResuts File C UH SoilErodibaly Source Funott m 3 f Filter Sediment kg DHC Fottor Filter Runo mm Riese cus RUHE DFA Filter Sediment Concentration g L Filter Puno m 3 Select Input Parameter Select Output Parameter Source Sediment ka Source Runoff mm S
55. 4E 04 1800E 04 5080E 05 2100E 04 1693E 05 2400E 04 2540E 05 2700E 04 8467E 06 3001E 04 0000E 00 3603E 04 0000E 00 Note the last pair of numbers is used to set the time when the simulation ends 1 4 3 filename iro runoff from the adjacent field into the VFS 1 4 3 1 Structure of the file SWIDTH SLENGTH NBCROFFBCROPEAK BCROFF 1 J J 1 2 Part II VFSMOD and UH User s Manual 46 1 4 3 2 Definition SWIDTH Source area width m SLENGTH Source area flow path length m NBCROFF integer number of time steps of the incoming field hydrograph BCROPEAK peak flow of the incoming field hydrograph m s BCROFF I J incoming field hydrograph flow rate time s vs qin m3 s 1 4 3 3 File example 4 0 34 0 68 2192E 02 8417E 03 0000E 00 8716E 03 5724E 07 9018E 03 5724E 07 9317E 03 5724E 07 1 4 4 filename iso soil properties for the infiltration model 1 4 4 1 Structure of the file VKS SAV OS OI SM SCHK 1 4 4 2 Definition VKS saturated hydraulic conductivity K m s SAV Green Ampt s average suction at wet front m OS saturated soil water content 0 m m OI initial soil water content 0 m m SM maximum surface storage m SCHK relative distance from de upper filter edge where the check for ponding conditions is made i e 1 end filter 0 5 mid point 0 beginning 1 4 4 3 File example 1 33e 5 0 37904 0 311 0 125 0 0 1 00 Part II
56. 77 0 49735 0 11985 0 4 2 30726 0 46541 0 11094 0 45 2 24876 0 41314 0 11508 0 50 2 17772 0 36803 0 09525 To obtain the coefficients rather than interpolating in the previos Table a set of fourth order polynomials were obtained see next Table Part I VFSMOD W Model Documentation Storm Coef A B C D E Co 68 0317 74 693 249255 3 9797 2 5222 l C 82 907 105222 42 167 6 7479 0 8657 5 11 1619 26 314 16 1126 2 9776 0 0456 Co 144 547 136 68 41 8526 6 2829 2 3645 IA C 130 64 134 907 45 773 6 585 0 6384 C 55 230 47 9565 13 503 2 1954 0 2644 Co 11 312 12 1681 6 5688 1 0577 2 5021 i C 16 6125 16 337 64981 1 1784 0 5476 05 43 015 50 4334 19 740 3 2996 0 3427 Co 11 505 14 2182 7 8919 1 3836 2 4007 m C 64 177 85 7116 38 206 6 7419 0 8899 C3 65 9007 85 806 39 0036 6 8946 0 2078 a CEAQSP HBU PV COPY DU P E i 0 1 2 Part I VFSMOD W Model Documentation N 9 5 Storm type c o CO o n C1 ES C2 3 c gt t 9 9 9 n Sor 2 x goede Ave Kc AM A D 7 i 4 wee a lt Sess aj m E 0 1 0 2 0 3 0 4 05 IP Storm type IA T O o C0 x D C O 2 C 9 o o T gt 9 9 oO JOE EA mt aen 2278 Ak decumexe n jasar paa 0 1 0 2 0 3 0 4 05 I P Coefficient C0 C1 C2 Coefficients C0
57. 85 Contoured amp terraced Poor 66 74 80 82 C amp T Good 62 71 78 81 C amp T CR Poor 65 713 79 81 Good 61 70 77 80 SR Poor 65 76 84 88 Good 63 75 83 87 SR CR Poor 64 75 83 86 Good 60 72 80 84 C Poor 63 74 82 85 Solent Good 61 73 81 84 C CR Poor 62 73 81 84 Good 60 72 80 83 Poor 61 72 79 82 Good 59 70 78 81 C amp T CR Poor 60 71 78 81 Good 58 69 77 80 SR Poor 66 77 85 89 Close seeded or site ii i in i broadcast C Poor 64 75 83 85 legumes or rota Good 55 69 78 83 tion meadow C amp T Poor 63 73 80 83 Good 51 67 76 80 1 Average runoff condition Ia 0 2S Part IV VFSMOD Appendices 115 a Crop residue cover applies only if residue is on at least 5 of the surface throughout the year b Hydraulic condition is based on combination factors that affect Infiltration and runoff including a density and canopy of vegetative areas b amount of year round cover c amount of grass or close seeded legumes d percent of residue cover on the land surface good gt 20 and e degree of surface roughness Poor Factors impair infiltration and tend to increase runoff Good Factors encourage average and better than average infiltration and tend to decrease runoff Part IV VFSMOD Appendices 116 Runoff curve numbers for other agricultural lands Table 2 2c From USDA NRCS 210 VI TR 55 2nd Edition June 1986 Cover Description Curve numbers for hyd
58. C Hayes 1994 Design Hydrology and Sedimentology for Small Catchments San Diego Academic Press Haan C T B Allred D E Storm G J Sabbagh and S Prabhu 1995 Statistical Proce dure for Evaluating Hydrologic Water Quality Models TRANS ASAE 38 3 725 733 Haan C T D E Storm T Al Issa S Prabhu G J Sabbagh and D R Edwards 1998 Effect of Parameter Distributions on Uncertainty Analysis of Hydrologic Models TRANS ASAE 41 1 65 70 Part I VFSMOD W Model Documentation 36 Hayes J C 1979 Evaluation of design procedures for vegetal filtration of sediment from flowing water unpublished Ph D dissertation Univ of Kentucky Lexington KY USA Hayes J C B J Barfield and R I Barnhisel 1979 Filtration of sediment by simulated vegetation II Unsteady flow with non homogeneous sediment Transactions of ASAE 22 5 1063 1967 Hayes J C B J Barfield and R I Barnhisel 1982 The use of grass filters for sediment control in strip mine drainage III Empirical verification of procedures using real veg etation Report No IMMR82 070 Int for Mining and Mineral Res Univ of Ken tucky Lexington KY Hayes J C B J Barfield and R I Barnhisel 1984 Performance of grass filters under laboratory and field conditions Transactions of ASAE 27 5 1321 1331 Kizil U and L A Disrud 2002 Vegetative Filter Strips Modeling of a Small Watershed 2002 ASAE Annual International Meeting CIGR Annua
59. C Foster CREAMS GLEAMS Close this Window Help The inputs for the UH program are entered in the text boxes Rainfall This is the total rainfall for the storm in mm Curve Number This is the NRCS curve number for the source area The range is from 0 to 100 There are tables in the appendices to select See NRCS SCS Curve Numbers on page 113 for Agricultural and Urban source areas The curve numbers given in these tables represent Antecedent Moisture Condition AMC II which is average moisture conditions Part III VFSMOD W User s Manual 72 Length This is the length of the source area in m or the distance from the edge of the area bordering the filter strip along the upslope line to the farthest upslope point contributing runoff to the filter strip Area This is the source area in hectares Slope This is the slope of the source area as a fraction or the slope divided by 100 Storm Duration The time of the storm in hours used to compute the hyetograph and hydrograph Storm Type This is the type of rainfall event 1 IA II or III Type I is typically associated with Hawaii coastal side of Sierra Nevada in southern California and the interior regions of Alaska Type IA is used to represent storms for the coastal side of the Sierra Nevada and the Cascade Mountains of Oregon Washington and northern California and the coastal regions of Alaska Type II is used to represent most of the remaining area
60. E Parsons and J W Gilliam 1993b Numerical approach to the overland flow process in vegetative filter strips Transactions of ASAE 36 3 761 770 Mufioz Carpena R J E Parsons and J W Gilliam 1999 Modeling hydrology and sedi ment transport in vegetative filter strips and riparian areas J of Hydrology 214 1 4 111 129 Mufioz Carpena R and J E Parsons 1999 Evaluation of VFSmod a vegetative filter strips hydrology and sediment Paper of ASAE no 992152 ASAE St Joseph Mufioz Carpena R and J E Parsons 2002 A normalized design procedure to meet sedi ment TMDL with vegetable filter strips In Watershed Management to Meet Emerg Part I VFSMOD W Model Documentation 37 ing TMDL Environmental Regulations Proc 11 13 March Fort Worth Texas USA eds A Saleh B Wilson pp 256 261 St Joseph Michigan ASAE Parsons J E R B Daniels J W Gilliam and T A Dillaha 1991 The effect of vegeta tion filter strips on sediment and nutrient removal from agricultural runoff In Proc of the Environmentally Sound Agriculture Conference ed A B Bottcher K L Campbell and W D Graham 324 332 Orlando FL April 16 18 1991 Parsons J E and R Munoz Carpena 2001 Impact of Uncertainty on the Design of Veg etative Filter Strips Statistical Methods in Hydrology for the 2001 ASAE Annual International Meeting Sacramento California ASAE Paper of ASAE no OI ASAE St Joseph Parsons J E and R Muf
61. ETATIVE FILTER STRIP OF AN INFLOW HYDROGRAPH FROM AN ADJACENT FIELD DURING A STORM EVENT VFSMOD HANDLES THE CASE OF VARYING SURFACE COVER AND SLOPES AT THE NODES AND TIME DEPENDENT INFILTRATION FOR THE DOMAIN Reading inputs from inputs sample igr Reading inputs from inputs sample isd Reading inputs from inputs sample ikw Reading inputs from inputs sample irn Reading inputs from inputs sample iso Reading inputs from inputs sample iro LE Sitcom Ome Unis Cis wiles Sil RUNNING FINISHED VFSMOD v1 06 03 2002 During the run a set of new files is created in the OUTPUT directory SAMPLE OGI SAMPLE OG2 SAMPLE OHY SAMPLE OSM SAMPLE OSP The content of both input output files is explained in detail in the following section 1 2 2 Installing together with the Windows Graphical Interface Windows 9x NT 2000 XP See Part III of this document describing the MS Windows version of the system 1 2 3 Installing on a UNIX system a Create a directory named VFSMOD mkdir VFSMOD mv vfsmodux tar gz VFSMOD cd VFSMOD b Expand the contents of the file vfsmodux tar gz on the new directory Part II VFSMOD and UH User s Manual 41 gzcat vfsmodux tar gz tar xvf This should create the following directory structure vfsmod docs inputs output src uh src vfsm c An installation script setup is included in the VFSMOD directory To compile and install the program simply type setup The script will compile the
62. FSMOD Built In VFSMOD W Haan et al 1995 outlined the statistical procedure for evaluating hydrology and water quality models Their procedure included conducting sensitivity analysis generating probability distributions for model inputs generating probability distributions for the model outputs and using the probability distributions of the model outputs to assess uncertainty Using an example model they conducted a sensitivity analysis to identify the input parameters that have the most impact on the outputs The absolute sensitivity S of a given output O relative to input parameter P is defined as 00 S 35 i7 3p 35 L The relative sensitivity S of the output parameter with respect to changes in the input parameter is computed as _ 20 ri 0P O 36 Once the most sensitive inputs are identified the model users can concentrate on determining the best or most appropriate values for a given desing scenario In addition these parameters can also be used to evaluate the uncertainty in the model outputs based on these most sensitive inputs This approach involves selecting probability distributions for each sensitive input based on based on previous literature and field research After the probability distributions are identified for each of the inputs then these distributions are sampled for typical inputs and the simulated outputs are used to determine a probability distribution for each output parame
63. File On the main window the Options Menu allows the user to review the program s options and user information This information is entered the first time vfsmod w is executed and can be checked and changed using the Options Menu V vfsmod w Initialization Information Emak Set Up vismod w Configuration Fila Accept and Seve ose User Name Pauser User Affliation Mises SCS User Address fiquser myemailaddress User e mail Address Directory For Saving Dwsmdw Browse Project Files Check here to turn on Debug Option usually not checked only on for this run Associate Projectfiles prj and lie with vismod w option notyet available Ta Register Emal the wamadty og File te johr_earsansi ncsu edu Thank You Fill in the registration information Be sure to select the directory where you installed vfsmod w exe for the Directory for Saving Project Files On the Options screen we have included an option to associate files with extensions prj and lis with vfsmod w exe This is currently not implemented Once available this option will allow the user to click on a file with prj or lis extensions from the Explorer window and automatically load the project You can manually accomplish this by associating these extensions with vfsmod w exe using the file Properties menu from Explorer Currently we do not have an automatic registration for vfsmod package The registration info
64. IDTH SLENGTH SX I system matrix square of dimensions nxn ie A right hand side vector of dimensions Ixn ie b time interpolated water depth at the first node of the system m boundary condition at the upstream node time s vs depth m inflow hydrograph m3 s read from input file ROFFKW IN celerity of the wave m s derivative of the i th shape basis function at XI duration of the simulation s increment of time s Courant time step for the numerical solution space step m duration of the rain s distance between nodes in element entry in element stiffness matrix convergence criteria set to 10 8 in the program kinematic flow number Froude number width of the strip m maximum flow depth at steady state condition maximum number of iterations alowed convergence flag 0 no convergence 1 convergence actual number of nodes in the domain bandwidth for the A matrix number of time steps actual number of elements in the domain order of the integration rule over each element maximum number of equations and variables that can be solved number of nodal points over each element polynomial degree 1 Petrov Galerkin parameters 171 4 i th shape function at XI nodal a in Manning s uniform flow equation flow vector at iteration m cm2 s flow vector at previous time step cm2 s maximum flow rate at steady state condition cm2 s rainfall excess at the node lateral inflow m s Manning
65. LENGTH m 11038 8 181251 mnn 112714 247196 SRSUUNIORDEGTURS 03753166400 0 375316E 00 11504 303164 aa en 11736 6 343996 119592 367828 x Insert Row above Delete Current Plot Hydrograph Current Raw Row Save Continue Editing Save and Close Close Help SWIDTH Source area width m SLENGTH Source area flow path length m NBCROFF integer number of time steps of the incoming field hydrograph BCROPEAK Peak flow of the incoming field hydrograph m3 s BCROFF I J incoming field hydrograph flow rate time s vs qin m s The hydrograph can be viewed using the Plot Hydrograph button 0 0557328 ia 0 0445863 0 0334397 0 0222931 Runoll m a s 0 0111466 0 f 112 046 440 33 768 614 10969 1425 18 1753 47 Copy Plotto Clipboard Print Plot Edit Plot Part III VFSMOD W User s Manual 81 6 Processing and Analysis of VFSMOD Results A description of the VFSMOD output files can be found in Part II of this Documentation In this version limited analysis of the output files is available These options are available from the VFSMOD menu s Outputs option Graph Results vent Balances Currently the output files can be viewed by selecting the VFS Output Viewer menu and the user can create plots of the Hydrology and Sediment Balances for the simulation The user selects a results file for each of these options o x UF Siod Oufput Viewer Pamese File output sample osp
66. Lj controls sediment trapping up to an effective maximum length value thereafter additional length does not improve filter performance This maximum effective length depends on the source area topography and the hydraulic characteristics of the strip Several modeling efforts have been undertaken to simulate VFS efficiency in removing pollutants from surface waters Researchers at the University of Kentucky Barfield et al 1978 1979 Hayes 1979 Hayes et al 1982 1984 Tollner et al 1976 1977 developed and tested a model GRASSF for filtration of suspended solids by artificial grass media The model is based on the hydraulics of flow and transport and deposition profiles of sediment in laboratory conditions This physically based model takes into account a number of important field parameters that affect sediment transport and deposition through the filter sediment type and concentration vegetation type slope and length of the filter Flow is described by the continuity equation and steady state infiltration i e flow decreases linearly from upstream to downstream in the filter Wilson et al 1981 modified and incorporated GRASSF into SEDIMOT II a hydrology and sedimentology watershed model A simple algorithm to calculate the outflow hydrograph was incorporated into the model and up to three different slope changes throughout the filter could be considered The model does not handle time Part I VFSMOD W Model Documentation 1
67. NN eec an at Socal ace e a ential 95 11 Troubleshooting VISmOGO W iu esee treten ntanstatnvtaateerecentendestavarsdastabaedeasdeteadeeeaies 97 12 WVBSMOD W Change History teret Sr eoe reete eee epa Ce Feb Ua es ditus 98 Part IV VBSMIOD Appendices issn adio hae oa art e qu on dr axo R Mar RU ER drea 99 l APPENDIX 1 Description of the model subroutines sss 99 1 1 Program die 99 1 2 EINPUT DEISEDID sete iter re OR ut e EE te 100 1 3 INI A B X XM X0 Q0 QM SSE NODENX sssssseeeseeeer ener ener 100 1 4 GRASSIN ICOARSE COARSE LISFIL eese 100 1 5 INPUTS N NBAND NRAIN RAIN NBCROFF BCROFF TE QMAX VL FWIDTH PGPAR VKS NCHK LISFIL 100 1 6 QUAD deese eintreten RR ERR SERRE ESSERE OX NR IERI EEE sb E CER Ege 101 1 7 FORMA A NBAND PGPAR eee DRE EYE EE XR EIU Eee EUH EEG US 101 1 8 ELEEM EBEK PGPAB tre ORO SHIRE E ue R Aene 101 1 9 SHAPE XIS PSI DPSI WE PGPAR seseeeeeeeeeer nennen enne nennen enne 101 1 10 ASSM A EK NBAND NEL eese eene enne enne nennen nennen ener 101 1 11 BCA A NBAND iesceistoseh seeded n Re e n Eae Oe e REUS 102 1 12 FACTOR A N NBA N D oa caedere etat de Rae wie aA 102 1 13 GASUB TIME DT L R RAIN NEND TRAD ce ceececccesseesceseeesececeaecaeeeeenseenseneeneeeseenes 102 1 14 FORMB B0 X0 Q0 N BCRO PGPAR rcce nin n E 102 1 15 MODIFY QM B BCRO PGPAR sess enne eren 103 1 16 SOLVE A B X N NBAND iei
68. SEDkg and VFSSEDconc the sediment lost from the vegetative filter strip in kg and kg L and SDR the sediment delivery ratio Mass Sediment from VFS Mass Sediment from Field and RDR the runoff delivery ratio Runoff from VFS Runoff from Field A separate file is written for each parameter The user selects the Analysis option from the Sensitivity menu and selects the file to analyze ini xl st working with E vefsmod w combo2testguioutputuhioNseris jepisen Plot Selected Output Sensitivity Analysis for Curve Number Plot Selected Output Select Output Parameter Absolute Sensitivity Il C Source Sediment kg Plat Selected Output C Source Runoff m 3 7 Source Sediment Concentration g L Relative Base Sensitivity C Fi s E Fir runai ao Filter Sediment kd C Filter Sediment Concentration g L Plot Selected Output Filter Runoff m 3 Relative Sensitivity Ree Eg EPI C Filter Infiltration m 3 C Sediment Delivery Ratio Filter Source C s x rn Dumut Sensis asus Runoff Delivery Ratio Filter Source Current Results File as Change Sensitivity E wismod w combo2 testqui output uhCNsens jep sen Dismiss File From this screen selected storm outputs are available for analyses Various plots of the outputs versus the inputs along with some statistics are available For example the Curve Number was varied from 76 to 95 and produced Source Runoff from 85 mm to 138 mm Selecting Plot S
69. UFSMOD v1 View Summary File Files for this simulation File 1 code ikw inputs sampleO ikw File 2 code irn inputs sample irn General Outputs asm File 3 code iro inputs sample2 iro File 4 code iso inputs sample iso File 5 code osm output sample osm Close File 6 code ohy output sample ohy File 7 code igr inputs sample igr File 8 code ogl output sample og File 9 code og2 output sample og2 File 10 code osp output sample osp File 11 code isd inputs sample isd Summary of Buffer Performance Indicators 50000 00 m 2 100 00 m Source firea input Source Flow Length input Part III VFSMOD W User s Manual 82 ummary File sample1 20 0sp Filter Length 8 65 m Mannings Roughness 4 Amounl m 35 Runoff In Rainfall Infiltration Component Runoff Out Copy to Clipboard Print Plot Edit Plot S1 Summary File sample1 20 08p Filter Length 8 65 m Mannings Roughness 4 Sediment Delivery Ratio 0 a 1 0 0 5 Amount kg 0 0 Sediment In Sediment Retained Component Sediment Out Copy to Clipboard Print Plot Edit Plot All of the output files are in ASCII format and can be imported into other applications for further processing We are planning to implement other analysis options in future versions Part III VFSMOD W User s Manual 83 7 Using the Plot Windows The use
70. UI vfsmod w exe version 3 00 xx or later a program to estimate rainfall hyetographs runoff hydrographs and storm based erosion losses from typical source areas UH UH exe version 1 06 or later and the vegetative filter strip model VFSMOD vfsm exe version 1 06 or later The GUI was developed to assist users in executing the Vegetative Filter Strip Model VFSMOD and UH Development of the graphical user interface program GUI was started in March 2000 Since that time we have continued to improve the interface and add new features to the system As such we expect there will be a number of bugs that may appear The graphical front end GUI for VFSMOD was developed using Visual Basic Professional Edition version 6 0 vb6 The Visual Basic source code is available upon request The programs UH and VFSMOD were developed in FORTRAN and the source code is supplied with the installation package This program is supplied to be installed using the Visual Studio Installer As such a number of controls dll s and other files are included and usually installed We have made no attempt to eliminate or reduce the package although this is a future desire If you attempt to bypass setup we have no idea what must be installed The install package includes the complete Win32 distribution for vfsmod The default installation directory is C vfsmod which can be changed to any location For example if the installation was done for D vfsmod then th
71. VFSMOD W Vegetative Filter Strips Hydrology and Sediment Transport Modelling System MODEL DOCUMENTATION amp USER S MANUAL version 2 x draft 3 x Rafael Mufioz Carpena Ag amp Bio Engineering IFAS TREC UF Homestead FL 33031 USA carpena ufl edu t2 UNIVERSITY OF Or ORID Agricultural Sciences Last Updated John E Parsons Bio amp Ag Engineering Box 7625 NCSU Raleigh NC 27695 7625 USA john parsons ncsu edu sd a4 July 30 2005 Disclaimer VFSMOD W 2 x Vegetative Filter Strip Modelling System VFSMOD was initially developed in the Department of Biological and Agricultural Engineering by Dr Rafael Mufioz Carpena under the direction of Dr John E Parsons The model and associated documentation is supplied as is with no warranty explicit or implied The model is provided to as an educational and research tool This version is the fourth moving the model from a research tool to one available for general users As with any model the results are totally dependent on the user s ability to wisely select input parameters that represent the field and to interpret the results We will make every effort to provide assistance and encouragement as our other commitments allow We do ask that you reference our work if you find it helpful in your pursuits Ag amp Bio Eng IFAS U of Florida by R Mufioz Carpena carpena ufl edu Bio amp Ag Engineering NC State University by J E Parsons john
72. ameters baselow basehigh baseinc Filter Length Media Spacing al 5 20 5 2 2 2 2 0 StemDuration 6 Amounts 20 40 60 80 100 Base Info Rainfall mm and Buffer Length m gt base uh scli lis base vfs scl i1y 5 prj 54 5 retv Rainfall InPNum InpValue FldROme FldROm3 VFSROnm VFSRON3 VFSINFm3 FldSEDkg FldSEDconc VFSSEDkg VFSSEDconc SDR RDR 0 20 0 S 2 20 10 985 0 00 0 000 11 372 163 93 14 92 REM ree MA G B 20 B io 2 20 10 985 0 00 0 000 11 759 164 58 14 98 0 00 20353 06 0 0 O 20 Bj 15 2 20 10 985 0 00 0 000 12 146 162 19 14 76 0 00 19114 77 0 0 0 20 0 20 2 20 10 984 0 00 0 000 12 532 160 21 14 58 0 00 15468 86 0 O O 40 0 S 12 80 63 976 10 93 54 867 9 883 1121 40 17 83 340 97 6 21 304 858 O 40 0 10 12 80 63 994 9 49 47 600 17 742 1120 40 3281 177 51 3 71 188 747 O 40 0 15 12 80 63 979 8 23 41 609 24 697 1121 96 17 83 96 67 2 92 086 65 O 40 0 20 12 80 63 980 7 09 36 003 31 072 1121 36 37 59 56 82 1 87 05 56 0 60 0 S 27 38 136 0985 25 97 127 333 10 723 2875 86 21 01 931 78 7 392 6324 9 O 60 0 10 27 38 136 900 23 73 119 571 19 681 2877 44 21 02 668 67 Bis sikh EU O 60 0 15 27 38 136 891 22 26 112 579 27 796 2877 37 21 02 480 30 4 27 180 B22 O 60 0 20 27 38 136 899 20 91 106 175 35 368 2877
73. an 1981 Applied Hydrology and Sedimentology for Disturbed Areas Oklahoma Technical Press Stillwater Chu S T 1978 Infiltration during unsteady rain Water Resour Res 14 3 461 466 Cooley K R 1980 Erosivity R for individual design storms In CREAMS A Field Scale Model for Chemicals Runoff and Erosion from Agricultural Management Sys tems Vol III Chapter 2 USDA SEA Conservation Report No 26 pp 386 397 Dillaha T A J H Sherrard and D Lee 1986 Long Term Effectiveness and Mainte nance of Vegetative Filter Strips VPI VWRRC Bull 153 Virginia Polytechnic Insti tute and State University Blacksburg Dillaha T A R B Reneau S Mostaghimi and D Lee 1989 Vegetative filter strips for agricultural nonpoint source pollution control Transactions of ASAE 32 2 491 496 Engman E T 1986 Roughness coefficients for routing surface runoff J Irrigation and Drainage Eng ASCE 112 1 39 53 Foster G R and L F Huggins 1977 Deposition of sediment by overland flow on con cave slopes In Soil Erosion Prediction and Control Special Publication No 21 Soil Conservation Society of America Ankeny IA pp 167 182 Foster G R 1982 Chapter 8 Modeling the erosion process In Hydrologic Modeling of Small Watersheds Editors C T Haan H P Johnson and D L Brakensiek ASAE Monograph No 5 American Society of Agricultural Engineers St Joseph MI pp 297 380 Haan C T B J Barfield and J
74. and Ia 0 28 Part IV VFSMOD Appendices 117 Runoff curve numbers for arid and semiarid rangelands Table 2 2d From USDA NRCS 210 VI TR 55 2nd Edition June 1986 Cover Description Curve numbers for hydrologic soil group C Hydrologic b B C D over type BR Condition B Herbaceous mixture of grass POG 80 87 93 weeds and low growing brush with Fair 71 81 89 brush the minor element Good 62 74 85 Poor 66 74 79 aspen mountain mahogany bitter brush maple and other brush Fer 48 i iis Good 30 4l 48 Poor 75 85 89 Pinyon juniper pinyon juniper or Fair 58 73 80 both grass understory Good 41 61 71 Poor 67 80 85 Sagebrush with grass understory Fair 51 63 70 Good 35 47 55 Desert shrub major plants include Poor 63 77 85 88 saltbush greasewood creosote j F 55 2 81 86 bush blackbrush bursage palo ae 1 verde mesquite and cactus Good 49 68 79 84 a Poor lt 30 ground cover litter grass and brush overstory Fair 30 to 70 ground cover Good gt 70 ground cover b Curve numbers for group A have been developed only for desert shrub 1 Average runoff condition and Ia 0 2S For range in humid regions use Table 2 2c Part IV VFSMOD Appendices 118 3 5 MUSLE Crop factor C Soil loss ratios CFACT to describe the effects of cropping management From 1992 GLEAMS User Manual Knisel et al 1992
75. ch segment s m 1 3 slope at each segment unit fraction i e no units V Slope and Roughness Factors I ZE x Segment Properties Change Number of Segments slope and roughness of each segment Number of Segments with different surface properties slope roughness NPROP h4 Distance m Manningsn Slope Vi 6182 4 052778 IN Segments 1 2364 4 032639 1 8546 4 071528 2 4729 4 075 3 0911 4 031944 mane 4 4 3275 4 029885 v 4 9457 4 028947 L x Cenosl Insert Row Delete Current Above Current Row 3 7083 019444 Selecting the View Segments button displays a graph of the elevation change across the filter strip The elevation change is relative to the upslope edge of the filter strip If the user changes VL the length of the filter strip then a check is made of the segment properties to ensure that the last point in SX is equal to the new buffer strip length If it is not then the View Edit Segment Properties screen is opened and a warning message box is shown reminding the user to fix the segment properties data Part III VFSMOD W User s Manual 76 V Segment Property Plot ij ia x Elevalion mj e o Er m n e B e o D Distance m Copy Plotto Clipboard Print Plot 5 2 VES Infiltration Soil Properties iso VKS SAV OS OI SM SCHK V vfsm Editing D vfsmod w inputs sample iso m x I
76. current modules available are Figure 1 RAINFALL FIELD INFLOW Kinematic Overland Flow Green Ampt Infiltration Sediment filtration VFS OUTFLOW Figure 1 Schematic representation of the VFSMOD i Green Ampt infiltration module a module for calculating the water balance in the soil surface ii kinematic wave overland flow module a 1 D module for calculating flow depth and rates on the infiltrating soil surface iii sediment filtration module a module for simulating transport and deposition of the incoming sediment along the VFS VFSMOD is essentially a 1 D model for the description of water transport and sediment deposition along the VFS The model can also be used to describe transport at the field scale or field edge if flow and transport is mainly in the form of sheet flow Hortonian and the 1 D path represents average conditions field effective values across the VFS The VFSMOD model uses a variable time step chosen to limit mass balance errors Part I VFSMOD W Model Documentation 3 induced by solving the overland water flow equation The time step for the simulation is selected by the kinematic wave model to satisfy convergence and computational criteria of the finite element method based on model inputs Mufioz Carpena et al 1993a b The model inputs are specified on a storm basis State variables are integrated after each event to yield storm outputs 2 1 Hydrology This program
77. d UH User s Manual 51 the sediment predictions do not change greatly but the user is advised to assess this point for each particular application 1 7 Sample application A sample application case is shown by using input data collected at a NC State University experimental site Raleigh NC USA The input and output files can be found in the sample case included in the distribution package obtained from the internet sites 1 7 1 Inputs 1 7 1 1 Hydrological inputs files sample ikw and sample iso Description symbol INPUT Value Units Source area flow path length Ls SLENGTH 34 0 m Source area width w SWIDTH 4 0 m Filter length L VL 8 655 m Filter width w FWIDTH 3 87 m Filter mean Manning s coefficient calculated n VN 0 40 sm Duration of the simulation DR 3603 S Number of nodes N 57 Number of different filter segments NPROP 14 Courant number Cr CR 0 8 Order of shape functions NPOL 3 quadratic Petrov Galerkin flag KPG 1 Number of different filter segments NPROP 14 Saturated hydraulic conductivity K VKS 1 33 x105 m s Average suction at the wet front Say SAV 0 379 m Water content at saturation 0 OS 0 311 Initial water content 0 OI 0 125 Surface storage Sm SM 0 0 m The flow inputs rainfall and incoming runoff from the field are shown later in the 1 7 1 2 Sediment transport files sample igr and sample isd output
78. d in overland flow routing can be taken from Engman 1986 as Part IV VFSMOD Appendices 110 Cover Manning s n range recommended Bare sand 0 01 0 013 0 011 Bare clay loam eroded 0 012 0 033 0 02 Fallow no residue 0 006 0 16 0 05 Range natural 0 01 0 32 0 13 Range clipped 0 02 0 24 0 10 Grass bluegrass sod 0 39 0 63 0 45 Short grass prairie 0 10 0 20 0 15 Dense grass 0 17 0 30 0 24 Bermuda grass 0 30 0 48 0 41 Weeping lovegrass bluegrass buffalo grass blue gramm grass native grass mix OK alfalfa lespedeza 3 3 Vegetation types for VFS s The following data on vegetation is taken from Haan et al 1994 Vegetation good stand Density Grass spacing Maximum Modified n stems m S cm height H cm ny VEGETATION TYPICALLY RECOMMENDED FOR VFS Yelow bluestem 2700 1 9 Tall fescue 3900 1 63 38 0 012 Blue gramma 3750 1 65 25 0 012 Ryegrass perennial 3900 1 63 18 0 012 Weeping lovegrass 3750 1 65 30 Bermudagrass 5400 1 35 25 0 016 Bahiagrass 20 0 012 Centipedegrass 5400 1 35 15 0 016 Part IV VFSMOD Appendices 111 Vegetation good stand Density Grass spacing Maximum Modified n stems m S cm height H cm Hy Kentucky bluegrass 3750 1 65 20 0 012 Grass mixture 2150 2 15 18 0 012 Buffalograss 4
79. dist parms m o o o y 1 bes o 6 2 0 125 0 08 0 92 1000 Rainfall mm and Buffer Length m gt base uh sample2 lis base vfs sample3 prj 80 8 655 retv CN uhk uhe uhp isoks dp isothetai igrss FldROmm FldROnG VFSROM VFSROMO VFSINFW3 FldSEDkg FldSEDconc VFSSEDkg VFSSEDconc SDR RDR O 72 48 7 6 4 788 1 125 2 2 23 03 1151 566 22 97 1149 131 4 512 11378 57 9 08 10538 32 9 17 926 998 O 78 90433 48 7 6 4 31937770644205 1 194607844644722 2 2 33 07 1653 398 33 03 1652 380 3 095 18668 36 11 30 16990 10 10 28 909 999 O 69 857995 48 7 6 5 99311607063443 1 231331036926668 19 92 996 200 19 83 992 093 6 184 9263 38 9 90 8445 28 8 51 912 996 O 64 15999 48 7 6 4 43821602222873 1 129906675715504 2 2 42 29 2114 537 42 23 2112 733 3 881 25368 50 12 00 22964 22 10 87 905 999 O 63 25702 48 7 6 5 2101015792397 1 107435056803315 2 2 40 61 2030 425 40 54 2028 087 4 416 24358 47 12 00 22558 27 11 12 926 999 O 67 9788675 48 7 6 4 09487041403889 1 132144779484306 2 2 18 02 900 963 17 96 898 327 4 313 8110 35 9 00 7307 54 8 13 901 997 O 69 95708 48 7 6 5 08092196668909 1 153272789480338 2 2 20 99 1019 719 20 31 1016 193 5 603 9564 48 9 40 8763 87 8 62 914 997 O 72 1181 48 7 23 11 1155 592 23 04 1152 600 5 070 11454 00 9 91 10613 41 9 21 92 99 O 61 529265 37 52 1676 015 37 45 1873 699 4 393 21948 08 11 70 20204 91 10 78 921 999 O 83 398785 48 7 6 4 15675089300624 1 213208992506
80. e filenames will cause unpredictable results For example my Project prj will cause problems Use something like my_Project prj this should work fine Part III VFSMOD W User s Manual 97 12 VFSMOD W Change History 11 18 2000 Added buttons in VFSMod Output Viewer for the remaining Output files ohy ogl og2 Made Nprop global and now the number of segments in the segment properties window updates when the user deletes and adds segments 2 5 2001 The first level of the output filenames default to the same as the project name The user can override this by changing the output filenames In the igr files a check is made when the user changes the VL buffer length The new buffer length is checked against the segment properties If these are unequal a warning message box is displayed and the View Edit Segment properties window is opened 3 5 2003 vfsmod w exe version 2 00 xx UH exe version 1 06 vfsm exe version 1 06 Major revisions for the entire system Adding a number of buttons on pages to dupli cate menu selections Added Sensitivity Analysis Added Uncertainty Analysis Added Design Analysis 5 20 2003 NEW FEATURES IN RELEASE V2 2 XX New more intuitive menu labels and lay out Expanded and improved sensitivity and uncertainty analyses procedures Individual fil ter areas or combines source filter areas can be now analyzed individually Multi dimensional analysis is also available as
81. ection to match hyetograph file sample2 hyt Ea ka ka Fa Fa OO Nh A DO e0o00o0o0oo0oco0 coo C00 00 00 CC CCOCORRRENN WA GN 2 743 File output sample2 hyt SCS 10 MIN HYETOGRAPH No Time hr 0 167 IID 500 667 833 000 167 AN DAG WHE RROOWOO 80 000 unah kh khk khkk 9159 5479 2642 1361 2059 4933 0018 7230 6414 273455 9899 3475 8800 4790 41579 9024 7004 5415 4171 3201 2449 1868 1421 1078 0815 0615 0463 0348 0261 0195 0146 0108 0081 0060 0044 0033 0024 h 000 3 257 RD 0 000 440 728 867 021 194 388 WoN A GW 0o NS 000 2 743 h Rainfall mm Rain30 mm 0 199 241 287 338 396 460 533 UH v1 06 3 2002 Part II VFSMOD and UH User s Manual 62 9 1 5333 10 1 500 11 1 667 12 1 833 13 2 000 14 2 167 15 2 333 16 2 500 17 2 667 18 2 833 19 3 000 20 B67 21 32333 22 3 500 23 3 667 24 9 623 25 4 000 26 4 167 27 4 333 28 4 500 29 4 667 30 4 833 31 5 000 32 Ta LEI 33 Ie 333 34 5 500 35 5 667 36 5 833 37 6 000 Computed Total Rain Actual Total Rain raimax30 I30 616 z413 828 967 138 S357 650 070 740 067 832 564 067 740 070 650 J357 138 967 828 27313 616 533 460 396 338 287 241 2199 RRR ka ka ks ka ka Ra RH Lt DS NH WH WH ORD G WH WN NH No S bea b Fa 102 102 36 72 608 862 158 509
82. ediment parameters these can be chosen from soil texture using tables from the manual The structure of these files 1s discussed in detail in Part II Section 1 4 on page 44 Part I VFSMOD W Model Documentation 11 3 UH utility preparation of model inputs for design purposes As an aid to set up the model inputs the distribution package includes an utility UH that creates synthetic model inputs for the upslope source area based on the NRCS SCS design storm for a given location and soil type The utility implements the NRCS SCS curve number unit hydrograph and Modified Universal Soil Loss Equation MUSLE concepts to produce ready to use input files for VFSMOD These inputs are rainfall hyetograph field inflow hydrograph and field sediment inflow and characteristics UH and VFSMOD are intended to be run in sequence for a design case After running UH the remaining VFSMOD inputs needed pertain only to the vegetative filter strip characteristics dimension soil vegetation and numerical solution parameters The structure of UH input and output files is discussed in Part II Section 2 3 on page 59 The following sections herein present the theory behind the methods implemented in UH 3 1 Generation of Synthetic Rainfall Hyetographs 3 1 1 Equations for storm types II amp III For storm types II and III the equations presented by Haan et al 1994 are used to generate the hyetographs The equation is PO 5954 T 2401
83. elected Output produces Part III VFSMOD W User s Manual 88 li Sensitivity Plot for Curve Number f JE o x Curve Number Filter Length 20 m Rain 151 1 mm Base value 75 Range 75 to 95 in increments of 1 Source Runall imm a wp Sampled Mean 109 321 90 Sampled Std Dev 16 8597 80 76 78 80 82 84 86 88 90 92 94 96 Ov 15 4 Curve Number Dismiss Other plotting and summary options include Plot Selected Output Absolute Sensitivity This produces a plot of slope of the output versus the input example Slope of Source Runoff versus CN Plot Selected Output Relative Base Sensitivity This produces a plot of Output BaseOutput Input BaseInput BaseInput BaseOutput versus the Input Plot Selected Output Relative Sensitivity This produces a plot of slope of the output versus the input times Input Output versus the Input Output Sensitivity Results This produces an output file with all of the statistics Here are examples for each of these Plot Selected Output Absolute Sensitivity a Absolute Sensitivity Plot for Curve Number ji i o x Curve Number Source Runoff mm Filter Length 20 m Rain 151 1 mm 3 0 Base value 75 gt 29 s u F 28 Range 75 to 95 in increments of 1 3 27 Mean Abs Sen 2 728 26 Std Dev Abs Sen 0 1253 25 76 78 80 82 84 86 88 90 92 94 Ov 76 Abs Sen 4 6 Curve Number Dismiss Plot Selected Output
84. ense of more simulation run time Instabilities can also be avoided by reducing increasing the number of nodes in the domain N b With large sediment input into the filter strip the program blows up Set ICO 0 In this case the sediment deposition is so large that the change in the nodal slope in the downstream face of the wedge creates problems to the finite element flow Part II VFSMOD and UH User s Manual 50 solution Petrov Galerkin does well but it does not perform miracles on a drastically changed domain Setting ICO 0 ignores the changes in slope and allows the simulation to be completed Previous comparison by the authors between runs with ICO 1 or 0 show that difference in results sre typically in the rage of 5 10 c Assigning values to KPG NPOL The order of the shape function used in the numerical solution finite elements can be set to linear NPOL 2 quadratic NPOL 3 or cubic NPOL 4 Please note that if the order of the function is changed to any other type than quadratic recommended the regular finite element formulation will be run instead of the improved Petrov Galerkin method One could also select a regular quadratic finite element by setting KPG 1 Tests made during program development show the increase in execution time induced by selecting the PG method are small as compared with the gains in stability and accuracy obtained Thus the setting NPOL 3 and KPG 1 are recommended d Assigning values to N The
85. er Output Information Part 2 Joutput samp e2 hyt dian ae Option buttons provide shortcuts to the UH menu entry these include the buttons Run This Project executes the current project Graph Hyetograph produces bar graphs of rainfall intensity versus time the user selects the output rainfall hyetograph file irn Graph a Runoff Hydrograph oproduces a runoff hydrograph the user selects the runoff file iro View Output Files opens a text window with a user selected output file Part III VFSMOD W User s Manual 71 Inputs Outputs inp inputs for the source area for UH irn rainfall hyetograph input for vfsmod runoff hydrograph from the source iro area input for v smod sediment properties for the sediment isd filtration submodel summary of the inputs and outputs out from UH detailed summary of of MUSLE calculations and the runoff hyt hydrograph For Tips on running troubleshooting VFSMOD see section in Part II 4 1 UH Input File Editing uh Editing inputs sample2 5 x Input Filename finputs sample2inp 25 Reinfall mm 85 Curve Number 10 Length m 5 Area ha fo Slope 6 Storm Duration h Storm Type 25 Soil Erodibility K 1 Crop Factor C Clay z SPUTES R dp Particle Class 1 Practice Factor P h Diameter cm 2 200 10 4 or 1 for table value Rainfall Factor R Williams Recommended Gave Savo and Close
86. es from incoming sediment with diameter gt 0 0037 cm coarse fraction that will be routed through wedge unit fraction i e 100 1 0 CI incoming flow sediment concentration g cm POR porosity of deposited sediment unit fraction i e 43 4 0 434 DP sediment particle size diameter ds cm read only if NPART 7 SG sediment particle density y g em read only if NPART 7 1 4 6 3 File example 4 1 0 0 034 434 0013 2 65 1 5 Model file outputs The program writes output into ASCII files Each aspect of the model is written to different files The model outputs include information on the water balance volume of rainfall field inflow filter outflow and infiltration hydrograph sediment balance field inflow filter outflow and deposition sedimentograph filter trapping efficiency and sediment deposition pattern within the filter The output files contain summaries of the main state variables in the program Note that these files are created in the output directory at run time every time the model is run and that the actual file names are given by substituting filename by the name of the set selected at the command line If you wish to keep the results from different simulations it is advised that you create a new set of input files with a different name for each case study The inputs and outputs included in these files are labeled in a verbose form to be self explanatory a filename ohy This file contains in
87. et to 0 if the precipitation is less than 0 2 of S This Part I VFSMOD W Model Documentation 14 assumes that the precipitation does not replenish the available storage ie 0 2 S 3 2 2 Peak flow calculation using NRCS method SI units Based on the triangular hydrograph assumption the time to peak can be stimated as D D ii FoU eoe 13 Where the concentration time can be estimated by the following equations SL Bate fig co ag EU 14 where ty is the transit time for each of the segments of the path between furthest point to the watershed outlet from a hydraulics point of view L and v are lengths and flow velocities for each segment The velocity can be estimated from Haan et al 1994 Table 3 20 pg 76 When there is little information on flow paths an alternative equation is used in UH Los 100 9 us CN te 15 4407 JY where f is in hours CN is the NRCS curve number L in m is the maximum linear distance to the watershed outlet Y m m is the average slope altitude difference between furthest point and outlet divided by L As a third option there are several simplified equations available such us Kirpich s 1940 t 0 01952 y 16 where f is in minutes The design peak flow TR55 method m s is calculated in UH as Ip AQF 17 where q is the unit peak flow n s ha mm A 1s the watershed area ha Q is the runoff volume mm and F is the ponding
88. f flow path 2 00 MUSLE type 2 where 1 Foster 2 Williams 3 GLEAMS See Manual Outputs Runoff volume 22 82 mm 1141 16 m3 Initial Abstraction 19 76 mm Concentration time 0 19 h 11 64 min Peak flow 0 3753 m3 s 27 0228 mm h Time to peak 0 65 h 38 76 min Hydrograph based on SCS unit hydrograph time h q m3 s 0 00 0 0000 0 06 0 0019 0 13 0 0178 0 19 0 0562 0 26 0 1139 0 32 0 7813 0 39 0 2472 0 45 0 3032 0 52 0 3440 0 58 0 3678 0 65 0 3753 0 71 0 3687 0 78 0 3511 0 84 0 3256 0 90 0 2953 wR OO 21 q mm h 0000 1366 2783 0434 2038 35 Ify 0501 7981 8278 24 26 27 2065 25 235 2d 7677 4836 0228 5477 2776 4442 2627 Part II VFSMOD and UH User s Manual 61 297 03 10 16 23 6 29 36 42 49 preys 62 68 74 81 87 94 00 07 PRI 20 226 33 239 46 M52 58 65 71 78 84 91 IT 04 T0 L7 S23 30 C CQ Co Co Co b lo lb lo No Nb Nb No Nb Nb Nb NP NP Nb Nb Nb ES Ea Ea Ea ka ES ES ki bk kk bk tk Sy 3 Gy SY S3 OV ONS Cy CX C089 G3 CX X O49 ASO OOS Cy SO OO OL OVO SOS OOS 2627 2298 1981 1686 1417 1180 0972 0795 0645 0519 0415 0330 0261 0205 0161 0125 0097 0075 0058 0044 0034 0026 0020 0015 0011 0009 0006 0005 0004 0003 0002 0002 0001 0001 0001 0000 0000 Time to ponding Duration of rainfall excess Time corr
89. factor that accounts for the percentage of the watershed with ponding or wetland conditions that will delay the overland flow Part I VFSMOD W Model Documentation 15 ponding area F p 0 1 00 0 2 0 97 1 0 0 87 3 0 0 75 5 0 0 72 q is calculated from t values using the following equation SI units q 4 3046 x 19 07 108 C logt 6 18 where log is the logarithm to the base 10 t is in hours Cy C and C are constants obtained from the following Table based on the ratio P and the 24 hour design storm type for the area Types I IA II IIT remember 0 2 S based on NRCS curve number method Storm I P Co C C I 0 10 2 30550 0 51429 0 11750 0 20 2 23537 0 50387 0 08929 0 25 2 18219 0 48488 0 06589 0 30 2 10624 0 45695 0 02835 0 35 2 00303 0 40769 0 01983 0 40 1 87733 0 32274 0 05754 0 45 1 76312 0 15644 0 00453 0 50 1 67889 0 06930 0 0 IA 0 10 2 03250 0 31583 0 13748 0 20 1 91978 0 28215 0 07020 0 25 1 83842 0 25543 0 02597 0 30 1 72657 0 19826 0 02633 0 50 1 63417 0 09100 0 0 II 0 10 2 55323 0 61512 0 16403 0 30 2 46532 0 62257 0 11657 0 35 2 41896 0 61594 0 08820 0 40 2 36409 0 59857 0 05621 0 45 2 29238 0 57005 0 02281 0 50 2 20282 0 51599 0 01259 III 0 10 2 47317 0 51848 0 17083 0 30 2 39628 0 51202 0 13245 0 35 2 354
90. formation related to the hydrology side of the problem overland flow and infiltration The content of this the file is controlled by the input parameter IELOUT The first part of the file summarizes information read from the ikw iso and irn input files along with some of the calculated parameters needed for the simulation The second part of the file contains the inflow hydrograph from iro rainfall excess ie calculated with the Green Ampt model and the output hydrograph from the filter Only 100 time steps are printed to this file each one is the average of the precedent NWRITE steps where NWRITE NDT 100 b filename og1 Part II VFSMOD and UH User s Manual 49 The file contains information related with the sediment filtration model The first part of the file summarizes information read from the igr and isd input files along with some of the calculated parameters needed for the simulation The second part of the file contains sediment transport and deposition time series for the simulation period As before only a 100 time steps are printed to this file In this case the sediment filtration step is calculated with the average flow conditions calculated as described above c filename og2 This file contains the flow characteristics at the singular points 1 3 in and out as defined in Part I of this manual of the filter for the simulation period for the same 100 steps described above d filename osm This file
91. from thousands of site years of observed erosion rates around the world The equation is given by A RKLSCP 27 A soil loss average over the slope length R 7 combined erosivity of rainfall and runoff see section 3 3 2 K soil erodibility factor determined as the soil loss from a unit plot with dimensions 22 m 73 feet on a 9 slope tilled up and down slope with tillage periodically to prevent surface crusting and weeds LS topographic factor based on the lenght and slope and is computed as where slope length in m and n slope length exponent which is 0 5 for slopes gt 4 0 4 for slopes between 3 and 4 and 0 3 for slopes lt 3 Part I VFSMOD W Model Documentation 21 S Slope factor calculated as S 65 45 4 565 0 065 where s sin 0 0 slope angle C cover management factor ratio of soil loss from the particular cover management to that of the unit plot dimensionless P conservation practice factor ratio of soil loss from the practice to that of the unit plot dimensionless The unit plots were defined as 22 m 73 feet in length 996 slope tilled up and down the slope periodically to prevent surface crusting and weeds The values L S C and P are referenced to this standard plot For example a C 0 5 indicates that one would expect about one half the erosion with this cover management than from the standard plot Since the USLE is applicable to areas dominated by overland flow
92. g the run a set of the VFSMOD inputs is created in the INPUTS subdirectory sample2 irn sample2 iro sample2 isd sample2 iso Two more output files are created in the OUTPUT subdirectory that summarize the calculations performed sample2 out and sample2 hyt The content of these files is produced in verbose mode and is self explanatory Note that two more files are needed to run VFSMOD filter characteristics files ikw and igr and they are not created by UH but the user needs to set them up from field data To continue the example given above one could copy the sample files included in the distribution package sample ikw and sample igr into sample2 ikw and sample2 igr in the INPUTS subdirectory VFSMOD is now ready to be run by issuing the command Part II VFSMOD and UH User s Manual 57 vfsm sample2 2 2 Using the project file for input and output Another way to complete the example would be to create a project sample file that includes the newly created sample2 files and specifies sample igr and sample ikw as igr and ikw files see Section 1 3 on page 42 An example of a project file sample lis for UH is given in the following Table Unix Windows 9x NT 2000 XP inp inputs sample inp inp input sample inp iro inputs sample iro iro inputs sample iro irn inputs sample irn irn inputssample irn isd inputs sample isd isd inputs sample isd out output sample out out output sample out hyt output sample hyt hyt output sample hyt The p
93. ge between submodels Flow conditions at the entry exit and three inner points 1 2 and 3 of the filter are needed for the sediment transport calculations q qj 72 73 and qout in Figure 3 The GRASSF and SEDIMOT II models use a simple approach to calculating those values and do not consider the complex effects of rainfall infiltration and flow delay caused by the filter A more accurate description of the flow conditions are obtained from the hydrology submodel presented above In turn the sediment transport model supplies information on changes in surface conditions topography roughness due to sediment deposition during the event that affect overland flow This interaction between submodels is depicted in the flowchart in Figure 4 Rainfall A rainfall infiltration ak Sediment Transport Field water a i he MESE sedi inflow AE q Tov ode iid water outflow Figure 4 Flowchart showing linking between hydrology and sediment submodels During the simulation feedback between the hydrology and sediment models is produced The hydrology model supplies the flow conditions at the five locations entry 1 2 3 and exit set in the last time step Figure 3 The other parameters that interact through the linkage are the length slope and roughness in each of the sections entry 1 2 3 and exit After solving the sediment transport problem for a time step new values of roughness and or slope are
94. hod Calculate time of concen tration Peak Flow Time to Peak by SCS TR55 Create Runoff Hydrograph from SCS unit hydrograph Develop Las hyeto graph from SCS storm type Calculate Storm erosion using MUSLE amp average Sediment Concentration in Runoff Write Input Files for VFSMOD Figure 12 Computations in UH 3 5 Sensitivity Analysis of VFSMOD A sensitivity analysis was performed to gain some insight in the dependence of model outputs on certain model parameters and to assist in the model calibration Mufioz Carpena et al 1999 The study showed that the main parameters controlling the hydrology outputs were soil hydraulic conductivity and initial water content whereas the model was fairly insensitive to changes in saturated water content and suction at the wetting front values Previous research Mufioz Carpena et al 1993a showed that Manning s surface roughness controls mainly the time to peak of the outgoing hydrograph Testing on the sediment component of the model showed that the main parameters controlling sediment outflow are media spacing and particle diameter Variations in the Part I VFSMOD W Model Documentation 26 modified Manning s roughness had relatively little effect on the output and the effect of media height was only visible for large events when the filter began to be inundated with sediment 3 6 Previous Testing and Applications VFSMOD was tested with natural events data at a
95. ich 1990 KINEROS A Kinematic Runoff and Erosion Model Documentation and User Manual USDA ARS ARS Pub no 77 Zhang Q C G Okoren and K R Mankin 2001 Modeling Fecal Pathogen Transport in Vegetative Filter Strips American Society of Agriculture Engineers Sacramento Cal ifornia Paper of ASAE no 01 2194 ASAE St Joseph Part I VFSMOD W Model Documentation 39 Part II VEFSMOD and UH User s Manual 1 VFSMOD user s manual 1 1 Obtaining VESMOD VFSMOD documentation source code and binaries for a number of platforms can be obtained in digital format through internet at the following URL site USA http www3 bae ncsu edu vfsmod The files are in ZIP tar gz compressed format All necessary files to compile and run a sample application are included Please select Windows 9x NT 2000 XP vfsmodpc zip for the command line version or vfsmod w install zip for the graphical user interface or UNIX vfsmodux tar gz versions as needed If you do not have an internet connection you can contact the authors for assistance 1 2 Installing and running VFSMOD VFSMOD and UH source code is distributed both in Windows 95 98 NT 2000 XP and UNIX versions along with make files and sample input and output files The source code is written in standard FORTRANT7 so that compilation should be straight forward following the included makefile and using the proper set of files for each platform Windows 9x NT 2000 XP or UNIX Binaries for
96. ify the parameters to define the distribution For the UH uncertainty analysis Curve Number CN Soil Erodibility Factor K Crop Factor C and the Practice Factor P can be selected The user selects the parameters to consider using the Check boxes and selects the probability distribution Currently the normal log normal triangular and uniform are available After selecting the distribution the Set Parameters button opens the window to enter the parameters defining the distribution For the normal and log normal distribution the mean and standard deviation are entered The peak and maximum and minimum values specify the triangular distribution The minimum and maximum values determine the range for sampling the uniform distribution If the user would like to also do the uncertainty analysis for the VFSMOD parameters they can switch to the VFSMOD screen 5 RITE Uncertainty Parameter Selection Uncertainty Selections for Source Area Base Project Files scll lis After Selecting the Distribution Parameters Base Values Distribution Click on the Button to setthe parameters V Curve Number CN a5 Triangular z Soil Erodibiliy K 33 Select Distribution Sal Pocus Crop Factor C fi Select Distribution ES lojx Triangular Distribution Parameters for Practice Factor P fi Select Distribution Samples 10 t VF Set VFE Peak 5 Load A Different Minimum Do Simulations Base Project Cance
97. ight of way 76 85 89 91 Dirt including right of way 72 82 87 89 Western desert urban areas Natural desert landscaping pervious 63 77 85 88 areas only Artificial desert landscaping impervious 96 96 96 96 weed barrier desert shrub with 1l to 2 inch sand or gravel mulch and basin borders Urban districts Commercial and business 85 89 92 94 95 Industrial 72 81 88 91 93 Residential districts by average lot size 1 8 acre or less town houses 65 77 85 90 92 1 4 acre 38 61 75 83 87 1 3 acre 30 57 72 81 86 1 2 acre 25 54 70 80 85 1 acre 20 51 68 79 84 1 Average runoff condition Ia 0 2S Part IV VFSMOD Appendices 113 Cover Description Curve Numbers for hydrologic soil group Average x percent Cover type and hydrologic condition impervious A B C D area 2 acres 12 46 65 77 82 Developing urban areas Newly graded areas pervious areas only 77 86 91 94 no vegetation Idle lands CN s are determined using cover types similar to those in table 2 2c a The average percent Impervious area shown was used to develop the composite CN s Other assumptions are as follows impervious areas are directly connected to the drainage system impervious areas have a CN of 98 and pervious areas are considered equivalent to open space in good hydrologic condition CN s for other combinations of conditions may be c
98. iment filtration submodel soil properties for the infiltration submodel ogl og2 ohy osm osp detailed time series describing the sediment transport and deposition within the buffer detailed information on the singular points defined in the theory section of the manual detailed outputs on the inflow and outflow hydrographs detailed summaries of the water and sediment balance final geometry of the filter overall summary of filter performance with comparisons between the source area and filter Part II VFSMOD and UH User s Manual 43 1 4 VFSMOD input files All files are in FORTRANT7 free format The inputs are distributed among 6 files filename ikw parameters for the overland flow solution filename irn storm hyetograph filename iro runoff from the adjacent field into the VFS filename iso soil properties for the infiltration model filename igr buffer properties for sediment filtration model filename isd sediment properties for sediment filtration model Note that filename could and should be replaced by any other name you would like to identify the case study with max 25 characters with the only condition that all six files must be in the inputs subdirectory The name of the input file set to process is selected at the command line and the output file set is created automatically using the name given as input In this way different problems can be run from the same direc
99. inputs for VFSMOD 59 2 4 Sample application 2755 cn Otho gebe er o tbe qe ed 60 Part III VFSMOD W User s Manual csccssccessccsssscssccssccesecessscessccssceesasesnessecesaces 66 1 Installation Information decidido d pa c ere obti bbc uius rit 66 2 Using VESMOB 4s sederit cee d riot preti a to itu t ad ree ber ono que 68 3 Mam Window OR E O RE E A E E 69 3 1 vfsmod w Options File cccccssecsecsseeeceecesceeceseeceeesceseecsecseecsecsaeeaecaeeesereeseeneeeneeaeenees 70 4 UH Project WANA OW gat Stato alos eed tel aee ele Sae Tu 71 4 1 UH Input File Editing x iere tere be RR E RE RI e EL dE 72 5 VES Project WIC OW o eaae naa pe a doct hood ea ipai qi AUI dt adeo didus 74 5 1 Overland Flow Inputs ikw eese enne 75 5 2 VFS Infiltration Soil Properties 1S0 eee 77 5 3 VFS Buffer Vegetation Characteristics igr sess 78 5 4 Incoming Sediment Characteristics 1sd sse 78 5 5 Storm Hyetograph Itn reete e a ac nies Duin eee el 79 5 6 VFS Source Area Storm Runoff iro sss eren 80 6 Processing and Analysis of VFSMOD Results sseesseeeeeeee 82 7 Using the Plot Windows x0 oaensepa tete eet da E ER E ts 84 8 Sensitivity Analysis SOreeris iiec reet e redes ta ee Y eh ee ee D er ev cadet 86 9 Uncertainty Analysis Screens Losses reste etr os pup ducti axle aa Le S eer ae 91 10s Design Screen s aisha a utem bts
100. ions where a portion of the sediment is deposited in the field area adjacent to the filter After the wedge has formed no sediment is deposited in zone A t and the initial load g moves through to the next zone B t In this zone deposition occurs uniformly with distance to the deposition edge with transport mostly as bed load The model assumes that the sediment inflow load g is greater than the downstream sediment transport capacity g at point 2 Figure 3 The algorithm calculates the g value for each time step and compares it with the sediment inflow load If g 4 gt Zsi all sediment is transported through the first part of the filter wedge g 4 and the sediment is filtered at the suspended sediment zone lower part of the filter If g 2 deposition at the wedge occurs and the fraction not deposited is filtered at the lower part of the filter g g g 7 The calculation procedure utilizes a modified Manning s open channel flow equation continuity equation and Einstein s sediment bed load transport function Flow values at the filter entry and points 1 and 2 in Figure 3 dj qj q2 respectively are needed for these calculations After the downside of the wedge two zones C t and D t form the suspended load zone or effective filter length L t Figure 3 On zone C t sediment has covered the indentations of the surface so that bed load transport and deposition occurs but the soil slope S is not significant
101. ioz Carpena 2002 VFSMOD W a graphical Windows system for the evaluation and design of vegetative filter strips for sediment trapping In Watershed Management to Meet Emerging TMDL Environmental Regulations Proc 11 13 March Fort Worth Texas USA eds A Saleh B Wilson pp 532 535 St Joseph Michigan ASAE Rawls W J and D L Brakensiek 1983 A procedure to predict Green Apmt infiltration parameters Adv in Infiltration pp 102 112 ASAE Pub no 11 83 Skaggs R W and R Khaheel 1982 Chapter 4 Infiltration In Hydrologic modeling of small watersheds Ed by C T Haan H P Johnson and D L Brakensiek ASAE Monograph No 5 American Society of Agricultural Engineers St Joseph MI pp 121 168 Suwandono L J E Parsons and R Mufioz Carpena 1999 A design guide for vegetative filter strips using VFSMOD Presented at the 1999 ASAE CSAE Ann Intl Meet ing 19 20 July Paper 99 2147 ASAE St Joseph MI Tollner E W B J Barfield C T Haan and T Y Kao 1976 Suspended sediment filtra tion capacity of simulated vegetation Transactions of ASAE 19 4 678 682 Tollner E W B J Barfield C Vachirakornwatana and C T Haan 1977 Sediment deposi tion patterns in simulated grass filters Transactions of ASAE 20 5 940 944 USDA NRCS 210 VI TR 55 2nd Edition June 1986 U S NRCS Formerly Soil Conservation Service National Engineering Handbook Hydrology Section 4 1972 and USDA ARS 41 172 1970
102. is directory would contain D vfsmod Vfsmod w exe Graphical user interface Vfsmod w hlp Windows Help file Uh exe Utility program UH Vfsm exe Vegetative filter strip model vfsmod Sample2 lis Sample project for UH Sample prj Sample project for vfsmod Readme txtThis information Documentation Vfsm pdf the Users Manual Inputs Directory containing the inputs Sample igr Sample Overland flow inputs for VFSMOD Sample ikw Sample Buffer vegetation inputs for VFSMOD Sample irn Sample Rainfall hyetograph for VFSMOD Sample iro Sample Runoff hydrograph for VFSMOD Sample isd Sample Incoming sediment characteristics for VFSMOD Part III VFSMOD W User s Manual 66 Sample iso Sample2 igr Sample2 inp Sample2 iso Output Sample2 out SourceCode Uh Vfsm Sample Infiltration soil properties for VFSMOD Sample overland flow inputs created by UH Sample inputs for UH Sample infiltration soil properties created by UH Directory containing the outputs from UH and VFSMOD Sample output from UH used as a placeholder FORTRAN source code for UH FORTRAN source code for VFSMOD And after your first execution of vfsmod w then the Options file is written to this directory vfsmod w cfg The Directory for Saving Project Files should be D vfsmod After this is done vfsmod w should be ready to analyze your vegetative filter strips Part III VFSMOD W User s Manual 67 2 Using VFSMOD How Can the Model be Used Thi
103. l Maximum Done Curve Number Similar to the UH uncertainty selection screen only selected parameters are available for uncertainty analysis for VFSMOD Currently the parameters are the saturated vertical conductivity and initial water content for the Green Ampt infiltration submodel for the filter strip and the Dp Particle Class diameter and SS Media Element Spacing parameters Selection of each parameter is done with the Check boxes and setting the distribution Currently the normal log normal triangular and uniform are available After selecting the distribution the Set Parameters button opens the window to enter the parameters defining the distribution For the normal and log normal distribution the mean Part III VFSMOD W User s Manual 91 and standard deviation are entered The peak and maximum and minimum values specify the triangular distribution The minimum and maximum values determine the range for sampling the uniform distribution On either of the screens the number of simulations is also specified These will typically range in the thousands although the user can specify any number On a Pentium IH 1 GHZ processor based desktop each simulation takes from 10 15 seconds up to as much as 1 minute lol xl a VFSMOD Uncertainty Parameter Selections Uncertainty Selections for Buffer Area Log Simulation Information Current Project Files sample prj After Selecting the Distribution Click on
104. l International Meeting Chi cago Illinois Paper 02 2133 ASAE St Joseph MI Knisel Walter G F M Davis R A Leonard 1992 GLEAMS Version 210 Users Man ual Pre Publication Copy US Department of Agriculture Agricultural Research Ser vice Available from University of Georgia Coastal Plain Experiment Station Bio and Ag Engineering Tifton GA UGA CPES BAED Publication No 5 259 pp Lighthill M J and C B Whitham 1955 On kinematic waves flood movement in long rivers Proc R Soc London Ser A 22 281 316 McCuen R H W J Rawls and D L Brakensiek 1981 Statistical Analysis of the Brooks and Corey and the Green Ampt parameters across soil textures Water Resour Res 17 4 1005 1013 Mein R G and C L Larson 1971 Modelling the infiltration component of the rainfall runoff process Bulletin 43 University of Minnesota MN Water Resources Research Center Mein R G and C L Larson 1973 Modeling infiltration during a steady rain Water Resourc Res 9 2 384 394 Morgan M G and M Henrion 1990 Uncertainty Cambridge University Press Cam bridge MA Mufioz Carpena R 1993 Modeling hydrology and sediment transport on vegetative filter strips Ph D dissertation North Carolina State Univ Raleigh Muiioz Carpena R C T Miller and J E Parsons 1993a A quadratic Petrov Galerkin solution for kinematic wave overland flow Water Resour Res 29 8 2615 2627 Mufioz Carpena R J
105. low needed at points 1 Q 9 see text L Lit Gout Figure 3 Filter description for the sediment transport algorithm The University of Kentucky algorithm considers that during a rainfall runoff event field runoff reaches the upstream edge of the filter with time dependent flow rate q cm s and sediment load g g cm s The vegetation produces a sudden increase in hydraulic resistance that slows the flow lowers its transport capacity g 4 g cm s and produces deposition of the coarse material particle diameter d 70 0037 cm carried mostly as bed load transport The sediment trapped in this first part of the filter forms a geometrical shape that varies depending on the thickness of the deposited sediment layer at the entry of the filter Y t m and the effective top of vegetation H cm A triangular shape at the adjacent field area and the beginning of the filter is formed when Y t H After Y t H a Part I VFSMOD W Model Documentation 6 trapezoidal wedge is formed Figure 3 with three well defined zones the upslope face of the wedge with zero slope O t cm the upper face of the wedge parallel to the soil surface A t and the downslope face B t with an equilibrium deposition slope S for each time step Figure 3 Together these first filter zones are termed wedge zone and its length changes with time as sediment is deposited Zone O t external to the filter is important in explaining field observat
106. ly changed All bed load transported sediment is captured before reaching zone D t so only suspended sediment is transported and deposited in this zone until the flow reaches the end of the filter with sediment load g The sediment trapping algorithm for the suspended load zone follows Tollner et al 1976 equation based on a probabilistic approach to turbulent diffusion for non submerged flow Flow values at point 3 and filter exit g3 and qour respectively Figure 3 are needed for these calculations Details of the implementation of the submodel are given in Mufioz Carpena 1993 Under extreme sediment inflow events the filter can be filled up with sediment to the top of the standing vegetation VFSMOD accounts for this in a realistic way by allowing normal filtration up to the time step when the sediment wedge reaches the end of the filter X 2L and bypassing filtration from then on 2 g The original University of Kentucky sediment model uses a simple approach to calculate flow conditions at specific points of the filter and does not consider the complex effects of rainfall infiltration and flow delay caused by the buffer VFSMOD provides a more accurate description of the flow conditions from the hydrology submodel whereas Part I VFSMOD W Model Documentation 7 changes in surface conditions topography roughness due to sediment deposition during the event are obtained from the sediment filtration submodel 2 3 Linka
107. m 1 3 Flag to feedback the change in slope and roughness atthe sediment wedge ICO 0 or 1 0 Save Continue Editing Save and Close Close Help SS spacing of the filter media elements cm See Vegetation types for VFS s on page 111 VN filter media grass Manning s n See Vegetation types for VFS s on page 111 0 012 for cylindrical media s cm 3 H filter media height cm See Vegetation types for VFS s on page 111 VN2 bare surface Manning s n See Manning s roughness coeficient n on page 110 ICO integer flag to feedback the change in slope and surface roughness at the sediment wedge for each time step 0 no feedback 1 feedback See Tips for running the model on page 50 5 4 Incoming Sediment Characteristics isd V vfsm Editing E vfsmod w combo2 testgui inputs sample isd n x Incoming Sediment Properties file isd Jnputs sample isd m Sediment Properties Incoming flow sediment concentration 034 Porosity of deposited sediment 434 q cm 3 Cl fraction POR 1 Partion of Particles from incoming sediment Incoming sediment particle class th di gt 1 NPART ia with diameter gt 0 0037 cm Coarse ranges from 0 0 1 0 Sediment particle size diameter d50 0013 Sediment particle density g cm 3 cm DP read only if NPART 7 SG read only if NPART 7 2 85 Save Continue Editing Save and Close Close Help
108. m flow equation X mid point of downface of sediment wedge cm X bottom point of downface of sediment wedge cm X4 mid point of effective filter length L t cm and their associated NODEX i nodes for the X points to feed back to the overland flow submodel The procedure is as follows a find points for each of the areas in filter Part IV VFSMOD Appendices 105 b if required reshape the surface topography and roughness of the filter Notice that for entry a 0 slope value is not possible thus a minimum SCENTRY 0 005 is chosen The new values assigned are Section A slope Sc n VN bare Section B t slope Set n VN length VBT Sections C t amp D t slope unchanged n unchanged length VLT 1 25 KWWRITE N L M QTEMP X BCRO FWIDTH Write hydrology outputs to the ohy file as a hydrograph i e flow rate at the downstream end of the plane 1 26 OUTMASS VL FWIDTH TRAI LISFIL This subroutine processes the output hydrograph and calculates the components of the water and sediment balance The results are written to the summary file osm and osp Part IV VFSMOD Appendices 106 2 APPENDIX 2 Model parameters and variables 2 1 Overland flow A LJ B BCRO BCROFF 200 2 BCROFFQ C DPSI I DR DT DTC DX DR DX1 EK 1J EPS FK FR FWIDTH HMAX MAXITER MFLAG N NBAND NDT NELEM NL NMAX NPOL PGPAR I PSIM QK MAXEQN QM N QO N QMAX R RNA I SOA I SR SW
109. mpt window under Windows 9x NT 2000 XP 40 1 2 2 xr together with the Windows Graphical Interface Windows 9x NT 2000 XP 41 1 2 3 Installing on a UNIX system oo cc isses eren 41 1 3 Using the project file for input and output 42 1 4 VESMOD input files 9 apetece ic p tura 44 1 4 44y filename ikw parameters for the overland flow solution 44 1 4 2 filename irn storm hyetograph ccecceeesecsecesceseeeeceseeeeceseeeeeesecaeeaecseeaeeneens 45 1 4 3 filename iro runoff from the adjacent field into the VFS ssuus 46 1 4 4 filename iso soil properties for the infiltration model 47 1 4 5 filename igr buffer properties for sediment filtration model 48 1 4 6 filename isd sediment properties for sediment filtration model 48 1 5 Model file outputs ieu etes eee e de i Ce e ERR 49 1 6 Tips for running the model 25 et ure ERU eR Redes 50 1 7 Sanple application 5 o e EE REC E dap deis 52 IS MENS EP mend sese 52 dE Cic 53 2 UH for Input Preparation User s Manual sseeeseeeenen 57 2 1 Installing and running UH t ees diit didt imi dtd 57 2 2 Using the project file for input and output essen 58 2 3 UH anp t files Rc RR EPA RENI RE ERIS RN 59 2 3 1 filename inp parameters for generating
110. n Research Project S 249 and S 273 f Univ of North Carolina Water Resources Research Institute g USDA CSREES and Southern Region Research Project S 1004 h Florida Agricultural Experiment Station FAES Part I VFSMOD W Model Documentation 35 10 References Abu Zreig M 2001 Factors affecting sediment trapping in vegetated filter strips simula tion study using VFSMOD Hydrological Processes 15 8 1477 1488 Abu Zreig M Rudra R P and H Whitley 2001 Validation of a vegetated filter strip model VFSMOD Hydrological Processes 15 5 729 742 Abu Zreig M R P Rudra and H Whitley 1999 Sediment trapping in vegetative filter strips Presented at the 1999 ASAE CSAE Ann Intl Meeting 19 20 July Paper 99 2078 ASAE St Joseph MI Arcement G J and V R Schneider 1989 Guide for selecting Manning s roughness coef ficients for natural channels and flood plains U S Geological Survey Water Supply Paper No 2339 Barfield B J E W Tollner and J C Hayes 1978 The use of grass filters for sediment control in strip mining drainage Vol I Theoretical studies on artificial media Pub no 35 RRR2 78 Institute for Mining and Minerals Research University of Kentucky Lexington Barfield B J E W Tollner and J C Hayes 1979 Filtration of sediment by simulated vegetation I Steady state flow with homogeneous sediment Transactions of ASAE 22 5 540 545 Barfield B J L G Wells and C T Ha
111. n b 1 0 1 16 SOLVE A B X N NBAND Solve the LUD transformed matrix A using a backward and forward substitution with A Xj b since A L U then L U X L U X L Y 5 b solving L Y b forward substitution U X y backward substitution 1 17 CONVER N X XM MFLAG This subroutine checks for convergence as max Xm 1 xm 10 8 max X A If there is convergence return MFLAG 1 otherwise MFLAG 0 1 18 UPDATE N X X0 Refresh values of the X vector this is xl x 1 19 FLOW N XT QT Calculate the flow vector at each iteration or time step by using Manning s equation Part IV VFSMOD Appendices 103 1 20 GRASSED TIME N QIN NODEX ICOARSE COARSE This subroutine is the driver for the sediment transport problem on grass filter strips Notice that all units are CGS system cm g s including Manning s n to follow the origi nal method as described by the authors Tollner et al 1977 Barfield et al 1979 Hayes et al 1979 1984 Wilson et al 1981 For computational purposes the filter is divided into the following sections notice the change in properties as sediment is deposited A t top flat face of sediment wedge B t downface of sediment wedge C t amp D t effective filter The calculation procedure is as follows a select flow and sediment load at filter entry If strip was filled up in a previous step NFUP 1 bypass sediment deposition calcula
112. nd crops present in the source study area for each of the design storms and soils selected for the analysis To do this the precipitation depths of selected return periods for the area along with the area s NRCS runoff and MUSLE erosion inputs are processed through the input preparation utility UH to create formatted inputs for VFSMOD hyetograph sample irn incoming sedimentograph sample isd and hydrograph sample iro With these inputs the VFSMOD model routes the incoming runoff and sediment and calculates water and sediment retained at the filter outflow and filter performance For this we must describe the actual vegetative filter strip characteristics to analyze for each design runoff event Usually the most relevant VFS characteristics to consider from a design prespective are soil type sample iso filter length uniformity and slope sample ikw and vegetation characteristics sample igr The VFSMOD sample project sample prj provided with the package installation for all platforms that can be used as a pattern and changed for each design run Information for standard USDA soil types Green Ampt infiltration inputs and vegetation covers spacing height to be used in the analysis can be found in this document For each combination of inputs a new project must be created and the model executed If the problem is to be prepared manually UNIX and DOS versions it is usually more efficient to create a naming convention for each
113. nfiltration Soil Properties file iso Jinputs sample iso r Green Ampt Infiltration Parameters Vertical Saturated K WKS 0000133 m s or 4788 cm h Average Suction atthe Wetting Front Sav m 37904 Volumetric Water Contents rcm 3 cm 3 Initial Water Content Ol 125 Saturated Water Content OS 311 Maximum Surface Storage SM m 0 Fraction of the filter where ponding is checked 0 lt SCHK lt 1 0 Save Continue Editing Save and Close Close Help saturated hydraulic conductivity K m s See Soils data Green Ampt parameters on page 110 Green Ampt s average suction at wet front m See Soils data Green Ampt parameters on page 110 saturated soil water content 0 m m See Soils data Green Ampt parameters on page 110 initial soil water content 0 m n maximum surface storage m relative distance from the upper filter edge where the check for ponding conditions is made i e 1 end filter 0 5 mid point 0 beginning Part III VFSMOD W User s Manual 5 3 VFS Buffer Vegetation Characteristics igr x vfsm Editing E vfsmod w combo 2 testgui inputs sample igr Buffer Vegetation Properties file igr jinputs sample igr Vegetation Properties Roughness Grass Manning s n YN Spacing for grass stems SS cm 22 s cm 1 3 12 04 Height of grass H crn 15 Roughness Bare surface Manning s n Vn2 s
114. nit9 g8 u183 91 3 87 8 655 57 0 5 0 8 350 3 1 14 0 61820 4 0 052778 1 23640 4 0 032639 1 85460 4 0 071528 2 47290 4 0 075000 3 09110 4 0 031944 3 70930 4 0 019444 4 32750 4 0 029885 4 94570 4 0 028947 5 56390 4 0 041667 6 18210 4 0 134028 6 80040 4 0 079167 7 41860 4 0 074306 8 03680 4 0 040972 8 65500 4 0 062346 Which corresponds to a filter on dense uniform bermuda grass with slope as follows 1 4 2 filename irn storm hyetograph 1 4 2 1 Structure of the file NRAIN RPEAK RAIN LJ J 1 2 1 4 2 2 Definition NRAIN integer number of rainfall periods including period to end simulation Part II VFSMOD and UH User s Manual 45 RPEAK maximum rainfall intensity for the storm m s RAIN LJ time s and rainfall rate intensity m s over the VFS for each period The last time step corresponds with the desired simulation time chosen by the user typically coupled with a rainfall intensity of 0 Note also that each time corresponds to the beginning of the rainfall period i e storm such as Period Time interval s Rainfal m s 1 0 0 to 299 9 1693E 05 2 299 9 to 599 8 6773E 05 3 599 8 to 900 0 1101E 04 Would be input as OOOOE 00 1693E 05 2999E 03 6773E 05 5998E 03 1101E 04 9000E 03 1947E 04 1 4 2 3 File example 12 1947E 04 0000E 00 1693E 05 2999E 03 6773E 05 5998E 03 1101E 04 9000E 03 1947E 04 1200E 04 1947E 04 1500E 04 152
115. nte evi ete EE EE en 103 1 17 CONVER N X XM MFLAQG voaa aa nnne enne n eren 103 1 18 UPDXATE NX X0 ctu tere ra a te aus 103 1 19 FLOWN A POT 2 5 scettr ciet Sint TERRE A EE 103 1 20 GRASSED TIME N QIN NODEX ICOARSE COARSE eene 104 1 21 OCF NPLACE ie ceti de TRY ERREUR CE e dea ai de ORE RE 104 1 22 EINSTEIN GS2 NTRCAP COARSE esee ene ener erre nnne enne 104 1 23 STEP3 GS2 TIME NTRCAP COARSE esssseseeeeeereeren eene nennen nnn 105 1 24 POINTS N XPOINTS NODEX VBT esee enne erret 105 1 25 KWWRITE N L M QTEMP X BCRO FWIDTH eere 106 1 26 OUTMASS VL FWIDTH TRALLISFIL seseseeeeeeeeeer eere 106 2 APPENDIX 2 Model parameters and variables esse 107 2 1 Overland flow esten BR d A MD 107 2 2 Infaltration i eee pH ROO e RR RETRO ERU 108 2 3 Sediment transport assout idet gave ev hae nee nO Hubs 109 3 APPENDIX 3 Soils and Vegetation data sse 110 3 1 Soils data Green Ampt parameters ssssssssesesseeeeenee eene enne 110 3 2 Manning s roughness coeficient n ssssssssessssseeeeeeeeneen enne 110 3 3 Vegetation types for VES s escena iE E de n ee Ru ee ER HR eres 111 3 4 NRGS SCS Curve Numbers 3 5 oet diter Beas eerte vtt edes uv oe 113 3 5 3 6 3 7 MUSLEE Grop factor eect c pte eese Contour factor P values for MUSLE equation in UH References for Soils and Vegetation data
116. ntent cumulative precipitation in m cumulative precipitation in m for last rainfall period total cumulative precipitation in m time s and rainfall rate m s over the VFS for each period cumulative runoff rate at the node without considering BCRO relative distance from de upper filter edge where the check for ponding conditions is made i e 1 end filter 0 5 mid point 0 beginning Maximum rainfall intensity for the storm Green Ampt s average suction at wet front m maximum surface storage m cumulative surface storage m Chu s 1978 tp and tp coefficients time to infiltrate surface ponded water Total cumulative rainfal m Saturated hydraulic conductivity m s Part IV VFSMOD Appendices 108 2 3 Sediment transport CDEP CI COARSE ICOARSE DF DEP DFS DP F FWID GAMMAW GAMMASB GSI GSSI GS2 GSO H NFUP NODEX J PART 1 PART 2 PART 3 POR QSED J RS RSS SE SS SC VLCM VM VMS VN VN2 XPOINTS J XT X1 YT Coefficient for reducing suspended sediment deposition in D t sediment inflow concentration g cm3 of coarse particles gt 37 microns in incoming sediment Flag 0 all particles fine lt 37 microns don t run the wedge part depth of flow at D t cm depth of sediment deposited in suspended sediment zone D t cm depth of flow at B t cm particle size diameter cm fraction trapped in the deposition wedge width of the strip cm FWIDTH
117. oc w combo2 testqui VFS Project File samplet pri Save Help Overland Flow Inputs finputs samp e ikw Edit Browse Infiltration Soil Properites finputs samp e iso Edit Browse Buffer Vegetation Properties finputs samp e igr Edit Browse Incoming Sediment Characteristics finputs samp e isd Edit Browse Storm Hyetograph finputs samp eim Edit Browse Source Area Storm Runoff finputs samp e2 iro Edit Browse Output is Proj El Sediment Transport burputsampie sg FST Flow through VFS oupusemple og Graph a Detailed Hydrographs Joutput samp Sony Dorint Water and Sediment Balances foutput samp seal use Sure Joutput samp e osp View Output Files The files used by VFSMOD are identified in the project window There are options to Save the project Edit any of the input files and Browse to Select different input files In addition any of the input or output filenames can be changed from this window Other options buttons provide shortcuts to the VFSMOD menu entry these include the buttons Run This Project executes the current project Graph a Sediment Runoff Balance produces bar graphs comparing sediment and runoff in and out of the filter strips the user selects the output summary file View Output Files opens a text window with a user selected output file As a feature if the user changes the project file name then the output file names are changed to the same first level name This feature can be overridden by
118. of the upstream portion in ha storm type storm type 1 1 2 1I 3 III 4 Ia D storm duration h L Length of the source area along the slope m Y Slope of the source area expressed as a fraction soiltype See Table for Acceptable Soil Types K Soil Erodibility If K 0 then K is computed based on texture and organic matter See REF Cfact C factor See Table in Appendix 3 Pfact P factor See Table in Appendix 3 leroty Select the method to compute the storm R factor in MUSLE not present or 1 selects Foster s Method 2 selects Williams method and 3 selects the CREAMS GLEAMS method Part II VFSMOD and UH User s Manual 59 The acceptable values for soiltype are Soil Types Case Sensitive Clay Silty clay Sandy clay Silty clay loam Clay loam Sandy clay loam Silt Silt loam Loam Very fine sandy loam Fine sandy loam Sandy loam Coarse sandy loam Loamy very fine sand Loamy fine sand Loamy sand Loamy coarse sand Very fine sand Fine sand Sand Coarse sand 2 3 1 3 File example file sample2 inp Clay n Aso Wes Sh Ose LO ake MOON O02 2 4 Sample application Table 1 Parameter values for the sample run Parameter P CN A storm type D L Y soiltype K Cfact Pfact Value 25 85 0 5 3 6 100 0 02 Clay 0 25 1 0 1 0 Parameter Description amount of storm precipatation in mm NRCS SCS Curve Number for the source area
119. om puted using area weighted averages for the CN s of the respective subareas Or see figures 2 3 or 2 4 TR55 document b CN s shown are equivalent to those of pasture Composite CN s may be computed for other combinations of open space covertype c Composite CN s for natural desert landscaping should be computed using figures 2 3 or 2 4 TR55 document based on the impervious area percentage CN 98 and the pervious area CN The pervious area CN s are assumed equivalent to desert shrub in poor hydrologic condition d Composite CN s to use for the design of temporary measures during grading and construction should be computed using figure 2 3 or 2 4 TR55 document based on the degree of development impervious area percentage and the CN s for the newly graded pervious areas Part IV VFSMOD Appendices 114 Runoff curve numbers for cultivated agricultural lands From USDA NRCS 210 VI TR 55 2nd Edition June 1986 Table 2 2b Cover Description Curve numbers for hydrologic soil group Cover Type Treatment n a A E e e condition Bare soil T 86 91 94 Fallow Crop residue cover CR Poor 76 85 90 93 Good 74 83 88 90 Straight row SR Poor 72 81 88 91 Good 67 78 85 89 SR CR Poor 71 80 87 90 Good 64 75 82 85 Contoured C Poor 70 79 84 88 Good 65 75 82 86 Row crops C CR Poor 69 78 83 87 Good 64 74 81
120. ot is copied to the Clipboard as a Windows Metafile wmf for optimum resolution Part III VFSMOD W User s Manual 84 The plot can also be printed by selecting the Print Plot button The plot can be previewed along with selecting the printer paper size and orientation V Print Preview Part III VFSMOD W User s Manual 85 8 Sensitivity Analysis Screens Sensitivity analysis can be done on a number of the input parameters for both the UH model and VFSMOD Set the ones you would like to analyze and leave the others unchecked S UH Paramater Selection ia mad UH Sensitivity Parameter Selections Set VFS Parameters Base Project Files scl lis UH Parameters Base Values Min Value Max Value Increment V Curve Number CN 85 5 Soil Erodibility K I CropFactor C fi n Practice Factor P 3 TIT Iii IT Load Different Do Simulations Base Project Cancel For the UH model sensitivity analysis can be done for Curve Number CN Soil Erodibility Factor K Crop Factor C and the Practice Factor P The user selects the parameters to consider using the Check boxes and enters the minimum maximum and an increment for the parameter The base value shown is the value in the base project files These values are used in some of the analysis screens In addition to setting the values the user can load a different base project and once the inputs are set do the simulation
121. ource Sediment Concentration a L c F VFSM Ksat Groen Ampl F Fiter nitretion n 3 Sediment Delivery Rato Fiter Source Plot Cumulative Probability C VESM Thelal Green Ampt Runot Delivery Reto Fiher Source Current Results File C VFSM Particle Class Diameter E MemodW combo VMestguoutpuflUncResuts by TUm ta Dismiss Results Based on 1502 Simulanons Examples of the frequency and cumulative probability distributions for sampling the curve number are shown below Part III VFSMOD W User s Manual 93 SDR Part III VFSMOD W User s Manual 94 10 Design Screen The design section of VFSMOD can be used to examine a range of storms and filter strip design parameters to assist in finding the optimum length for a given situation A base UH and VFSMOD project is selected The comparisons that can be included in the design are 1 a range of design storms for generating varying input runoff hydrographs and sediment loads ii arange of filter strip lengths and iii a range of filter vegetation density grass media spacing ii xl V Setup Design P Base Projects F ie Show UH Change UH Base UH Project File sample 2 lis Project Project Hide n es i Show VFS Change VFS Base VFS Project File samplel prj Project Project Hide Select the options for analyzing the effectiveness of a proposed vfs design Design Storm B Return Period T years Duration hrs R 2 5 10 25 100 Amoun
122. parsons g ncsu edu U ATO l MU up DES MEE E E LI EL TE l AAESIMIODSM a E Aci tcs More e Ad 1 Tabled f Contents esse iacet i decent n ipe doc peau uou O A use dined aka rns i Part I VFSMOD W Model Documentation scccsscesccesecsenecesencesccsscsensccssncesacssacees l 1 HNO INTER UNTEN EET l 2 VFSMOD Model Components Processes and Solution Techniques 3 2 1 Hydrology x ettet ted atus M Ata idu I RE 4 2 2 Sediment Eransport 5 aee a REOR EO UU EIER EE ERR 6 2 3 Linkage between submodels 3 eiii e idend 8 2 4 Solution procedure ERU I GR GRE EI EUER eid 9 2 5 Model inputs cce esee ee eade code eiecit 11 3 UH utility preparation of model inputs for design purposes ss 12 3 1 Generation of Synthetic Rainfall Hyetographs essere 12 3 1 1 Equations for storm types II amp III 12 3 1 2 Equations for storm types I amp IA ssssssssssessseseeeeeneeneeennn 12 3 2 Generation of Runoff Hydrographs sess 14 3 2 1 Computation of Total Runoff using NRCS Curver Number method SI units 14 3 2 2 Peak flow calculation using NRCS method SI units sss 15 3 2 3 Time correction for hydrograph to match hyetograph sss 19 3 3 Incoming sediment load calculation sseesessseeeeeeeeeeneeenneenn 21 3 3 1 Universal Soil Loss Equation
123. project that reflects the simulation run characteristics The proposed sequence is to prepare the UH inp input files combination of source area soils types and design storms first and then process them with UH to produce the corresponding VFSMOD inputs iso irn isd Afterwards the user creates the project files prj one per simulation as combination of the UH outputs and modification of the remaining input files igr ikw 1so as needed Each file must be then processed with VFSMOD and the SDR and RDR results obtained from the osm files From these outputs SDR or RDR versus filter length the user can obtain the optimal filter characteristics for each return period and soil type when overlaying the Part I VFSMOD W Model Documentation 30 pre defined sediment TMDL expressed in terms of a desired filter effectiveness 7o SDR or RDR In the MS Windows VFSMOD W modelling system versions 2 x and up this task is automated The projects for each combination of design inputs are automatically created within the program GUI after the user selects a range on the desired parameters This new version also automatically produces combined analysis output tables see Part III Section 10 on page 95 Additionally the program provides two powerful tools Once the optimal design parameters are selected an uncertainty analysis can be conducted using the graphical tools provided The objective of this analysis is to identify the
124. r can make graphs of various input and output parameters Each of the Plot windows offer option buttons to Copy the Plot to the Clipboard Edit the Plot or Print the Plot A plot of a runoff hydrograph is used as example to illustrate the various options V Runoff Hydrograph inputs sample iro 2192 1753 6 1315 2 876 8 Runoff ns 10 6 438 4 13 0267 19 728 26 gt 293 33 1307 39 832 46 5333 Time min Copy Plotto Clipboard Print Plot Edit Plot Selecting the Edit Plot button the plot can be customized The Axis titles can be changed along with setting the minimum and maximum values of the range along with how many labels A Title for the Plot can also be added The effect of these changes can be viewed by selecting the Preview Button S Graph Parameters lalxl Graph Title Y X Axis Y Axis Axis Title Time min Runoff m3 s 10 6 Minimum 1302666666 po o Maximum 4653333333 po Increment b b Preview Done Cancel Once Plot editing is complete the Plot can be Copied to the Clipboard The Plot can then be inserted into another application such as a word processor For example the plot can be inserted in Word by Selecting Edit Paste Special Picture or Device Independent Bitmap If you desire only the data used to create the plot then use Paste In Powerpoint use Paste Special and Device Independent Bitmap The pl
125. r manual for the command line versions of VFSMOD and UH is given in Part II along with annotated applications detailed description of input and output files and recommended input values Part III describes the integrated package VFSMOD W as a whole under the MS Windows environment Part IV contains appendixes with detailed description on model variables and a collection of tables with recommended inputs for a variety of soil climate and plant conditions Each Part builds on the previous ones Although the reader is encouraged to read through the sections in sequence to gain in depth knowledge of the system section II contains the essentials to run the MS Windows design oriented application Part I VFSMOD W Model Documentation 2 2 VFSMOD Model Components Processes and Solution Techniques VFSMOD is a field scale mechanistic storm based model designed to route the incoming hydrograph and sedimentograph from an adjacent field through a vegetative filter strip VFS and to calculate the outflow infiltration and sediment trapping efficiency The model handles time dependent hyetographs space distributed filter parameters vegetation roughness or density slope infiltration characteristics and different particle size of the incoming sediment Any combination of unsteady storm and incoming hydrograph types can be used VFSMOD consists of a series of modules simulating the behavior of water and sediment in the surface of the VFS The
126. rameters 2 develop probability distribution functions for each input parameter 3 randomly generate input parameter datasets based on the probability distributions 4 perform the model simulation with the randomly generated input dataset 5 repeat steps 3 and 4 for a large number of trials 6 generate probability distribution functions for the model outputs of interest and 7 use the output probability distribution functions to evaluate uncertainty in the model by placing confidence levels on the outputs Additional details on the application of this procedure can be found in Parsons and Mu oz Carpena 2001 Part I VFSMOD W Model Documentation 29 5 Design Procedure The design objective is to find optimal constructive characteristics length slope vegetation of a VFS to reduce the outflow of sediment from a given disturbed area soil crop area management practices to achieve a certain reduction in sediment i e that for TMDLs Proposed target outputs for analysis will be the sediment delivery ratio SDR and runoff delivery ratio RDR computed as SDR Mass of Sediment Exiting the Filter Mass of Sediment Entering the Filter RDR Runoff Exiting the Filter Runoff Entering the Filter From a design perspective we require the VFS to accommodate storms with return periods of at least 1 and 2 years and probably 5 and 10 years The first step in the analysis is to generate inputs into the VFS from the soils a
127. rent Issues Hints Problems and Workarounds 1 Q 3 4 5 6 7 8 Download the zip file containing the VFSMOD package vfsmod w install zip to your temp directory and unzip into a subdirectory After setup is complete you can delete the subdirectory You can delete the zip file but you may want to keep this in case you need to re install the program During setup you may receive a message that setup needs to update your system If you receive this message then allow setup to update your system After setup updates your system reboot and execute setup again In Windows 98 the MSDOS command window that vfsm exe and UH exe executes within is not automatically closed You should close this manually On some systems if you choose to install the package in drv Program Files then the execution menu may not work correctly for UH and VFSMOD We have seen this on Windows NT 4 0 systems The default install directory is c vfsmod To avoid this problem we recommend you use this directory If you have a previous version of vfsmod on your computer you should uninstall prior to installing this version With this version on Windows NT 2000 and XP you will need Administrator privileges to install A few system files are copied into the Windows System directories Since the vfsm and uh executables are written in Fortran and run at the Command window level all filenames should not contain any spaces Spaces in th
128. revision of the sediment filtration submodel to handle particle size distribution explicitly A submodel to handle sediment sorbed contaminants such as phosphorous Improvement of parameter estimation techniques calibration procedure and reduction of the uncertainty ranges of sensitive parameters Part I VFSMOD W Model Documentation 33 8 Distribution and Training The modelling system is provided free of charge to qualified users as an educational and research tool The model and documentation can be downloaded from the internet http www3 bae ncsu edu vfsmod or obtained from the authors Limited support is available from the authors Through the web site the user can send feedback and questions to the authors No formal training is available but can be arranged with the authors Part I VFSMOD W Model Documentation 34 9 Acknowledgments This work has been supported by the following programs and institutions a 1990 1993 Fellowship from INIA Agricultural and Food Research Institute of Spain Ministry of Agriculture in cooperation with USDA OICD and the NC State University b 1997 Study Leave for Researchers Program of INIA Agricultural and Food Research Institute of Spain Ministry of Agriculture in cooperation with USDA OICD and the NC State University c 1997 ICIA Agricultural Research Institute of the Canary Islands d North Carolina Agricultural Research Service e USDA CSREES and Southern Regio
129. rmation is included on the Options screen This information is stored in the file v smod w cfg in the installation directory For bug reports we may request that you e mail us this file to assist in debugging Part III VFSMOD W User s Manual 70 4 UH Project Window As an aid to set up the model inputs the distribution package includes a utility UH that creates synthetic model inputs based on the NRCS SCS design storm for a given location and soil type The utility implements the NRCS SCS curve number unit hydrograph and Modified Universal Soil Loss Equation MUSLE concepts to produce ready to use input files for VFSMOD These inputs are rainfall hyetograph field inflow hydrograph and field sediment inflow and characteristics The files used by UH are identified in the project window There is also options to Save the project Edit an input file and Browse Select a different input file In addition any of the input or output filenames can be changed from this window V uh Project sample2 lis lol xl Project Directory E vismod w combo2 testqui UH Project File sample2 lis Save Help UH Input File inputsXsemple2 inp Edit Browse Output Files Runoff Hydrograph for VFSmod finputs samp e2 iro Run This Project Rainfall Hyetagraph for VFSmod finputs samp e2 irn Graph a Hyetograph ISD Input file for VFSmod finputs samp e2 isd Graph a Runoff User Output Information Part 1 ouputisamp e2 out useless ll Us
130. rn conv till plow disk and harrow for seedbed cot cotton F rough fallow fld cult field cultivator G small grain GS grain sorghum M grass and legume meadow at least 1 full year pl plant RdL crop residues left on field RdR crop residues removed SB seedbed period sprg spring TP plowed with moldboard WC winter cover crop insignificant or an unlikely combination of variables b Dry weight per acre after winter loss and reductions by grazing or partial removal 4500 lbs represents 100 to 125 bu corn 3400 Ibs 75 to 99 bu 2600 Ibs 60 to 74 bu and 2000 Ibs 40 to 59 bu with normal 30 percent winter loss For RdR or fall plow practices these four productivity levels are indicated by HP GP FP and LP respectively high good fair and low productivity In lines 79 to 102 this column indicates dry weigth of the winter cover crop c Percentage of soil surface covered by plant residue mulch after crop seeding The difference betweenn spring residue and that on the surface after crop seeding is reflected in the soil loss ratios as residues mixed with the topsoil d The soil loss ratios given as percentages assume that the indicated crop sequence and practices are followed consistently One year deviations from normal practices do not have the effect of a permanent change Linear interpolation between lines is recommended when justified by field conditions See also footnote 7 e Cropstage periods are as defined on p
131. roject file in this example sample lis would be saved in the VFSMOD directory where the executable UH or UH EXE is located To execute the model with the project file the following would be entered uh sample lis In this example the input files would be read from the inputs subdirectory and the output files would be created in the output subdirectory In general the project file contains all of the keywords which are Inputs Outputs inp inputs for the source area for UH irn rainfall hyetograph input for vfsmod iro runoff hydrograph from the source area input for vfsmod isd sediment properties for the sediment filtration submodel out summary of the inputs and outputs from UH hyt detailed summary of of MUSLE calculations and the runoff hydrograph Part II VFSMOD and UH User s Manual 58 All inputs for UH are in FORTRAN77 free format The inputs are contained in filename inp Note that filename could and should be replaced by any other name you would like to identify the case study with max 8 characters as in the example above A description of this file follows 2 3 UH input files 2 3 1 filename inp parameters for generating inputs for VFSMOD 2 3 1 1 Structure of the file P CN A storm type D L Y blank line soiltype K C P ieroty 2 3 1 2 Definition P amount of storm precipatation in mm CN NRCS SCS Curve Number for the source area see Appendix 3 A Area
132. rologic soil group Hydrologic Cover Type Condition A B C D Poor 68 79 86 89 Pasture grassland or range continu E Fair 49 69 79 84 ous forage for grazing Good 39 6l 74 80 Meadow continuous grass pro 30 58 71 78 tected from grazing and generally mowed for hay Brush brush weed grass mixture For 48 67 A p with brush the major element Fair 35 56 70 T Good 39 48 65 73 Woods grass combination orchard Poor 57 73 82 86 or tree farm 4 Fair 43 65 76 82 Good 32 58 72 79 Poor 45 66 77 83 Woods Fair 36 60 73 79 Good d30 55 70 77 Farmsteads buildings lanes drive 59 74 82 86 ways and surrounding lots a Poor lt 50 ground cover or heavily grazed with no mulch Fair 50 to 75 ground cover and not heavily grazed Good 75 ground cover and lightly or only occasionally grazed b Poor lt 50 ground cover Fair 50 to 75 ground cover Good gt 75 ground cover c Actual curve number is less than 30 use CN 30 for runoff computations d CN s shown were computed for areas with 50 woods and 50 grass pasture cover Other combinations of conditions may be computed from the CN s for woods and pasture e Poor Forest litter small trees and brush are destroyed by heavy grazing or regular burning Fair Woods are grazed but not burned and some forest litter covers the soil Good Woods are protected from grazing and litter and brush adequately cover the soil 1 Average runoff condition
133. rryover from prior corn crop p See table E 9 q Use values from lines 33 62 with appropriate dates and lengths of cropstage periods for beans in the locality r Values in lines 109 122 are best available estimates but planting dates and lengths of cropstages may differ s When meadow is seeded with the grain its effect will be reflected through higher percentages of cover in cropstages 3 and 4 t Ratio depends on percent cover See table E 9 Part IV VFSMOD Appendices 124 u See item 12 table E 8 3 6 Contour factor P values for MUSLE equation in UH Contour factors P Factor from Wischmeier and Smith 1978 Land Slope Contour Factor Maximum Length 70 ft m 1 2 0 6 400 122 3 5 0 5 300 91 6 8 0 5 200 61 9 12 0 6 120 36 13 16 0 7 80 24 17 20 0 8 60 18 21 25 0 9 50 15 3 7 References for Soils and Vegetation data References for the above Tables are Knisel Walter G F M Davis R A Leonard 1992 GLEAMS Version 210 Users Man ual Pre Publication Copy US Department of Agriculture Agricultural Research Ser vice Available from University of Georgia Coastal Plain Experiment Station Bio and Ag Engineering Tifton GA UGA CPES BAED Publication No 5 259 pp McCuen R H W J Rawls and D L Brakensiek 1981 Statistical Analysis of the Brooks and Corey and the Green Ampt parameters across soil textures Water Resour Res 17 4 1005 10
134. rt Row above Delete Current Plot Hyetograph Current Row Row Save Continue Editing Save and Close Close Help NRAIN integer number of rainfall periods including period to end simulation Part III VFSMOD W User s Manual 79 RPEAK maximum rainfall intensity for the storm m s time s and rainfall rate o intensity m s over the VFS for each period RAIN I J The last time step corresponds with the desired simulation time chosen by the user typically coupled with a rainfall intensity of 0 Note also that each time corresponds to the beginning of the rainfall period The hyetograph can be viewed by selecting the Plot Hyetograph button nlx 21 417 17 1336 12 8502 8 5668 Rainfall m 3 10 65 4 2834 0 13 211 26 422 39 633 52 844 66 055 Time min Copy Plotto Clipboard Print Plot Edit Plot 5 6 VFS Source Area Storm Runoff iro The runoff hydrographs from the source area can be manually entered or generated using the UH program See the UH program documentation for further information Part III VFSMOD W User s Manual 80 x vfsm Editing E vfsmod w combo2 testgui inputs sample2uro Storm Runoff Hydrograph iro nputs sample2 ira Number of time steps of the incorning hydrograph 53 RO m 3 s 9875 84 0 Source Area Width 00 0 10108 4 00189748 SWIDTH m 10341 0177545 10573 6 0561589 Source area flow path fi 00 0 10806 2 113942 length S
135. s If the user would like to also do the analysis for the VFSMOD parameters they can switch to the VFSMOD screen Part III VFSMOD W User s Manual 86 at vFSmod Paramater Selection VFS Sensitivity Parameter Selections Base Project Files Parameters Iv pid Ampt Ksat VKS cm h E Green Ampt Theta Initial cm 3 cm 3 Dp Particle Class Diameter cm Vv Media Element Spacing 8S cm Do Simulations Base Values Min Values SetUH Parameters samplel prj Max Values Increment Load Different Base Project Cancel Help ARE Similar to the UH screen only selected parameters are available for sensitivity analysis Currently the parameters are the saturated vertical conductivity and initial water content for the Green Ampt infiltration submodel for the filter strip and the Dp Particle Class diameter and SS Media Element Spacing parameters Selection of each parameter is done with the Check boxes and setting minimum and maximum values along with an increment for the sensitivity analysis Once the simulations are complete the user can do some analysis using the VFSMOD Selected storm outputs are saved in files for each parameter selected For example if Curve Numbers are selected then the suggested name for the output of the sensitivity parameters is UHCNsens sen PERIZIA iE File Edt Block Convert Options view Help Bn amp r mQororxEmSYxx5 6
136. s of the US Type III is used for storms along the Gulf coast southern Florida and coastal areas of the eastern US Soil Erodibility Factor K This is the USLE soil erodibility factor If K 0 then K is computed based on texture and organic matter See Universal Soil Loss Equation USLE on page 21 C Factor The USLE Crop factor See MUSLE Crop factor C on page 119 P Factor The USLE P Practice factor See Contour factor P values for MUSLE equation in UH on page 125 Soil Type for the surface soil layer See Definition on page 59 dp Particle Class Diameter ranges from 15 to 200 um Tables based on soil types are used when the user specifies 1 See Tips for running the model on page 50 Rainfall Factor The rainfall factor for the modified storm version of USLE Select the method to compute the storm R factor in MUSLE not present or 1 selects Foster s Method 2 selects Williams method and 3 selects the CREAMS GLEAMS method The User can change the name of the input file in the Input Filename window The inputs can be saved using the Save button In this case the window remains open for further editing This is helpful to create multiple inputs The Close and Save will save the inputs and close this window The Help button gives this help screen Part III VFSMOD W User s Manual 73 5 VFS Project Window V vfsm Project sample1 prj ws n x Working Directory E vism
137. s package can be used to comprehensively evaluate and develop designs for vegetative filter strips to trap sediment and enhance infiltration A typical application of the package would follow the outline below 1 2 3 4 5 6 Develop input datasets for UH to generate storm data for a typical upslope source area Run UH to develop input hydrograph and hyetograph data for VFSMOD Develop input datasets for VFSMOD for describing the filter strip Run VFSMOD to simulate the performance Modify any of the inputs for UH and or VFSMOD to better reflect target source area filter strip Use the Design Option to examine a range of storm events filter strip combinations to evaluate alternate possible designs After Step 5 or 6 an alternate path could examine the uncertainty associated with the proposed design Following this path the user can use the Sensitivity and Uncertainty Options to investigate The steps would be 1 2 3 4 Use the Sensitivity options to identify the most sensitive parameters for the design centered on the base input values for the target source area and filter strip Select the most sensitive parameters and assign these probability distributions Use the Uncertainty section to perform Monte Carlo Simulations Using the Analysis portion of the Uncertainty Section examine the probability distributions for the key outputs of interest and assign confidence intervals and other estimates on
138. sand 84 8 0 01624 0 0325 0 025 135 0 Loamy coarse 84 8 0 00982 0 0325 0 025 180 0 sand Very fine sand 90 5 0 04401 0 0325 0 050 140 0 Fine sand 90 5 0 02173 0 0000 0 050 160 0 Sand 90 5 0 01481 0 0325 0 050 170 0 Coarse sand 90 5 0 00827 0 0325 0 050 200 0 3 3 2 Modifications to USLE to handle storm events USLE was developed for extended periods for example yearly To attempt to use USLE for storm events others have modified EI to represent a storm event and used this in place of R in the original equation Williams 1975 The erosion index EI is a measure of total raindrop energy of a storm One approach for computing EI is to examine 30 min rainfall intensities and compute erosion indices for these periods referred to as El3 In this approach one sums EI over each rainfall period to obtain a rainfall erosivity factor for the Part I VFSMOD W Model Documentation 23 storm In the CREAMS model Cooley 1980 used e 916 331log i 30 where e is the energy in ft ton acre in 1 ft ton acre in 26 38 J m or 26 38 N m i is the hourly intensity in in h in h 0 007 mm s and log is base 10 The E X e r over the storm where r was the increment of rainfall during the rainfall period In this situation the product of E and the maximum 30 min rainfall intensity 155 divided by 100 is used as the erosivity factor R in the USLE for the particular storm Multiplication of this by 1 7
139. selected as nodal values for the finite element grid in zones A t and B t whereas C t and D t remain unchanged Figure 3 Changes in surface saturated hydraulic conductivity values K are considered negligible The new surface parameters are fed back into the hydrology model for the next time step Surface changes are Part I VFSMOD W Model Documentation 8 accounted for in this way The time step for the simulation is selected by the kinematic wave model to satisfy convergence and computational criteria of the FE method based on model inputs Mufioz Carpena et al 1993a b At the end of the simulation the model outputs include information on the water balance volume of rainfall field inflow filter outflow and infiltration hydrograph sediment balance field inflow filter outflow and deposition sedimentograph filter trapping efficiency and sediment deposition pattern within the filter 2 4 Solution procedure The VFSMOD main program calls the subroutines along the solution procedure The backbone of the model is the numerical solution to the overland flow equation and the infiltration and sediment transport models are called upon to solve the equation for each time step at the time of assembling the matrix system The numerical method is based on a N 2 upwinding Petrov Galerkin finite element method approximation for the spacial derivatives and a time weighting finite difference approximation for the time derivatives
140. ses involved for a given scenario Results from this model can be used after calibration and field testing in extrapolation or prediction studies for decision making and design Suwandono et al 1999 Mu oz Carpena and Parsons 2002 Parsons and Mufioz Carpena 2002 An evaluation of the model from the user s perspective following modern criteria can be found in Mu oz Carpena and Parsons 1999 The GUI and integrated design procedures introduced with v2 x and above are intended to help extend the model user base to include others like engineers and environmental and natural resources experts involved in the design implementation and evaluation of VFS without requiring in depth computer knowledge Part I VFSMOD W Model Documentation 32 7 Known Limitations and Applicability of the Models 7 1 Known Limitations of the Model The handling of overland flow as sheet flow could pose problems when a filter is not properly maintained and concentrated flow occurs within the filter Since parameters to describe hydrology and sediment transport in VFS are highly variable field variability is an inherent source of error A range of variation in the saturated conductivity parameters is usually needed to fit the model to observed data Although this variation can be explained by changes in surface conditions due to seasonal and biological factors these changes are difficult to quantify in field situations 7 2 Future Research A
141. simplified to K TF 12 0 OM SF PF 28 where K soil erodibility factor in tons acre EI TF texture factor OM percentage organic matter SF structure factor PF permeability factor TF SF and PF are given in the following Table for the primary soil types K is converted to SI units kg N h m by multiplying by 0 1317 So K in SI units kg Part I VFSMOD W Model Documentation 22 N h m is given by K 03I7 TF 12 0 OM SF PF 29 TABLE 1 Factors for computing K by soil type from GLEAMS based on data from Wischmeier et al 1971 Soil Type Sand Silt Texture Structure Permeability D50 DA A Factor Factor Factor Clay 20 30 0 01287 0 0650 0 075 23 0 Silty clay 10 45 0 01870 0 0650 0 075 24 0 Sandy Clay 50 10 0 01714 0 0650 0 075 66 0 Silty clay loam 15 50 0 02606 0 0650 0 050 25 0 Clay loam 35 30 0 02360 0 0650 0 050 18 0 Sandy clay loam 55 20 0 02778 0 0650 0 050 91 0 Silt 5 85 0 05845 0 0650 0 025 19 0 Silt loam 20 60 0 04259 0 0650 0 025 27 0 Loam 45 35 0 03618 0 0325 0 025 35 0 Very fine sandy 60 25 0 03877 0 0350 0 000 35 0 loam Fine sandy loam 60 25 0 03205 0 0000 0 000 80 0 Sandy loam 60 25 0 02549 0 0325 0 000 98 0 Coarse sandy 60 25 0 01914 0 0325 0 000 160 0 loam Loamy very fine 84 8 0 03726 0 0325 0 025 90 0 sand Loamy fine sand 84 8 0 02301 0 0000 0 025 120 0 Loamy
142. solves the kinetic wave approximation of the Saint Vennant s 1881 equations for overland flow KW for the 1 D case as presented by Lighthill and Whitham 1955 such as Oh Og i t Continuity equation 1 Ot Ox S S Momentum equation oO Then a uniform flow equation equation can be used as a link between the q and h such as Manning s 5 5 13 q q h Bo 2 Where A is depth of overland flow L q is the flow per unit width of the plane eT So is the slope of the plane Sy is the hydraulic or friction slope and n is Manning s roughness coefficient fe 3 The initial and boundary conditions can be summarized as 0 0 lt x lt L t 0 3 Hox h lt h 0 t gt 0 Il x where h can be 0 a constant or a time dependent function such as the incoming hydrograph from the adjacent field This could also be a linkage to other water quality models describing the runoff source area The rainfall excess ie is calculated from the hyetograph and a modification to the Green Ampt infiltration method at every time step Mu oz Carpena et al 1993 The overland flow model was coupled for each time step with an infiltration submodel based on a modification of the Green Ampt equation for unsteady rainfall Chu 1978 Mein and Larson 1971 1973 Skaggs and Khaheel 1982 Mu oz Carpena et al 1993b Part I VFSMOD W Model Documentation 4 PEt 4 p K t 1 1 F MS In 1 E 5 av where f
143. t oo D p P b Nb PN rt Sta End Inc Design Storm Range rnm 20 rm 100 mm 10 Design Storm Specific values Lower Upper Increment Base V VFS Length m Um pa P e 655 v Grass Veg Media Spacing cm p2 fs for p2 Deisgn Results Filename DesignRescsv OK Run Cancel Help During the design procedure UH and VFSMOD are coupled automatically to explore the user selected range of factors included in the design The programs execute as follows 1 For each step design factor combination VFSMOD W creates a design lis combining inputs from the UH base project and a design storm 2 Executes UH with the newly created design lis and produces the VFSMOD files design iro design irn design isd and design iso 3 Creates the remaining design igr and design ikw combining inputs from the VFSMOD base project and a design filter length vegetation spacing value 4 Creates a VFSMOD design prj file using the files above and Executes the VFSM 5 Loops back to 1 until all simulations are completed Currently there are no options for the Design Analysis section The output file from the design analysis simulations can easily be imported into a spreadsheet for further analysis The file format is comma separated variable csv Part III VFSMOD W User s Manual 95 File Edit Block Convert Options View Hep OR Gy a Glo oy t BY ws lat E Y DesignRes test csv besign Par
144. ter Two possible methods were presented for generating the general probability distributions of the output variables of interest Haan et al 1995 and Haan et al 1998 The first method was First Order Approximation FOA Morgan and Henrion 1990 In this method the mean or expected value of the output is estimated as E O Model P 37 and the variance is estimated as R reo 6080 Var O Ib Va P 2y Y Gap Cos P 38 i21 i lj itl where O is the output parameter of interest Pj is the base input parameter values for the Part I VFSMOD W Model Documentation 28 selected input variable P is the input parameter i n is the number of input parameters Var is the variance and Cov is the covariance If the input parameters are independent and uncorrelated an assumption that is often made then the second term is 0 ie Cov P Pj 0 The slope of the sensitivity relationship between O and P is S With these assumptions the variance equation becomes Var 0 Y S Var P 39 i This type of analysis produces good estimates of the mean and variance of the output parameter O when the coefficient of variation Mean Standard Deviation of the input parameter is small and the relationship between O and P over the range of potential inputs is linear An alternative more general approach is the technique of Monte Carlo Simulations MCS An outline of this procedure is 1 select the most sensitive input pa
145. ters The model developers encorage the users to obtain the soil inputs for the model based on sail samples taken on site If that is not possible or the model is applied to study the effect of soil type on the effectiveness of the VFS the following table gives values for the Green Ampt parameters as suggested by Rawls and Brakensiek 1983 3 3 3 Soil Texture USDA K m s x10 S m Porosity x 0 m m Clay 0 167 0 0639 1 565 0 427 0 523 0 3163 0 475 Sandy clay 0 333 0 0408 1 402 0 370 0 490 0 2390 0 430 Clay Loam 0 556 0 0479 0 9110 0 409 0 519 0 2088 0 464 Silty Clay 0 278 0 0613 1 394 0 425 0 533 0 2922 0 479 Silty clay loam 0 556 0 0567 1 315 0 418 0 524 0 2730 0 471 Sandy clay loam 0 833 0 0442 1 080 0 332 0 464 0 2185 0 398 Loam 3 67 0 0133 0 5938 0 375 0 551 0 0889 0 463 Silt loam 1 89 0 0292 0 9539 0 420 0 582 0 1668 0 501 Sandy loam 6 06 0 0267 0 4547 0 351 0 555 0 1101 0 453 Loamy sand 16 6 0 0135 0 2794 0 363 0 506 0 0613 0 437 Sand 65 4 0 0097 0 2536 0 374 0 500 0 0495 0 437 Note Values in parenthesis are mean values For an alternative source of Green Ampt soil parameters see also McCuen et al 1981 3 2 Manning s roughness coeficient n There are several publications dedicated to the stimation of this important parameter for overland flow routing see Arcement et al 1989 A summary of the most common values use
146. that the effective rainfall fed into the kine matic wave equation ie will be in most cases a negative value The procedure is as follows a check if the end of runoff has been reached b check for surface ponding at beginning yes NPOND 1 no NPOND 0 b 1 without surface ponding at the beginning of the period NPOND 0 b 1 1 with ponding at the end of the period Cu gt 0 b 1 2 no ponding at the end of the period Cu lt 0 b 1 3 Find values at the limit of this rainfall period regardless of time step b 2 with surface ponding at the beginning of the period NPOND 1 c return ie value to be used in that time step 1 14 FORMB B0 X0 Q0 N BCRO PGPAR In this subroutine the right hand side part of the matrix equation vector b is assembled in the following steps a find dx1 for integration rule b initialize vector bj c begin vector formation element by element c 1 Initialize temporary vectors c 2 do integration point loop c 3 plug the element vector into the b0 vector d Plug in the boundary condition b 1 BCRO Part IV VFSMOD Appendices 102 1 15 MODIFY QM B BCRO PGPAR In this subroutine the right hand side part of the equation vector b is assembled follow ing the procedure discussed by Vieux et al 1990 a find dx for integration rule b begin vector formation element by element b 1 do integration point loop b 2 plug the element vector into the b vector c plug in the boundary conditio
147. the final filter strip designs note the program supplies basic statistics and the actual simulated data to allow the users to use other outside analysis tools to complete this analysis users are welcome to contact us for suggestions Part III VFSMOD W User s Manual 68 3 Main Window EM vrSmod Windows Editor v 2 2 2 E File Source Area UH Filter Strip VFS Design Sensitivity Uncertainty Options Window Help Application of VFSMOD is done via project files The project files consist of a list of filenames identified by keywords indicating the type of input or output file To Open a project file select the File Menu and Open a VFS Project File s Eus Windows Editor v 2 2 2 HE Source Area UH Fiter Strip VFS Design Sensitivity Uncerte o Current Filter Strip LI Batch of Filter Strip cum Open Execution Panel From the main window you can also execute VFSMOD This option is available from the VFSM menu This menu contains submenus for Execution and Analysis Under the Execution submenu the current project a project from disk or multiple projects from disk can be executed The Analysis submenu can be used to view output files from VFSMOD in addition to graphing and comparing some of the outputs generated by VFSMOD Part III VFSMOD W User s Manual 69 Other menu selections include Design Sensitivity and Uncertainty These are discussed in more details in other sections 3 1 vfsmod w Options
148. till 1 2 ton hay 107 40 cover till strips 4 4 4 4 4 4 4 108 20 cover till strips 5 gt 5 2 5 5 5 Other tillage after sod n CORN after Soybeans 109 Sprg TP conv till HP 40 72 60 48 25 29 110 GP 47 78 65 51 30 25 37 111 FP 56 83 70 54 40 31 26 44 112 Fall TP conv till HP 47 75 60 48 25 113 GP 53 81 65 51 30 25 114 FP 62 86 70 54 40 31 26 115 Fall amp Sprg chisel or cult HP 309 40 35 29 23 29 116 GP 25 45 39 33 27 23 37 117 GP 20 51 44 39 34 27 23 37 118 FP 15 58 51 44 36 28 23 44 119 LP 10 67 59 48 36 28 23 54 120 No till pl in crop resid HP 40 25 20 19 14 11 26 121 GP 30 33 29 25 22 18 14 33 122 FP 20 44 38 32 27 23 18 40 Part IV VFSMOD Appendices 122 Spring Cover Soil loss ratio for cropstage period and canopy cover Cover Crop Sequence Resi After No and manmagement due Plant F SB 1 2 3 80 90 96 4Lf LB BEANS after Corn 123 Sprng Tp Rdl conv till HP 33 60 52 38 20 17 p 124 GP 39 64 53 41 21 18 125 FP 45 68 60 43 29 22 126 Fall Tp Rdl conv till HP 45 69 57 38 20 17 127 GP 52 73 61 41 21 18 128 FP 59 77 65 43 29 22 Chisel or fld cult q Beans after Beans r GRAIN after C G GS COTS 129 In disked residues 4500 70
149. tions add incoming and outgoing mass to totals and RETURN to main program b calculate the hydraulic properties at points 1 2 3 the filter to be used later on subroutine OCF c solve Einstein s bed load transport equation to find the transport capacity g 2 at the end of B t subroutine EINSTEIN d calculate shape of sediment wedge sediment outflow and trapping efficiency for the filter subroutine STEP3 e position points 1 2 3 at system nodes so that flow rates can be read at those points at next time step subroutine POINTS f write outputs of sediment transport calculations 1 21 OCF NPLACE This subroutine solves the hydraulic properties for each of the filter s singular points by using Manning s equation and open channel flow theory It utilizes the method proposed by Barfield et al 1979 where the known values are S spacing of the filter media ele ments cm S filter main slope n Manning s for cylindrical media s cm q unit overland flow rate at the given point k cm s and the unknowns are d depth of flow at D t cm V depth averaged velocity at D t cm s R hydraulic radius of the filter cm Notice that all units are in CGS system cm g s including Manning s n The follow ing steps are followed a flow depth and velocity set to zero for no flow at any given point b otherwise calculate R V and dy for the given point c the resulting equation is solved by the Ne
150. tory without overwriting previous results 1 4 1 filename ikw parameters for the overland flow solution 1 4 1 1 Structure of the file LABEL FWIDTH VL N THETAW CR MAXITER NPOL IELOUT KPG NPROP SX IPROP RNA IPROP SOA IPROP IPROP 1 NPROP 1 4 1 2 Definition LABEL a label max 50 characters to identify the program run FWIDTH width of the strip m VL length of the filter strip m N number of nodes in the domain integer must be an odd number for a quadratic finite element solution but the program checks and corrects if needed THETAW time weight factor for the Crank Nicholson solution 0 5 recommended CR Courant number for the calculation of time step from 0 5 0 8 recommended See Section 6 for more details MAXITER integer maximum number of iterations alowed in the Picard loop NPOL integer number of nodal points over each element polynomial degree 1 IELOUT integer flag to output elemental information 1 or not 0 KPG integer flag to choose the Petrov Galerkin solution 1 or regular finite element 0 NPROP integer number of segments with different surface properties slope or roughness SX I real X distance from the beginning on the filter in which the segment of uniform surface properties ends m Part II VFSMOD and UH User s Manual 44 RNA I Manning s roughness for each segment s m 3 SOA I slope at each segment unit fraction i e no units 1 4 1 3 File example U
151. tputs files sample ohy and sample osm The hydrographs included in the next figure show the volume reduction infiltration and peak delay increase of roughness by vegetated surface produced by the filter over the incoming field hydrograph input Part II VFSMOD and UH User s Manual 53 0 003 5 108 10 106 1 5410 2 10 EE Rainfall 2 5410 Inflow o o o Dy Outflow Flow rate m s Rainfall m s 0 001 0 1000 2000 3000 Time s The water balance for the simulation was as follows Ww Volume from rainfall 0 8423 m Volume from up field hydrograph 1 3240 m Volume from outflow hydrograph 0 7674 m Volume infiltrated 1 3990 m 1 7 2 3 Sediment transport files sample ig1 sample ig2 and sample osm The sedimentograph and mass balance at the filter is included in the next two figures Both graphs show a significant load reduction due to deposition at the wedge difference in loads between g and g 2 for those parts of the event when flow was low beginning Part II VFSMOD and UH User s Manual 54 and tail whereas most of the sediment in the suspended sediment zone was retained at high flow rates when the sediment by passes the wedge 0 2 e 0 15 5 1000 2000 3000 o S9 S 0 1 t oO E Oo 3 0 05 0 0 500 1000 1500 2000 2500 3000 3500 Time s a 100 incoming E o lower area oO 80 c 9 2 60 E o 40 E 9 o 20 0 1000 1500 2000 2500 Time
152. transform into depth m at the first node of system incoming hydrograph for each time step h 2 get effective rainfall and control execution of overland flow for an infiltrating surface by calling Green Ampt model The assumption is that when a certain node NCHK is flooded i e X NCHK gt 0 all the surface will be flooded and thus the maximum infiltration capacity for the rest of the event is selected as given by the Green Ampt model NCHK is selected by the user h 3 form of r h s vector for that time step h 4 start Picard iteration h 4 1 update b b h 4 2 feed the vector to the solver h 4 3 check for convergence h 4 4 update X X h 4 5 find flow component at iteration step h 4 6 Picard iteration converges proceed with time step otherwise repeat h 6 update h and q for next time level h 7 do the following only 100 times each time using the average flow of the last NWRITE values in between h 7 1 call sediment transport subroutine if there is inflow change units from Q m s to QSED cm s h 7 1 write outputs to files h 8 repeat time loop for next time step until the end of the run 1 write a summary of results at the end of the run j close files and end program Part IV VFSMOD Appendices 99 1 2 FINPUT LISFIL This subroutine writes the program banner reads the name of the file set to be processed from the command line string creates I O file names accordingly and opens I O files
153. wton Raphson iterative method 1 22 EINSTEIN GS2 NTRCAP COARSE This program solves Einstein s bed load transport equation to find the sediment transport capacity g at the end of C t by following the method proposed by Barfield et al 1979 where known values are d particle size diameter cm S filter main slope R hydraulic radius of the filter at D t cm g g water and sediment weight density g cm g acceleration due to gravity 980 cm s COARSE of particles from incoming sediment with diameter gt 0 0037 cm i e coarse fraction that will be routed through Part IV VFSMOD Appendices 104 wedge and the unknown is g gt 2 4 sediment transport capacity or sediment load enter ing downstream section g s cm Notice that all units in CGS system cm g s The fol lowing steps are implemented a check if the transport capacity is lower than concentration a 1 if lower deposition at the wedge occurs first part of subroutine STEP3 a 2 if higher there is enough energy to transport sediment through the wedge and no deposition occurs all sediment is transported to the suspended sediment zone zones C t and D t 2nd part of subroutine STEP3 1 23 STEP3 GS2 TIME NTRCAP COARSE This program solves STEP3 of the sediment transport problem after Barfield et al 1979 and Hayes et al 1984 The outputs from this part of the problem are f sediment fraction trapped in the deposition wedge X t Y t X t

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