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MIKE FLOOD - HydroAsia

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1. 0 00000000 eee ee 62 6 7 Urbanlinks e ae d R ee 63 SCIENTIFIC BACKGROUND 0 65 7 1 Hydrodynamics Standard Links 0 o 65 Rectangular grid oo ooo o 65 MIKE FLOOD User Manual Flexible mesh 0 2 000002 eee eee 66 7 2 Hydrodynamics Lateral Links 0 0 0 66 Rectangular Grid oud ou ga e ere c ee aS 66 7 2 1 Automated cell selection 0 0 69 7 2 2 Definition of lateral linkage lines 70 7 3 Hydrodynamics Structure Links 0 71 7 3 1 Hydrodynamics Exponential smoothing factor 73 7 4 Hydrodynamics Zero Flow Links 0 o 74 7 5 Hydrodynamics Urban links o 74 7 6 Advection DiSpersi0N e e e 75 7 7 Flow Distribution by Depth 0 o e 76 7 8 Inclusion of Friction Term in Weir Formulae 1 and 2 Honma 77 EXAMPLES 2 35 idas 644 a a aoa a e a eH ees 81 8 1 o o AI 81 8 2 LateralLimk4 0 o e e 83 0 9 Lateral Link Zee ecni er We Ee ee a a a VE a a 90 8 4 Flow Direction 0 0000 e 93 8 5 Flood plain Flow aaa o 97 8 6 Floodplain Demonstration ooa 100 8 7 Urban examples ee 105 MIKE FLOOD User Manual MIKE FLOOD User Manual 10 MIKE FLOOD Ss 1 INTR
2. o Fight Bark Bank Level m R288 8 00 5 Chalnage 0 1100m Figure 8 5 Lateral Link Test 1 Left and Right Bank Levels Lateral flow spilling out of the river channel into the basin will be distrib uted across the length of the branch depending upon the bank levels the water level profile along the branch and the flow distribution will vary between the left and right sides of the river The MIKE FLOOD couple file is mf couple Run this simulation then inspect results using the Result Viewer in MIKE ZERO Contours of water depth and vectors of velocity at two instances in the simulation are shown below 1600 r Graphical Items 1600 Color point X Width point 1500 1500 1400 1400 1300 1300 1200 1200 1100 1100 1000 1000 900 o 800 800 700 700 600 600 eno H Water Depth m fm 500 Above 0 6337 0 5956 0 6337 2 0 5574 0 5956 400 0 5193 0 5574 0 4812 0 5193 0 4431 0 4812 30 0 4049 0 4431 0 3663 0 4049 as 0 3287 0 3668 200 0 2906 0 3287 0 2524 0 2906 sas 0 2143 0 2524 100 0 1762 0 2143 0 1381 0 1762 y 0 099968 0 1381 0 Below 0 09996 LJ Undefined Value 0 200 400 600 0 200 400 600 01 01 03 01 20 00 Time step 8 of 100 01 01 03 16 40 00 Time steo 100 of 100 Figure 8 6 Lateral Link Test 1 Results Water Depth and Velocity MIKE FLOOD User Manual 85 1 Examples There is a distinct difference in flow patterns between the left and right basins Using M
3. lated as normal MIKE 21 cells This is a reasonable practice the upwind ing facility automatically implemented in MIKE 21 has been shown to simulate weir flow well In this situation the weir structure in MIKE 11 would not be required and the culvert structure flows would be added to the MIKE 21 cells Note the add replace options mean that the order in which structure links are listed in the couple file will affect the model behaviour By specifying Replace in a link all previous link inflows from previous links will be overridden Also note that MIKE 11 can handle composite structures e g a culvert and a weir at the same location This may be used to handle a com plex situation with flow both over topping and flowing under an embank ment The definition of such a structure is handled in MIKE 11 and does not require two explicit couplings in the MIKE FLOOD interface MIKE FLOOD User Manual 39 asker Application details 3 3 4 Depth Adjustment If depth adjustment is active flow through a link is distributed into the MIKE 21 cells according to the water depth in those MIKE 21 cells This is considered appropriate for links on natural terrain or channels but may not always be applicable for structures 3 3 5 Activation Depth Minimum and Maximum The activation depth is valid only for the zero flow XFLOW 0 and YFLOW 0 links If specified then these links will be turned off once the activation depth is reached A m
4. 3 4 1 Side of River Side of river defines whether the lateral link is a link on the left bank or the right bank of the river channel e Left bank is equivalent to Marker 1 in the MIKE 11 cross section edi tor MIKE FLOOD User Manual 41 1 Application details e Right bank is equivalent to Marker 3 in the MIKE 11 cross section edi tor 3 4 2 Method The structure method defines the method by which flow is distributed between MIKE 11 and MIKE 21 e The CELLTOCELL method performs a flow calculation for each indi vidual point in the defined structure Each calculated flow is then redis tributed to MIKE 21 and MIKE 11 This means that the number of MIKE 11 points doesn t necessarily have to match the number of MIKE 21 cells e The SIMPLE method performs a single calculation of flow then dis tributes that flow to each MIKE 21 cell and or MIKE 11 computation h point The CelltoCell method is the default and is the only one available if link ing with a flexible mesh 34 3 Structure Type The structure type defines the type of flow calculation to be performed e WEIRI MIKE 11 Weir Formula 1 with friction term included e WEIR2H MIKE 11 Weir Formula 2 Honma with friction term included e OHTABLE A QH table is used read in from an external file Note that if using a CELLTOCELL method the Q in the QH table is the flow per unit width e ODTABLE A QH table is used except that water depth above the structur
5. A cross sectional area K linear decay C the source sink concentration and q lateral inflow per river length For zero flow links no advection will occur across the link due to the zero flow specification and dispersion is turned off 7 7 Flow Distribution by Depth Flow is distributed according to the Chezy equation for resistance Q ACARS 7 25 where Q Flow A Area width depth w h C Chezy coefficient 76 MIKE FLOOD Inclusion of Friction Term in Weir Formulae 1 and 2 Honma R Hydraulic radius approx depth 4 and S slope Rearranging this equation gives Q whch s h wcs 7 26 Thus proportionality can be derived between flow and water depth A CuK 7 27 Flow is then distributed across a number n of MIKE 21 cells For each cell count 7 1 n the distributed flow O is calculated from the total flow Oror h Q Qror y 7 28 7 8 Inclusion of Friction Term in Weir Formulae 1 and 2 Honma The equation for the Weir Formula 1 is 7 i h 70 385 Gz wCni I 7 29 where w width C weir coefficient 1 838 m s k exponential coef ficient 1 5 4 depth of water above weir level upstream Hs H and hy depth of water above weir level downstream Hgs H This equation is actually a free overflow term wCh combined with a scaling term for submergence 385 that approaches 0 as A approaches h The equa tion for th
6. MIKE FLOOD User Manual 11 Si Introduction 1 1 General Approach to Modelling with MIKE FLOOD Consider the modelling systems that are integrated MIKE 11 MOUSE and MIKE 21 By combining the systems the modeller can choose the best features of each and make the best model with these features For instance consider the following abilities and limitations of MIKE 11 Has comprehensive and proven structure routines Can model very long or complicated river systems with little computa tional effort Can model one dimensional channel flow accurately Can be easily linked to rainfall and runoff programs Can simulate high velocity super critical flow conditions Is one dimensional so two dimensional effects such as cross channel momentum is not possible Overland flow is difficult to model if flow paths are uncertain Requires more conceptualisation of flow conditions and more approxi mations Cannot easily simulate a coastal situation Consider then MOUSE Has sophisticated descriptions for pipe flow and structures Can model highly complex pipe networks Can be easily linked to rainfall and runoff programs May be used to model open sections Is one dimensional so a true two dimensional description of the over land flow is not possible Difficult to describe the complex interaction between overland flow and pipe flow Finally consider MIKE 21 Two dimensional means more accuracy and better resolution 12 MIKE
7. MOUSE or MIKE URBAN It is important to look at weirs and pumps in the system and find out if they should be coupled to the MIKE 21 model in such a way that the water flows naturally Flow from weirs in MOUSE is one directional i e the flow only flows into the MIKE 21 model and not back into the MOUSE model This can be fixed if needed by adding a small pipe and an outlet to the MOUSE model and couple in the outlet instead MOUSE will automatically allow MIKE 21 to change the ground lev els in manholes if the change is within an acceptable limit The limit may be set in the DHIapp ini file MM21 ALLOWEDGROUNDLEVELDIFFERENCE It is in gen eral recommended to ensure that manhole levels correspond to the topography It is important to consider the artificial basins on top of manholes in MOUSE i e the reservoir height above ground The reservoir height is the distance from the manhole ground level to where the expansion for ponding starts 25 cm below the man hole level is the default value but when coupling MOUSE with MIKE FLOOD this should be increased to e g 100 m above Make sure the FLOODLIMIT parameter does not conflict with the reservoir height MIKE FLOOD User Manual 57 Ss Tips and troubleshooting 6 2 Stability MIKE 11 The MIKE 11 MOUSE MIKE URBAN and MIKE 21 manuals con tain information on stability in numerical modelling The comments made are equally applicable for MIKE FLOOD Most issues relat
8. The set up files are located in the folder DHI MIKEZero examples MIKE FLOOD Urban The example mimics a storm event that results in the sewer system being surcharged causing inundation in the streets 1520000 1519500 1519000 1518500 1518000 1517500 1517000 1516500 1516000 1515500 668000 670000 672000 674000 Figure 8 33 The grid with the sewer system shown in pink MIKE FLOOD User Manual 105 y Examples 106 MIKE FLOOD INDEX 107 Ss Index A R Activation Depth 40 Result Viewer 52 Add Remove Images 32 river name 24 Add Remove Layers 29 Add Replace Momentum Terms 39 S Advection Dispersion 56 Scientific Background 65 Side of River 41 Cc Smagorinsky Eddy Viscosity 56 Coupling Type 23 Stability ewe a wee ee aa 58 Standard Links 15 59 D Standard Structure Links 38 Default Value for Land 56 Structure 42 44 DELTA parameter 55 58 Structure Links 16 61 Depth Adjustment 40 Depth Tolerance 43 T Tips and Troubleshooting 55 E Explicit Links 58 Z Ext Fact 38 Zero Flow 18 24 62 External Files 44 G Graphical View 26 H Hydrodynamics 65 L Lateral Links 15 24 41 59
9. are added the flow conditions calculated in MIKE 11 are added to the flow conditions in the MIKE 21 cell 6 6 Zero Flow Links e A single link can be used to specify all XFLOW 0 cells in a MIKE 21 grid The same applies for the YFLOW 0 cells e With regard to activation depth the idea is that for most flooding con ditions there will be left bank flood plain flow in bank channel flow and right bank flood plain flow The interactions between these three will be governed by the MIKE FLOOD links However water depths could increase until the interactions between the separate flow paths are no longer relevant At this stage a MIKE 21 simulation without the MIKE FLOOD links would be more accurate By using the activation depth to switch on 2D flows across a river channel this could be done 62 MIKE FLOOD Urban links y 6 7 Urban links e Itis possible to couple to multiple cells if using a rectangular grid For the flexible mesh it is possible to couple to an area In general using multiple cells or an area as opposed to coupling to only one point will enhance stability MIKE FLOOD User Manual 63 Tips and troubleshooting 64 MIKE FLOOD Hydrodynamics Standard Links e 7 SCIENTIFIC BACKGROUND The scientific backgrounds of MIKE 11 MOUSE and MIKE 21 are also applicable for MIKE FLOOD 7 1 Hydrodynamics Standard Links Standard links are treated slightly differently depending on whether a flex
10. it assumes that nor mal bed resistance represented by a Chezy or Manning number controls the flow If a structure is present in the last O grid point in MIKE 11 a link to MIKE 21 the predictor is not used Flexible mesh For the flexible mesh the standard link is designed is such a way that the linkage line is mapped onto one or more element faces Thus from MIKE 21 s point of view the link functions as a boundary condition In return MIKE 21 transfers an average water level across the coupled element faces which is then subsequently used in MIKE 11 It is required that the whole of the coupling line is within the mesh to ensure that total discharge is transferred from the river model to the overland mesh model The predictor is not used for the flexible mesh solution I 7 2 Hydrodynamics Lateral Links For lateral links flow from the river model goes via a lateral boundary which is then applied into MIKE 21 The lateral link varies from the stand ard source sinks in the following ways 1 Flow through the link is dependent upon a structure equation and water levels in MIKE 11 and MIKE 21 2 Flow through the link is distributed into several MIKE 11 A points and several MIKE 21 cells elements 3 The lateral links do not guarantee momentum conservation The latter point is not surprising since the 1D model per definition does not consider cross channel momentum A structure is required to calculate the flow between
11. 60 Link Type 264 x oe gene aa oes 23 Linkage Types 31 M MIKEL astas Es ad A rod 21 MIKES ass ra ehh ds ewes 20 MIKE 21 Area Number 25 MIKE 21 Coordinates 25 Model Layout 49 Mom Fact 38 P Pre and Post Processing 51 Q QH table cocos rr 15 108 MIKE Flood
12. FLOOD General Approach to Modelling with MIKE FLOOD _ AS e Two dimensional so overland flow can be simulated more accurately also has efficient flooding and drying facility e Can simulate high velocity supercritical flow conditions e Can simulate a coastal situation e Requires more computational effort Additionally MIKE 21 rectangular grid has the following abilities and limitations e Nested grid option means more flexibility with resolving features e Fixed grid means less flexibility with resolving features e Can be difficult to model narrow channels and flow paths particularly if diagonal to flow e MIKE 21 boundaries must be aligned with the grid horizontal or verti cal Finally the abilities and limitations of MIKE 21 flexible mesh are the fol lowing e Adaptive time step so that the time step of the 2D part adjusts to the dynamics e Boundaries may have any alignment e The river outline may be integrated in the mesh e A fine mesh may be needed for resolving rivers and streams in mesh Consider which of these features are most desirable for your application How can you integrate MIKE 11 MOUSE and MIKE 21 to best utilise the most desirable features while minimising the bad features MIKE FLOOD enables this integration to be performed easily but it is still the modeller who decides how best to design the integrated model This man ual will help you to make the decisions on how best to create a MIKE FLOOD
13. ID fdemim Chainage upstream IF Chainage downstream aoo Figure 3 12 The link branch to MIKE 21 sub menu Note that for a lateral link two chainages are required whereas for standard structure links only information on whether the link is to be applied to the upstream or the downstream end of a branch is needed Add Remove Images This menu controls the images to be shown The following files are possi ble to display e graphical image files bmp jpg and gif e GIS shape files shp e XYZ ASCII files xyz e MIKE 11 network files nwk11 e Enhanced metafiles emf For each of the different files some of the display settings may be edited by clicking the edit button found in the same row as the image file to be edited 32 MIKE FLOOD The graphical layout e Image Manager Overlay Manager Image Files File type File name 1 Image File CAMIKEZERO dev Source ExampleMFlood FloodplainDemonstrationip OK Cancel Help Figure 3 13 The image manager Images may be added or removed using the two buttons in the upper right hand corner The second tab is identi cal to the overlay manager found in the Add Remove Layers menu shown in Figure 3 11 3 2 5 Block out river cells If the widths of the rivers in a set up are more than one cell size wide then it may be appropriate to block out the cells lying within the main river bed Hereby one ensur
14. MIKE 11 and MIKE 21 This structure is typically a weir that represents over topping of a river bank or levee The geometry of the structure can be determined from cross section bank markers MIKE 21 topographical levels a combination of the highest of each or from an external file Rectangular Grid With a CELLTOCELL method the structure geometry is subdivided into a series of internal structures Each internal structure has a bed level and a width determined from the resolution of points defined along the structure 66 MIKE FLOOD Hydrodynamics Lateral Links e Consider the schematic diagram in Figure 7 1 of a structure defined from MIKE 11 A points Extent of Lateral Link structure Ke ee ane io MA 11 Ro Structure gt a defined with a single Ae a Branch H point bed level and a width H TA Figure 7 1 Lateral Link Definition of Internal Structures The internal structures are defined so that all of the information available in the structure geometry is utilised During computation each internal structure is assigned a water level from the river and from the overland solver These values are found by interpo lating levels at existing calculation points onto the internal structures Consider the schematic diagram in Figure 7 2 of an externally defined structure where the internal structure locations differ from the MIKE 21 cell locations and the MIKE 11 h point locations As shown water levels are in
15. as a demonstration model to illustrate a real application of MIKE FLOOD The application consists of a flood simula tion through a river system The area of interest is at a confluence with a tributary where a road embankment has been proposed Culverts under the road are located on each side of the river The river system is represented in MIKE 11 A MIKE 21 grid is inserted into the broader MIKE 11 network to represent flood plain flow as shown in Figure 8 28 100 MIKE FLOOD Floodplain Demonstration _ e Downstream Water Level S Main River ent 372500 Figure 8 28 Floodplain Demonstration Layout A 5 s time step is used in the simulation and the MIKE 21 grid size is 30 m The model has been developed with the following MIKE FLOOD links e lateral links between the main river channel and floodplain and the tributary and floodplain e zero flow links along the centre line of the river channel to ensure that water flows from one side of the floodplain to the other via the main channel e similarly zero flow links along the centre line of the tributary e zero flow links defining the road embankment assuming that the road does not over top e implicit structure links for flow through the culverts A diagram illustrating the locations of the links is shown MIKE FLOOD User Manual 101 Examples XLateral Link Right Bank Lateral Link Left Bank XImplici t Structure Links Zer
16. at Add a new link The link will be augmented to the list x Remove an existing link Move an existing link up the list Ka m Move an existing link down the list MIKE FLOOD Definition LAA Please note that the insert and delete keys on the keyboard cannot be used for inserting and deleting links in the overview 3 1 5 Link Type The link type defines the type of link e Standard E the E indicates that the link is explicit e Lateral e Structure I The I indicates that the link is implicit e XFLOW 0 e YFLOW 0 e Urban The link type is set from the combo box 3 1 6 Coupling Type The coupling type can be e HD only the link will only transfer hydrodynamic information requires HD simulation defined in both linking models e AD only the link will only transfer advection dispersion information e HDand AD The coupling type is selected through the use of a combo box Note that the AD link is only possible between MIKE 11 and MIKE 21 rectangular gridand requires that the AD simulation is defined and licensed in MIKE 11 and MIKE 21 Presently the AD linking is not avail able for the Urban link MIKE FLOOD User Manual 23 y Application details 3 1 7 MIKE 11 River Name Node ID and Chainage e Ifusing a standard or structure link M11 river name is the MIKE 11 branch with the link and Ist US M11 chainage is the chainage of the MIKE 11 boundary point Note that this is not necessa
17. branch linked to a MIKE 21 basin using a standard link an my MIKE 11 Branch rT 1 7 Toy MIKE 21 Grid eno 4 i 400 300 2073 Weir Type 1 100 7 ond Standard Link 1000 am 600 400 200 o 200 400 600 an om 1200 1400 1600 1600 2000 20 Figure 8 14 Lateral Link Test 2 Standard Link Layout 90 MIKE FLOOD Lateral Link 2 LEA The MIKE 11 branch is 1000 m long with a uniform cross section of width 500 and bed level 0 m The MIKE 21 basin is also 500 m wide with a bed level of 0 m and is 1000 m long Grid spacing is 100 m The MIKE 11 branch has a weir located near the link chainage 850 m This weir has a height of 2 2 m and is 500 m wide A weir formula 1 is applied The second test aims to replicate the first except using a lateral link rather than a standard link The MIKE 11 branch branch1 is the same as the first test except it is truncated at the weir location at chainage 800 m where another branch latb is attached This branch has a length of 500 m and the left banks of the cross sections have a bed level of 2 2 m The lat eral link connects this branch to the MIKE 21 basin A weir formula is applied in the lateral link MIKE 21 Grid 700 MIKE 11 Branches M11 branch connection a 100 o Lateral Link vA 1000 200 00 400 200 0 200 400 600 800 1000 1200 400 600 1800 Figure 8 15 Lateral Link Test 2 Lateral Link Layout The initial water level and the downstream wat
18. ewes eau ew ee ee ee ae 45 Flexible Mesh cee ee 46 Generating the ASCII file with the invert levels 46 3 5 Options for Urban links 0 0 47 RAI OI 47 3 5 2 Inletmethod 0 2 000000 0000 47 303 IMaxstlOw sos o sues a cala amp Gade ee ga E Bee a 47 3 5 4 Inletarea o 48 3 5 5 Crestwidth o 48 3 5 6 Scaling factor ae de AS 48 3 5 7 Exponent factor aaa aa o 48 RUNNING MIKE FLOOD RECOMMENDED STEPS 49 4 1 Define Model Layout anaa aaa a 49 4 2 Setup and Run 1D Models naaa 49 4 3 Setup and Run MIKE 21 Model 50 44 Setup MIKE FLOOD 0 0220 50 45 Run MIKE FLOOD Simulation 50 PRE AND POST PROCESSING o o a 51 5 1 Google Earth plugin s c 4ee42 e80 ee 4d aout ads 52 TIPS AND TROUBLESHOOTING 55 6 1 General Considerations 0 2 2 55 MIRE 6 ted Rara Roh id de e do 55 MIKE 21 rectangular grid a 56 MIKE 21 flexible Mesh a 56 MOUSE or MIKE URBAN Lo 2 57 6 2 Stability co Lou ca a mr ee OR A ee 58 MIKE oasis dd ted dd OOS 58 6 3 Standard Links 20 00 0000 0000222 59 6 4 LateralLinkS 0 o e e 60 6 5 Structure Links cio ici e as 61 6 6 Zero Flow Links
19. left in for compatibility The second parameter indicates the level of debug information reported 0 for none and 1 2 or 3 for debug output If the parameter is 3 then only Courant number warnings are printed in the log file The third parameter is default 1 indicating that the same time step is used in MIKE 11 and MIKE 21 MIKE Flood my be run with a dif ferent time step in the two models The default is that the time step is carried over from MIKE 21 Thus the time step specifications in MIKE 11 are over written when running MIKE Flood If desired the time step in MIKE 11 may be chosen as a multiple of the time step in MIKE 21 The third parameter after the M21_Run_Info keyword specifies the time step multiplication factor used in MIKE 11 MIKE FLOOD User Manual 55 Tips and troubleshooting The last parameter is used to scale advection dispersion results default 1 0 Incoming MIKE 11 AD concentrations are divided by this value in MIKE 21 The MIKE 21 AD solver treats any pollutant or constituent as a scalar and thus does not consider the unit of the pollutant This parameter is used to ensure that the same unit is used in MIKE 11 and MIKE 21 MIKE 11 internally calculates concen trations in g m3 The option M21 _struc_dirtol applies a tolerance to linkage directions for links to MIKE 11 This can be used to force flow directions in MIKE 21 to be aligned with the grid That is if the flow direction is within t
20. simulation MIKE FLOOD User Manual 13 1 Introduction 1 2 How to use this manual MIKE FLOOD offers a range of flexibility Through MIKE FLOOD the modeller can couple a pipe network a river stream network and an over land flow solver into one model This flexibility is reflected in the range of modelling packages integrated in MIKE FLOOD namely MOUSE MIKE 11 and MIKE 21 Further the latter may either be a rectangular grid or a flexible mesh version A MIKE FLOOD model may run with only the MIKE 21 component or it may be augmented with a MIKE 11 and or a MOUSE component This flexibility is also reflected in the manual in that certain sections are only of importance if that specific component has been included Throughout the manual the following icons will be used to indi cate which sections are relevant for which components MIKE 21 rectangular grid MIKE 21 flexible mesh MIKE 11 MOUSE All link types are links between MIKE 21 and either MIKE 11 or MOUSE Further MIKE 21 may either be a rectangular grid version or a flexible mesh version The latter only possible if licensed The various sections unless indicated are applicable to both versions of MIKE 21 14 MIKE FLOOD Standard Link Ss 2 2 1 2 2 GENERAL DESCRIPTION There are five different types of MIKE FLOOD links available Four of these link MIKE 11 and MIKE 21 whereas the last type is reserved for linking a node manhole in MIKE URBAN
21. structure in the previous q point before the coupling point the extrapolation factor is set to 0 Note that this may affect stability of the link e MIKE FLOOD computes discharge from MIKE 11 and distributes it to the associated point s in MIKE 21 If the link in MIKE 21 consists of more points the discharge is distributed uniformly to all points If the depth distribution flag is used flow is distributed according to water depth in each individual cell e The discharge from MIKE 11 influences the continuity equation as well as the momentum equation The direction of the flow is derived from comparison of the orientation of the MIKE 21 grid and the direc tion of the MIKE 11 branch MIKE FLOOD User Manual 59 Ss Tips and troubleshooting e MIKE FLOOD computes the water level from the link point area in MIKE 21 and assigns it to the associated boundary point in MIKE 11 If the MIKE 21 link consists of more points the average value from these points is transferred to MIKE 11 In general more than one linked MIKE 21 grid point will tend to smooth and stabilise a coupling 6 4 Lateral Links ES e Lateral links can cause oscillations in the flow through the link when the difference in water levels between MIKE 11 and MIKE 21 is simi lar To minimize such oscillations use the depth tolerance factor Also consider using a friction coefficient in the links it is considered phys ically correct in situations with vegetatio
22. the flexible mesh the individual elements to be coupled are identified at run time Thus the linkage is independent of the element size The linkage in this case is made up of the coordinates of the end points of the line segments making up the linkage line At run time the linkage line is mapped unto the element faces 7 3 Hydrodynamics Structure Links The structure link takes the implicit terms describing momentum through a 3 point MIKE 11 branch and uses them to replace or modify the implicit terms describing momentum across the face of a MIKE 21 cell In this way the flow properties from one MIKE 21 cell to another are modified to represent a structure Consider the following diagram River branch with one or SS y S S Cel linked to AA downstream S S NS end of branch Cell linked to upstream end of branch Cell faces where momentum equation 1s modified due to link Figure 7 5 Structure Link Diagram The momentum equation from the MIKE 11 q point replaces the x momentum and y momentum equation of the upstream MIKE 21 cell This is the only thing that is modified within MIKE 21 Note that the cells at the downstream end of the branch are only used to extract a water level to be used when evaluating the momentum equation When the MIKE 11 momentum equation replaces the MIKE 21 momen tum equation the implicit terms for the momentum equation within the MIKE 21 cell are replaced Adjustments are made f
23. whether a MIKE 11 set up is to be included A button allows for browsing the parameter file Furthermore the Edit MIKE 11 input button allows for opening the existing MIKE 11 simula tion file for further editing 3 1 3 Urban File name MIKE FLOOD may be used with either MOUSE or MIKE URBAN MOUSE engine It is optional whether an urban model is to be used with MIKE FLOOD Ifa link is to be established the tick box to the left of the file name field should be activated If an urban set up is to be used with MIKE FLOOD the complete urban set up should be established and tested A button allows for browsing the parameter file Furthermore the Edit MIKE URBAN button allows for opening the existing MIKE URBAN set up for further editing If MIKE FLOOD is coupled with MOUSE the button is deactivated and the user must open the MOUSE set up sepa rately Ifa MIKE URBAN set up is used in conjunction with MIKE FLOOD the set up must be preprocessed before launching MIKE FLOOD The pre processing tool is located in the main menu bar under the run menu 3 1 4 Overview of Links The links may be of the following five different types e Standard links the link is the connection between the end of a MIKE 11 branch and a series of MIKE 21 cells or element faces if a flexible mesh is used MIKE FLOOD User Manual 21 Application details e Lateral links the link is the connection between one MIKE 11 river reach within one bra
24. with the water depth and is only active when the water level difference is less then the depth tolerance 3 4 6 Structure Coefficients Coefficients controlling flow through the link structure include the weir coefficient default 1 838 m 2 s the weir exponent coefficient default 1 5 the Manning s n friction coefficient m 3 s and the form loss coef ficient Note that friction can be included in the weir equations see the scientific documentation for more information 3 4 7 External Files If the structure source is EXT an external file is specified If the structure type requires a QH table to be read a gh external file is specified The for mats of both files are shown in Table 3 2 and Table 3 3 Table 3 2 Format of External Structure File File Input Description Example External file from is a comment marker as many comment lines GIS as desired can be included in this file E 0 20 Line 1 Number of entries 100 0 0 0 Line 2 onwards column entries space delimited anes first column is chainage second column is bed level 500 0 0 0 m 1000 0 2 0 i 44 MIKE FLOOD Options for Lateral Links Table 3 3 Format of External QH File File Input Description Example HQH file I is a comment marker as many comment lines 53 as desired can be included in this file 00 10 20 Line 1 Number of upstream levels rows nr and number of downstream levels columns nc s
25. 11 Thus to ensure that both set ups can be viewed at the same time it may be necessary to adjust the working area of the MIKE 11 and the MOUSE set up e Itis possible to pan in the graphical view To do this click in the graph ical view and either right click and select the pan option or use the shift key in conjunction with the left mouse button e The graphics may be exported to the clipboard or saved in a bitmap or a metafile format e Selection of layers bathymetry files and MIKE 11 nwk file to be included in the graphical view e The display properties for the graphical view are accessed through this sub menu e Branches may be automatically linked to the MIKE 21 set up e Images may be added or removed from a set up e Cells lying in the main river bed between the left and the right levee may be blocked out This may be done to ensure that mass is not dou ble counted Note this feature is only available for the rectangular grid version of MIKE FLOOD e Nodes in the urban set up may be linked to the MIKE 21 grid cells ele ments Information on the individual cells To obtain information on the individual cells simply click on a cell in the graphical view The j k coordinates will be displayed in the lower infor mation bar of MIKE Zero see Figure 3 9 28 MIKE FLOOD The graphical layout e j 7 k 3 z 1 069569 Figure 3 9 Clicking a particular cell displays the information in the lower MIKE Z
26. 2 1 35 1 356 Below 1 35 0 50 100 150 200 250 300 250 01 01 90 12 33 20 Time step 1000 of 1000 Figure 8 21 Flow Direction Test Results Water Depth and Velocity As shown the direction of flow discharging from each linkage point is consistent with the branch alignment The link points that have land or zero flow links behind them show slightly different flow patterns As a result of the zero flow links water levels in the bottom right corner are H Water Depth m Im Undefined Value lower than the rest of the model This is driving flow through the structure links An AD simulation was also performed Initial concentration was set to zero and inflows apply a conservative concentration of 100 The contour plot below shows results MIKE FLOOD User Manual 95 Examples Graphical Items 5 Color point ES X Width point pollutant H Above 100 957 100 9139 957 87 09 91 39 62 78 87 09 96 48 35 52 65 4404 48 35 5 304 9609 1 5304 Below 1 Undefined Value 0 50 100 150 2 25 a 5 5i 550 0101 0 15 20 00 Time step 50 of 83 Figure 8 22 Flow Direction Test Results Concentration The flow directions from the links create a slight whirlpool pattern The zero flow links are also zero concentration links the plot above demon strates that the zero flow links are a barrier to advection and dispersion Finally a check of mass conservation in the model is mad
27. 21 cells MIKE FLOOD Hydrodynamics Lateral Links e M11 branch with h points Single h point lies within internal structure influence all flow into h point No h points lie within internal structure influence interpolate flow into two nearest h points distance Internal structures DH Three h points lie within internal structure influence distribute flow to 4 amp each depth lw Y dependent Method of flow q distribution into M21 cells Pn p i same as for M11 Figure 7 3 Lateral Link Interpolation of Flows This approach allows a high level of flexibility when designing the lateral link However it is likely that a similar distribution of MIKE 11 points MIKE 21 cells and internal structures will produce the most accurate solu tion 7 2 1 Automated cell selection The automated cell selection tool may be used for the centre line or the left or the right levee line The cell element selection only varies in the way the line is defined The centre line is defined through the digitised points in the MIKE 11 set up The construction of the levee lines follows through a number of fully automated steps see Figure 7 4 1 The cross sections located within the user selected reach are placed according to either the geo referenced coordinates or the chainage The latter only if the coordinates are not present or applied 2 Ifthe cross sect
28. 6636 0 6795 0 6477 0 6836 0 5318 0 6477 06159 06318 06 0 6159 Seow 06 Unde ned Value 372000 06 23 02 13 30 00 Teme step 27 of 27 Figure 8 31 Floodplain Demonstration Water Surface and Velocities near peak of flood Water Level Upstream of Road Max 122 Water Level Downstream of Road Max 106 106 4 Peak WS Water Level 1 Head Drop Across Rad Max 0 38 0 16 at Peak US Water Level Eos Rar 06 os 02 0 02 co 21 00 23 05 09 00 23 05 21 00 24 05 09 00 24 05 21 00 Oscharge in Main River Channel Max 45 42 46 3 at Peak US W ter Level 40 Oscharge in Culvert 1 North Side Max 1 7 174 Peak WS Water Level 5586 Dscharge in Qulvert 2 South Side Max x 3 8 38a Peak WS Water Level 3 30 E 25 20 B16 a 10 5 0 on 22 05 21 00 23 05 09 00 23 05 21 00 24 05 09 00 24 05 21 00 Figure 8 32 Flood plain Demonstration Results Water Levels and Flows at Road Embankment 104 MIKE FLOOD Urban examples Ss 8 7 Urban examples Two urban examples are also included with the installation The first of these urban examples is based on an area in Bangkok and is a reduced model from the full model The present model represents a sub set of the sewer network and further only couples the 2D and the 1D sewer model at four locations see Figure 8 33 Note that the example is available both as a MOUSE version and a MIKE URBAN version
29. D prediction The findings of this test show that the lateral links are mass preserving and behave as expected Further the test highlights the importance of using lateral links in situations where there is a significant water level gradient in the in bank river channel 88 MIKE FLOOD Lateral Link 1 y Finally an AD simulation is added to the test To do this add the AD com putation to MIKE 11 and MIKE 21 then set the MIKE FLOOD Coupling Type to be HD and AD The time series plot displays pollutant concentrations entering the upstream boundary and flowing out the two downstream boundaries g m 3 Time Series Concentration Concentration dii RM21 500 00 POLLUTANT 5 LM21 500 00 POLLUTANT LATM21 0 00 POLLUTANT 30 0 20 0 10 0 0 0 03 00 00 06 00 00 09 00 00 12 00 00 15 00 00 18 00 00 Figure 8 12 Lateral Link Test 1 Results Time Series of Concentration Also contour plots of concentration in the MIKE 21 domain are shown at two instances MIKE FLOOD User Manual 89 LEA Examples 0 20 400 600 0 200 400 01 01 03 01 20 00 Time steo B of 100 01 01 03 16 40 00 Time steo 100 of 100 Figure 8 13 Lateral Link Test 1 Results Concentration 8 3 Lateral Link 2 This is a test to ensure that the structure equation in the lateral link is con sistent with that in a standard MIKE 11 simulation The first test is a sim ple MIKE FLOOD model that has a MIKE 11
30. EALED PACKAGE OR INSTALLING OR USING THE SOFTWARE YOU HAVE ACCEPTED THAT THE ABOVE LIMITATIONS OR THE MAXIMUM LEGALLY APPLICA BLE SUBSET OF THESE LIMITATIONS APPLY TO YOUR PUR CHASE OF THIS SOFTWARE Printing History November 2006 Edition 2007 MIKE FLOOD User Manual INTRODUCTION 0 020 0 00 000 00000 2 ee ee 11 1 1 General Approach to Modelling with MIKE FLOOD 12 1 2 Howto use this manual 14 GENERAL DESCRIPTION 0 0 0 000000 0004 15 2 1 Standard Link 0000000000000 ee ee 15 2 2 Lateral WINK 22 6 ek ee ee a Re ee 15 2 3 Structure Link Implicit 4 e 6 2 bese ee ke ee eee Ra 16 2 4 Urban Link 0 00000 000002 ee ee 17 2 5 Zero Flow Link X and 66 2dec e8 dddada dower ed oat 18 APPLICATION DETAILS 19 3 1 Deftones sese a eves e bee ees dee di Be eee ha 19 3 1 1 MIKE 21 FileName 04 20 3 1 22 MIKE 11 File Name 04 21 3 1 3 UrbanFilename 000 21 3 1 4 OverviewofLinks 0 0 000 4 21 Sele O Sears Bd See oe ee 23 3 1 6 Coupling Type lt lt lt 54 ce ence eee eee Rees 23 3 1 7 MIKE 11 River Name Node ID and Chainage 24 3 1 8 MIKE 21 Area Number 25 3 1 9 MIKE 21 Coordinates o 25 3 2 The graphical layout lt oo eee 26 3 2 1 Information on the
31. IKE FLOOD appli cation see mf2 couple 86838 a MIKE 11 858588580 Figure 8 10 Lateral Link Test 1 Layout 2 MIKE FLOOD User Manual 87 Examples The MIKE 11 test has two branches representing lateral flow aligned equally at the centre of the upstream branch Comparison of discharges from the downstream branches for the MIKE FLOOD and MIKE 11 tests are presented below m 3 s Time Series Discharge Discharge LM21 25 00 RM21 25 00 LM11 25 00 RM11 25 00 00 00 00 02 00 00 04 00 00 06 00 00 08 00 00 10 00 00 1 1 2003 Figure 8 11 Lateral Link Test 1 Results Time Series of Discharge 2 Both the MIKE FLOOD and MIKE 11 simulations preserve mass with the amount of flow leaving the system exactly the same as the amount entering However the MIKE FLOOD and MIKE 11 simulations each give different distributions between the left and right banks There are sev eral possible reasons for this e MIKE FLOOD accounts for the water level gradient in the channel This increases the accuracy of over bank flow calculations e MIKE FLOOD calculates weir flow across each calculation point 20 in total whereas the MIKE 11 simulation calculates weir flow at one calculation point e Itis possible that additional losses from 2D effects such as eddy for mations in MIKE 21 are contributing to the lateral link structure losses This may create a variation between a MIKE 11 prediction and the MIKE FLOO
32. IKE VIEW look at the longitudinal profile of the upstream branch Lil Viam Laval 14 200 160945 Dacia nfs mo Figure 8 7 Lateral Link Test 1 Results Water Level and Flow Profile Similarly the lateral discharges can also be presented tick the Lateral Inflows button in the Additional Output Menu in HD Parameters trade toda Lee 14 2003 1611945 Escapa nta Figure 8 8 Lateral Link Test 1 Results Lateral Flow Profile Last but not least a check of the mass in the system can be made by comparing the total discharge into the model the upstream inflow from the upstream branch with the discharge out of the model from the down stream branches As shown 100 m3 s enters from upstream The flows are distributed so that 47 76 m s flows through the left branch and 52 24 m3 s through the right 86 MIKE FLOOD Lateral Link 1 ASS m 3 s Time Series Discharge Discharge uae LATM21 25 00 LM21 475 00 90 0 RM21 475 00 70 0 60 0 00 00 00 02 00 00 04 00 00 06 00 00 08 00 00 10 00 00 1 1 2003 Figure 8 9 Lateral Link Test 1 Results Time Series of Discharge For comparison the same setup has been done using MIKE 11 For the MIKE 11 setup the left and right basins are represented using branches Flow from the upstream branch to the basins occurs through two addi tional branches with cross sections representing the bank levels The MIKE 11 test has been combined with the original M
33. M2 1 Link from every h point in branch to every linked M21 cell G Figure 2 2 Application of Lateral Links 2 3 Structure Link Implicit The structure link takes the flow terms from a structure in MIKE 11 and inserts them directly into the momentum equations of MIKE 21 This is fully implicit so should not affect time step considerations in MIKE 21 The structure link is useful for simulating structures within a MIKE 21 model The link consists of a 3 point MIKE 11 branch upstream cross section structure downstream cross section the flow terms of which are applied to a MIKE 21 cell or group of cells An example is shown 16 MIKE FLOOD Urban Link LEA 11 Branch with structure one or more defined at q point tructure Link Flow over road is modelled using Mil hgh branch representing a structure s implicitly inserted into M21 flow equations Flow conditions from Mii can either replace flow in M21 or be added to existing M21 flow Figure 2 3 Application of Structure Links Only to be used for a rectangular grid 2 4 Urban Link The urban link is designed to describe the interaction of water when a manhole is over topped or when overland flow enters a sewer storm water network Flooding from Mike 21 Sewer System Figure 2 4 Flooding from MIKE 21 into a non surcharged sewer system MIKE FLOOD User Manual 17 a or General description Flooding from surcharged sew
34. ODUCTION MIKE FLOOD is a tool that integrates the one dimensional models MOUSE MIKE URBAN MIKE 11 and the two dimensional model MIKE 21 into a single dynamically coupled modelling system Using a coupled approach enables the best features of both a one dimen sional and two dimensional models to be utilised whilst at the same time avoiding many of the limitations of resolution and accuracy encountered when using MIKE 11 MOUSE or MIKE 21 separately Special features of MIKE FLOOD include Momentum preservation through links Lateral links enabling simulation of over bank flow from river channel to flood plain Comprehensive hydraulic structures package Implicit structure links Manhole links whereby the interaction of the sewer storm water sys tem may interact with the overland flow GIS integration Links possible along any alignment in MIKE 21 not just horizontally or vertically A graphical user interface standard MIKE ZERO allowing for easy data input and output as well as data preparation and analysis A thorough on line help system user manual and technical reference documentation Support and continuing commitment from DHI Water and Environ ment There are many advantages to using MIKE FLOOD and many model applications can be improved through its use including Flood plain applications Storm surge studies Urban drainage Dam break Hydraulic design of structures Broad scale estuarine applications
35. Replace No 1 000 Structure l Replace No 1 000 Structure l Replace Yes 1 000 Structure l Replace Yes 1 000 a fojojajojaje jojn Figure 3 19 Overview of options for standard and structure links Note that the first column is carried over from the Definition page and cannot be edited This is an abbreviation for Momentum Factor The Momentum Factor is applied to the momentum terms in MIKE 21 for standard links A value of 1 means full momentum transfer through the link while a value of 0 means that momentum transfer is not guaranteed Note that even if the factor is set to 0 the source term applied to the conti nuity equation still creates some momentum While this is sufficient in cases where conservation is not critical such as over weir structures or for very large 2D cell size relative to the river flow capacity it will not be accurate enough for all cases On the other hand in some instances model stability may be improved by removing the momentum terms Momentum is disabled for the lateral links because of the conceptual diffi culties associated with lateral flows in a 1D model For the structure links momentum is preserved via the implicit terms and this parameter is not applicable This is an abbreviation for Extrapolation Factor For standard links the extrapolation factor has a default value of 1 5 This factor controls the time predictor in MIKE 11 which establishes MIKE 21 link values for the next time step If f
36. WATER amp ENVIRONMENT MIKE FLOOD 1D 2D Modelling User Manual DHI Software 2007 G f share MikeZero new source manuals mflood MIKEFLOODCover fm 22 January 2007 6 42 am Please Note Copyright This document refers to proprietary computer software which is protected by copyright All rights are reserved Copying or other reproduction of this manual or the related programs is prohibited without prior written consent of DHI Water amp Environment DHI For details please refer to your DHI Software Licence Agreement Limited Liability The liability of DHI is limited as specified in Section HI of your DHI Software Licence Agreement IN NO EVENT SHALL DHI OR ITS REPRESENTATIVES AGENTS AND SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSO EVER INCLUDING WITHOUT LIMITATION SPECIAL INDIRECT INCIDENTAL OR CONSEQUENTIAL DAMAGES OR DAMAGES FOR LOSS OF BUSINESS PROFITS OR SAVINGS BUSINESS INTERRUPTION LOSS OF BUSINESS INFORMATION OR OTHER PECUNIARY LOSS ARISING OUT OF THE USE OF OR THE INA BILITY TO USE THIS DHI SOFTWARE PRODUCT EVEN IF DHI HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES THIS LIMITATION SHALL APPLY TO CLAIMS OF PERSONAL INJURY TO THE EXTENT PERMITTED BY LAW SOME COUN TRIES OR STATES DO NOT ALLOW THE EXCLUSION OR LIMITA TION OF LIABILITY FOR CONSEQUENTIAL SPECIAL INDIRECT INCIDENTAL DAMAGES AND ACCORDINGLY SOME PORTIONS OF THESE LIMITATIONS MAY NOT APPLY TO YOU BY YOUR OPENING OF THIS S
37. actor is set to zero the same value at n 1 will be used as 38 MIKE FLOOD Options for Standard Structure Links at n Note If the last q point in the linked branch is a structure this factor is set to zero by the calculation kernel The extrapolation factor is not applied for lateral links or for structure links For more information see the scientific documentation 7 1 Hydro dynamics Standard Links p 65 3 3 3 Add Replace Momentum Terms This option is available for structure links e Ifthe momentum terms are replaced flow conditions calculated in MIKE 11 override flow conditions in the MIKE 21 cell e If momentum terms are added the flow conditions calculated in MIKE 11 are added to the flow conditions in the MIKE 21 cell To illustrate consider a situation where a weir structure in MIKE 11 repre sents a road embankment in a MIKE 21 grid similar to that shown in Figure 2 3 The MIKE 11 structure flow would replace the MIKE 21 flow conditions Next consider the same situation except with a culvert located under a section of the road The culvert structure would be modelled in MIKE 11 in a separate branch to the weir and added to the flow conditions in the MIKE 21 cells As long as this culvert structure link is listed in the cou pling file after the weir structure link both weir and culvert flow would be included in MIKE 21 Consider a third possibility where the road embankment is instead simu
38. al smoothing factor The exponential smoothing factor may be used for links which are misbe having causing oscillations The exponential smoothing factor works by applying a weight to the transferred water level from MIKE 21 to MIKE 11 The expression reads Hym a Hy 1 1 aH n 7 12 where a is the smoothing factor Hy is the MIKE 11 water level Hip the MIKE 21 water level and n is the time step By applying this expres sion n times the water level may be given as m Hyn 9H 0ta Y 10 Hypo 11 7 13 i 0 Using the above expression a criteria for selection of the smoothing factor may be obtained Assuming that the water level in MIKE 21 in constant then the number of time steps n it will take the MIKE 11 water level to be within a fraction f of the MIKE 21 water level is given by _ logf n E 7 14 Thus the smoothing factor should be chosen in relation to the time scale at which the dynamics change in the model MIKE FLOOD User Manual 73 Scientific background 7 4 Hydrodynamics Zero Flow Links If the link type is a XFLOW 0 link the x direction momentum across the right face of the MIKE 21 cell is set so that g 0 This is done by modify ing the implicit terms n n n 1 ais budia emah dyn 7 15 421 Cm21 dy 0 7 16 Du 1 7 17 Similarly if a YFLOW 0 link the y direction momentum across the top face of the MIKE 21 cell is set to g 0 7 5 Hydrodynamics Ur
39. aximum and minimum value is available to gradually apply the flow conditions over a range to minimise instabili ties Note that the feature is only available with a MIKE 11 link If the minimum and maximum values are set to zero the activation depth facility is inactive 3 3 6 Exponential Smoothing Factor The parameter introduces an exponential smoothing of the water level val ues transferred from the MIKE 21 grid to the structure A value of 1 indi cates no smoothing whereas a value closer to 0 creates strong smoothing in the model The smaller the value the greater the smoothing will be The parameter impacts the dynamics by smoothing out steep gradients in time through the links In general the exponential smoothing factor should be adjusted when a structure exhibits unstable behaviour oscillates wildly In general the fol lowing approach should be followed if a structure shows instability 1 Set the exponential factor to 0 2 0 4 2 Run the model 3 If a structure still misbehaves i e causes a blow up OR the discharge hydrograph is very noisy then check the results file the MIKE 11 struc ture setup MIKE 21 topographic grid the coupling etc for problems and inconsistencies 4 Rerun the model if changes are made 5 If the structure still misbehaves then the smoothing factor may be fur ther reduced Note that a small smoothing factor will cause a time lag in the transfer of the values fro
40. ban links The exchange of water Oym gt 1 at the inlet can be computed in three dif ferent ways Ce e Orifice equation e Weir equation e Exponential function The orifice calculation is given by Qumi sign Hy Hy2 CMin A Ap 2g Hy Hgo 7 18 for Qum2il lt Qmax Where Qym21 Flow from sewer to MIKE 21 grid point Hy Water level in sewer system Ayo Water level on the ground An Cross sectional area of manhole Ax Cross sectional area of inlet C The weir coefficient 74 MIKE FLOOD Advection Dispersion Ss The weir equation depends on whether there is flooding on the surface or not If the surface is not flooded at the time then it is calculated as a free flowing weir Quma Hy Ayn Woresi 28 Hy H yor 7 19 for Qym21 lt Qmax Where Wes iS crest width to be used in the equation If the surface is flooded then the weir is calculated as a submerged weir round Quma Hy Hya1 W erestN 28 Hy Fal E if west 7 20 Hy Ayr The last function for computing the flow between MOUSE and MIKE 21 is given by Qum S Hy Fig 7 21 for Qum2il lt Qmax Where So Simple scaling factor Exp Exponent Note that eq 7 21 the values of H are given in meters and the discharge is given in m s There is an option to suppress oscillations by use of the QdH factor The value corresponds to the water level difference at which the suppression is applied The suppression is design
41. both simulations 2 43 m and 2 44 m These variations may be due to the missing momentum transfer across the lateral links Steady state discharge is the same for both simulations 100 m3 s indicating that mass is conserved through the links Notice the oscillations in the discharge at the downstream end of the MIKE 21 basin This is a result of reflections in the MIKE 21 model created as the initial wave front produced by the rising discharge enters the MIKE 21 domain The water level contours and current vectors in MIKE 21 for each simula tion are presented below Notice that there is a slight variation in flow dis tributions in the laterally linked case the variations are shown by the velocity vectors in the link cells MIKE FLOOD Flow Direction q AAA T T i i i a a 1000 500 D 500 1000 1500 2000 01 01 90 20 20 00 Time step 100 of 100 Figure 8 18 Lateral Link Test 2 Results Standard Link 800 e0 400 A T T 1000 500 D 500 1000 1500 2000 01 01 90 20 20 00 Time step 100 of 100 Figure 8 19 Lateral Link Test 2 Results Lateral Link 8 4 Flow Direction This test was initially designed to test links applied in a direction that is not aligned with the MIKE 21 grid However it evolved into a demonstra tion of all the link types available in MIKE FLOOD The test consists of a square MIKE 21 basin with a variety of MIKE 11 branches discharging flow into it Th
42. downstream is 0 m To each of these setups an upstream flow hydrograph is applied which has a peak discharge of 2000 m3 s A downstream water depth of 4 m is maintained 1200 1990 01 01 Figure 8 25 Floodplain Flow Test Upstream Hydrograph The water level at the upstream end of each of the four models is pre sented Water Level m 12 10 1 01 08 00 1 01 1200 1401 16 00 1401 20 00 201 00 00 2 01 0400 201 08 00 201 120 201 16 00 201 20 00 Figure 8 26 Floodplain Flow Test Results Upstream Water Level Further the discharge at the downstream ends of each model is presented with the upstream hydrograph MIKE FLOOD User Manual 99 LEA Examples Discharge md Figure 8 27 Floodplain Flow Test Results Downstream Discharge For each test case the upstream water levels are reasonably consistent with the other However the MIKE 21 simulation predicts a higher water level suggesting more losses along the length of the model The downstream discharges are also reasonably consistent although again the MIKE 21 simulation and to a lesser extent the MIKE FLOOD simulation have a reduced more dampened discharge peak This again suggests more losses in the model A possible reason for this variation in model predictions between MIKE 11 and MIKE 21 could be due to wetting and drying in MIKE 21 8 6 Floodplain Demonstration This example is available
43. e With 8 sepa rate inflow branches the total flow rate into the system is 80 m3 s The resulting discharge through the draining lateral link in the centre of the basin is shown below At the completion of the simulation the flow rate shown in MIKE VIEW at the last point in the lateral flow branch is 77 m3 s While this may appear to be a mass loss error in fact it is a minor presentation bug caused by having a lateral link at the last h point in the branch The discharge presented in MIKE VIEW is at the last q point As lateral flows are added to the h points this means that the flow rate of 77 m3 s does not include an additional 3 m3 s entering the last h point To check this rerun this simulation with the lateral link connected between chainage 20 to 100 m on the MIKE 11 branch branch9 The dis charge at the last point will then be presented as 80 m3 s indicating that mass is preserved MIKE FLOOD Flood plain Flow 8 5 Flood plain Flow This is another test of the lateral links It compares model performance over a broad flood plain application This is a simplified representation of a typical lateral link application flood plain in MIKE 21 river channel in MIKE 11 and flow between them in MIKE FLOOD The test consists of four separate setups e MIKE FLOOD river channel modelled in MIKE 11 footplates in MIKE 21 connected with MIKE FLOOD lateral links mf couple e MIKE 11 single branch for main channe
44. e Weir Formula 2 Honma is h O wCh h for lt 2 3 7 30 h Dei Bor hh toe Oe 2 2 1 2 h MIKE FLOOD User Manual 77 Scientific background The first equation is free overflow identical to Formula 1 with free over flow while the second is for submerged conditions Both equations are derived from the equation for form loss across a struc ture where Ah 2 7 31 If a friction loss is added this becomes 2 Ah 7 32 where 2 2gL a 7 33 1 Ef Friction coefficient L length of structure and n Manning s number Expanding o w hE 1 34 This equation is similar in form to Weir Formulae 1 and 2 for free over flow except that the weir coefficient is replaced 2 C ae E 7 35 MIKE FLOOD Inclusion of Friction Term in Weir Formulae 1 and 2 Honma Assuming that the entrance exit losses are the same a new weir coeffi cient Cycan be derived from the original coefficient C and the additional friction 2 2g c Pac 28 7 36 q i e 2 2 C l g g 7 37 T io So the existing equations for weir flow calculations can be used except that the weir coefficient is modified according to Gs E_ 7 38 2 2gLn 28 C 6 mE 1 This equation is applied to the weir calculations in the lateral link specifi cations MIKE FLOOD User Manual 79 Scientific background 80 MIKE FLOOD Standing Wave Ss 8 EXAMPLES The e
45. e branches are aligned at different angles to the MIKE 21 grid and consist of standard and lateral links In the centre of the basin is a lateral link that drains the basin Using the zero flow links the bottom right corner has been isolated from the rest of the basin except for two structure links on each side The structure links are connected to 3 point MIKE 11 branches with a weir Some of the link cells in MIKE 21 are completely surrounded by wet cells Others have land cells or alternatively zero flow links inserted behind the link cells The MIKE 21 grid size is 10 m and the initial water level is 1 m A con stant discharge of 10 m3 s is applied to the upstream end of each branch and the time step in both MIKE 11 and MIKE 21 is 2 s MIKE FLOOD User Manual 93 Examples 450 0 Nal Links ONG Lateral Links Standard Links Standard Links 100 150 200 250 300 360 400 450 500 550 Figure 8 20 Flow Direction Test Layout The HD simulation run to steady state conditions is presented below 94 MIKE FLOOD Flow Direction LEA Above 1 494 1 487 1 494 1 481 1 487 1 475 1 481 1 469 1 475 1 462 1 469 1 456 1 462 1 45 1 456 1 444 145 1 438 1 444 1 431 1 438 1425 1471 1419 1 425 1 413 1 419 1 406 1 413 14 1 406 1 304 14 1 388 1 394 1 381 1 389 1 375 1 381 1 369 1 375 1 362 1 369 1 356 1 36
46. e cells should be in the same sequence as increasing chain age specified in MIKE 11 Further note that MIKE FLOOD only allows lateral linked cells which are ordered such that any two sequential cells are adjacent Thus a sequence Jj K J2 K2 must satisfy two of the follow ing equations K K 1 K K 1 ad 6 1 J J 1 IS K Ky The valid cells are illustrated in the figure below MIKE FLOOD User Manual 25 LEA Application details Valid locations for Ja Ka Figure 3 6 Valid locations for a cell JK being adjacent to cell J4 K1 If the flexible mesh version of MIKE 21 is used the coordinates table TI holds the actual coordinates of the linkage line along with a third column y containing chainage values along the river The chainage column controls how the linkage points are mapped onto the river 3 2 The graphical layout MIKE FLOOD includes a graphical view that displays the bathymetry the modelled MIKE 11 branches the MIKE URBAN or MOUSE pipe net work along with additional image files The graphical view gives a clear overview of the location of the links in MIKE FLOOD Further the graph ical view has a number tools for automatically selecting the linkage points cells in MIKE 21 26 MIKE FLOOD The graphical layout 8128400 8128200 8128000 p Previous Zoom Next Zoom 8127800 Gn 8127600 Copy to Clipboard fe A Save to Metafile 8127400 3 Py Save t
47. e invert is used rather than water level This could be useful if using a CELLTOCELL method with different bed levels in each cell but similar flow characteristics This is read in from an external file e FORMLOSS Standard velocity head form loss equation Ah v 2g The form loss coefficient can include a friction com ponent The WEIR type is the default See the Scientific Documentation for more information 3 44 Source The structure source determines where the levee level geometry informa tion comes from Depending on whether a rectangular grid or a flexible mesh is used the lateral links are treated slightly differently 42 MIKE FLOOD Options for Lateral Links _ Ae Rectangular Grid e M11 Structure points are defined at each river computation h point The cross section left or right bank markers marker 1 or marker 3 are extracted from the cross section database and used as the link structure bed levels Bank levels at h points without a cross section are interpo lated e M21 Structure points are defined at each MIKE21 cell Bed levels from MIKE21 cells are used as the structure bed levels e HGH Structure points are defined at either each MIKE 11 computa tional h point or each MIKE 21 cell whichever has the highest resolu tion The structure bed levels are the highest of the MIKE 11 bank markers and the MIKE 21 cells e EXT Information is read from an external ASCII file The HGH source type is
48. ed for cases where the pressure level in the sewer system is close to the water level in MIKE 21 and may be applied individually at each urban coupling Ifa value of 0 0 is given then no suppression is applied 7 6 Advection Dispersion Concentrations of AD components are transferred explicitly between MIKE 11 and MIKE 21 depending on the direction of the flow For stand ard links with flow from MIKE 11 to MIKE 21 the concentration of the AD component is imposed as with a standard MIKE 21 source i e as a flux of mass into the MIKE 21points MIKE FLOOD User Manual 75 SE Scientific background n oy Cm2 _ yT a n a a1 Sy 7 22 When flow is going from MIKE 21 to MIKE 11 the modification to the AD equation in MIKE 21 is Vip a A 0 Chon 7 23 The corresponding boundary condition in MIKE 11 can be either a trans port boundary or a concentration boundary as usual Furthermore a mix ing coefficient can be defined as normal For lateral links the mass of the AD component being transferred is calcu lated from the lateral discharge and the concentration in MIKE 11 or MIKE 21 depending upon flow direction This is then applied as a source or sink term in the branches and cells The source term into MIKE 21 is as for the standard links For MIKE 11 the one dimensional advec tion dispersion equation is GAC QC 4p OC __ EP Ox av AKC Cq 7 24 where C is concentration D dispersion coefficient
49. el results with and without the road embankment could give an indication of the likely impacts Also the performance of the culverts could be assessed maybe more are needed Note that this is a demonstration model not a real example Other model ling considerations that could be of relevance in this example include e The MIKE 21 grid does not cover the entire floodplain width e The proposed road crosses over the main channel Any hydraulic effects bridge structure or pier losses created by this situation are ignored e The roughness parameter on the floodplain has been set to a constant value of M 20 The roughness may actually be varying spatially par ticularly if there are a range of land use patterns e The upstream and downstream MIKE 11 branches only represent the main channel They do not include the flood plains The flood plain example is also available as a flexible mesh version Note that the flexible mesh version does not have zero flow links available since these may easily be accomplished through the use of internal closed boundaries The latter has also been done for the flood plain example to model the road cutting through the flood plain MIKE FLOOD User Manual 103 e Examples Surtsce Elevation m Aboe 1394 1 388 1394 1352 1268 1 736 1252 19 16 1206 122 1 189 1205 14 173 1189 4457 1473 11441 1487 0751 0775 0 7432 0 7591 07373 0 7432 07914 07273 06055 07114 0 6795 0 6955 0
50. els flood plain features etc e The type of links to be used e The geographical projection used must be identical for MIKE 11 MOUSE and MIKE 21 4 2 Setup and Run 1D Models MIKE FLOOD is a combination of MIKE 11 MOUSE and MIKE 21 Set up the individual models separately then join them together using MIKE FLOOD It should be possible to completely define the 1D models that will be linked in MIKE FLOOD This should be done to ensure that no errors MIKE FLOOD User Manual 49 e Running MIKE Flood recommended steps exist in the 1D models While the results of the simulation will not be cor rect they may provide an indication of potential problems 4 3 Setup and Run MIKE 21 Model As for the 1D setups ensure no errors exist in the MIKE 21 definition files Run the simulation and ensure that the results are reasonable For flood plain applications this may include running a completely dry set up with closed boundaries 44 Setup MIKE FLOOD The model layout should already be decided upon and the individual models should already have the components ready for running the MIKE FLOOD model This step is to create the MIKE FLOOD couple file and define the links to be applied 4 5 Run MIKE FLOOD Simulation Note that the standard links and the lateral links are explicit Courant con ditions cannot exceed 1 It is this initial simulation where the Courant conditions are likely to be encountered and any stability problems
51. er level at the MIKE 21 boundary is 2 m so water depth is 2 m in the upstream branch and in the MIKE 21 grid The simulations are performed using a time step of 30 s explicit Courant conditions The upstream flow boundary in MIKE 11 gradually rises from 0 m3 s to 100 m3 s and remains steady at this flow rate The resulting water level at the upstream end of the MIKE 11 branch and the discharge at the downstream end are presented below MIKE FLOOD User Manual 91 Examples 2 55 2 45 2 35 E 3 2 25 Z 2 2 45 2 05 Mater Level Upstream Standard Link Value at End of Simulation 2 43 cm iater Level Upstream Lateral Link Value at End of Simulation 2 44 1 95 11 45 12 45 13 45 1445 15 45 1645 17 45 18 45 19 45 20 45 21 45 Figure 8 16 Lateral Link Test 2 Results Time Series of Water Level Diacharge msi 2 Discharge in Upstream Branch Standard Link Value at End of Simulation 100 0 Discharge in Upstream Branch Lateral Link Value at End of Simulation 1000 Downstream Discharge from MIKE 21 Standard Link Value at End of Simulation 100 0 Downstream Discharge from MIKE 21 Lateral Link Value at End of Simulation 100 0 1145 12 45 1345 14 45 15 45 16 45 17 65 18 45 19 45 20 45 21 45 Figure 8 17 Lateral Link Test 2 Results Time Series of Discharge There is a slight variation in water levels as the discharge increases but the steady state levels are similar for
52. er system Flooding from Mike 21 Sewer System Figure 2 5 Flooding from a surcharged sewer system into MIKE 21 The link is designed such that one or more cells elements in MIKE 21 may be linked to a manhole node in MOUSE 2 5 Zero Flow Link X and Y A MIKE 21 cell specified as a zero flow link in the x direction will have zero flow passing across the right side of the cell Similarly a zero flow link in the y direction will have zero flow passing across the top of the cell The zero flow links were developed to complement the lateral flow links To ensure that flood plain flow in MIKE 21 does not travel directly across ES a river to the opposite side of the flood plain without passing through MIKE 11 zero flow links are inserted to block MIKE 21 flows An alter native to using the zero flow links is to apply land cells which depending upon grid resolution may not be appropriate Another useful application of zero flow links is to represent narrow block ages on a flood plain such as roads and levees Rather than using a string of land cells a string of zero flow cells can be used Note this link is only available when linking to MIKE 11 18 MIKE FLOOD Definition _ AS 3 APPLICATION DETAILS Any combination of links can be used in a MIKE FLOOD simulation All the information relating to the MIKE FLOOD links is contained in one file the coupling file file extension COUPLE The MIKE 11 MIKE 21 and MOUSE
53. ero bar 3 2 2 Add Remove Layers The graphical view displays all bathymetry files found in the MIKE 21 file along with the branches found in the MIKE 11 network file Addi tional bathymetry files and MIKE 11 network files may be displayed if needed The sub menu has two tabs The first of these Figure 3 10 con trols the model files to be displayed and the second controls the display order of all files including images and colour legends MIKE FLOOD User Manual 29 y Application details Add Files to Project Overlay Manager O mewe File name MIKE 21 Bathymetry File y C MIKEZEROYWeviSourcelExamplelMFloodiFloodple 2 MIKE 11 Simulation File _ C MIKEZEROWev Source Example MFlood Floodple Cancel Help Figure 3 10 Files included in the set up The files from the coupled set ups are included by default Additional bathymetry files mesh files and MIKE 11 or Urban files may be added 30 MIKE FLOOD The graphical layout e Add Files to Project Overlay Manager Overlay drawing order Overlay name Overlay type photo_mga_2m gif World Image Overlay ArcView Grid Data 2 D Rotated Orthogonal Grid Overlay ArcView Grid Data m Color Legend Overlay M11 Network Overlay M11 Network Overlay Display W144 OK Cancel Help Figure 3 11 The overlay manager controlling which graphical themes to be dis played as well as the order of the themes The latter may be changed through
54. es that the water body within the main river is not included twice in the coupled model The blocking out of cells requires the user to edit the MIKE 21 bathymetry in the grid editor The blocking out is done by setting the cell level equal to the land value used in the particular bathymetry The MIKE FLOOD interface can based on the cross sectional widths select the cells lying within the main river The selection is exported to a so called selection file This selection file may then subsequently be used in the grid editor to edit the level of cells within the main river bed To access the selection tool for blocking out cells simply right click in the graphical view and select the Block out river cells menu item The dialog that appears is shown in Figure 3 16 MIKE FLOOD User Manual 33 Application details The tool is applied to each river reach separately The reach is selected based on the river name the topo ID and the upstream downstream chani ages The cells lying within the left and right linkage lines are exported to the file specified in the selection file field Note that the selection file is a dfs2 file containing the 2D grid with a value of 1 in all selected fields g a E 3 2 amp z e 50 100 Grid spacing 1 meter 01 05 2005 12 00 00 Time step 0 Layer 0 Jik Projection Figure 3 14 A selection file opened in the grid editor of MIKE Zero Since MIKE FLOOD may be used with
55. flow is described through a weir equation e Exponential function The flow is governed by a simple exponential function Depending on the calculation method used additional information is required This parameters gives an upper limit on the discharge that can flow through the urban link If the exchange calculated from the flow equation is above this value the discharge is reduced to this value MIKE FLOOD User Manual 47 asker Application details 3 5 4 3 5 5 3 5 6 3 5 7 Inlet area The inlet area is only used when applying the orifice equation for describ ing the flow exchange between the urban and the 2D grid mesh The greater the cross sectional area the greater the conveyance capacity of the coupling This parameter corresponds physically to the area of the man hole cover Crest width The crest width is used when the flow exchange is described through a weir equation The weir crest should be typically be the circumference of the manhole cover Scaling factor Only applicable if the simple exponential expression is used to describe the flow exchange The scaling factor has a linear effect on the discharge Thus an increase in this value will generate a larger flow for a certain water level difference in the urban and the MIKE 21 model Exponent factor Only applicable if the simple exponential expression is used to describe the flow exchange An increase in the exponent factor has a strong impact on t
56. he discharge An increase in this value will generate a larger flow for a certain water level difference in the urban and the MIKE 21 model 48 MIKE FLOOD Define Model Layout Ss 4 RUNNING MIKE FLOOD RECOMMENDED STEPS Errors and inconsistencies in a model setup will occur While every effort has been made to produce clear error messages it can be difficult to keep track of all components in the model setup To ensure that errors are mini mised we recommend following a clear step by step procedure to develop and run MIKE FLOOD 4 1 Define Model Layout A MIKE FLOOD model is often a compromise between model resolution grid mesh size and computational time required for a simulation Note that computational time is mostly influenced by the total number of wet computational points that occur over an entire simulation This means that a flood simulation with a short duration sharp peaked hydrograph will use much less computational effort compared to a long duration flat peaked flood event Consider this when deciding on grid resolution Other things to consider include e The 1D model extent Ensure that the working area in MIKE 11 MOUSE includes the full 2D extent e The 2D model extent e Where model boundaries will be located remember that often a MIKE FLOOD link is more flexible than applying a boundary condition directly in MIKE 21 e The alignment of the 2D grid this may depend upon the alignment of main chann
57. he tolerance in degrees it will be aligned with the grid MIKE 21 rectangular grid Wetting and Drying Any link can be initially dry or can dry at any time in the simulation If a link is completely dry flow will be added to the dry MIKE 21 cells until cell water depth is above the cutoff flood ing depth Then the cell will become an active wet point Boundaries MIKE FLOOD linkages in MIKE 21 rectangular grid do not necessarily need to be aligned with the MIKE 21 grid This is dif ferent to the restrictions imposed on boundary locations in MIKE 21 Utilise this feature for any MIKE 21 simulation Note that boundaries in MIKE 21 rectangular grid are not allowed to dry out Therefore it is recommended for in land flood plain projects to close all open boundaries in the MIKE 21 bathymetry Hereby all boundaries in the set up will be handled by the 1D models MIKE 21 The default value for land in a MIKE 21 bathymetry is 10 If a flood plain model has bed elevations higher than this ensure that the bathymetry file has this specified MIKE 21 For applications with significant wetting and drying the Smagorinsky eddy viscosity formulation should not be used This means that for the majority of MIKE FLOOD applications a constant eddy viscosity formulation should be applied For overland flow condi tions it is unlikely that eddy viscosity will have a major effect on model predictions friction will dominate However for flow in and around s
58. ible mesh or a rectangular grid is used Rectangular grid Discharge is extracted from the MIKE 11 boundary the first O point and imposed in MIKE 21 in a similar way as a MIKE 21 source discharge The discharge is centred at time step n 1 2 The discharge from MIKE 11 has an impact on the continuity equation as well as the momentum equation in MIKE 21 as with a normal source discharge see MIKE 21 scientific doc umentation MIKE 11 requires a water level boundary from MIKE 21 at time step n 1 in order to step from time step n to n 1 Therefore MIKE 21 will always be one time step ahead of MIKE 11 Thus in order to provide a discharge to MIKE 21 at time step n 1 2 a predictor may be applied in MIKE 11 to estimate the discharge O 12 given the computed discharges O and water levels H at time step n ag aH Q a lo gA 1 Ot e Ox A c gt g where t the time x the length A the cross sectional area C the Chezy resistance number and R the hydraulic radius The gradient in water level is evaluated at the last O point in MIKE 11 The calculated time derivative of discharge is transferred to MIKE 21 together with the discharge at time n in order to predict the discharge at a later time step n 1 2 MIKE FLOOD User Manual 65 Ss Scientific background The predictor assumes that the convective acceleration terms in the last grid point in MIKE 11 are negligible Furthermore
59. iderations e File Layout MIKE FLOOD is designed so that all information relating to MIKE FLOOD is stored in the coupling file The MIKE 11 MOUSE MIKE URBAN and MIKE 21 simulation files are standard which means that the models can be run separately MIKE 11 e Initial Conditions To obtain a stable MIKE FLOOD simulation it is important that the hydraulic conditions are in dynamic equilibrium at Ey the link point This especially important at standard links and structure links For these link types the initial water levels in the MIKE 11 and the MIKE 21 should be the same Alternatively hot start files in the individual setup could be used e MIKE 11 The DELTA coefficient dampens high frequency oscilla tions from a MIKE11 simulation The frequency of the dampened oscillations depends upon the time step and the value of DELTA Note that the time step for a typical MIKE FLOOD application is relatively small which means that increasing DELTA is unlikely to have a signif icant effect upon the accuracy of model predictions Therefore increasing the DELTA parameter is therefore a very useful feature for eliminating minor wobbles and potential instabilities from a simula tion See the MIKE 11 Scientific Documentation for a more detailed description e Additional Options Additional options can be specified in the MIKE 21 parameter file In the couple file the entry M21 Run_Info contains four variables The first is obsolete but is
60. individual cells 28 32 2 Add Remove Layers cocos dl eb ea aes 29 3 2 3 Link river branches to MIKE 21 31 3 2 4 Add Remove Images lt lt o o 32 3 2 5 Block out river cells o o 33 Step by step procedure for blocking out cells in the river bed 35 3 2 6 Link node to MIKE 21 37 3 3 Options for Standard Structure Links 38 3 3 1 MomFact 0 0 0 00 00 0000 eee 38 33 2 EXtRact e uta 0044 ee 6 de eww ee Maw Doe Mace 38 3 3 3 Add Replace Momentum Terms 39 3 3 4 Depth Adjustment o e 40 3 3 5 Activation Depth Minimum and Maximum 40 3 3 6 Exponential Smoothing Factor 40 3 4 Options for Lateral Links 00 41 3 4 1 Side ofRiver darasa radars dari dri 41 A Method 2 02 420202 44084 Ree boo eben Bod eo ee 42 34 3 Structure Type o eee eee 42 SAA SOUE o 2 cine da RG Re Re ERR ae RG EE a a 42 Rectangular Grid cgis eri dd bh od 94 43 Flexible mesh o 43 Noles ee fe oe a as daa ea E aa 43 3 4 5 Depth Tolerance 2 0 000 4 43 3 4 6 Structure Coefficients 44 3 4 7 ExternalFiles 2 00000 44 3 4 8 Additional lateral linkage feature 45 Rectangular Grid ceauP
61. ing to stability in MIKE FLOOD occur in the links themselves and in the wetting and drying in MIKE 21 The numerical solution of both is explicit and the dominant constraint is the time step Another important factor relating to stability is wetting and drying To some extent this can be a model design issue and adjustments can be made to improve stability For example make troublesome link points fully wet if possible or reduce the time step increase the MIKE 21 grid mesh size decreasing the Courant number can minimise the impact of other sources of instability Including a depth dependence to the link which will reduce the flow rate in shallow cells relative to deeper cells within the link may also help The links Standard Urban and Lateral are explicit Meaning that time step considerations become very important The numerical design of the links however means that the local Courant conditions inside the linked cells h points cannot exceed 1 The local Courant number is defined as ame v ved At 6 1 where v velocity g gravity d water depth At time step and Ax grid spacing See the description above in Section 6 1 MIKE 11 pertaining to use of the DELTA coefficient in MIKE 11 to dampen potential instabilities In most cases increasing DELTA to say 0 85 will not adversely affect model predictions 58 MIKE FLOOD Standard Links LAA e Set the momentum factor 0 0 in links where momentum c
62. interrogation 8 2 Lateral Link 1 This is a test to assess the performance of the lateral links and to illustrate their implementation The test represents an inflow channel with over top ping onto a broad flat basin or flood plain as shown MIKE FLOOD User Manual 83 Examples Fixed us Y water levels Figure 8 4 Lateral Link Test 1 Layout An inflow hydrograph discharges into the upstream MIKE 11 river branch Flow spills over the banks of the river channel and into the MIKE 21 basins The left and right basins are separated by land Two down stream MIKE 11 branches are connected to the end of the left and right basins Water level boundary conditions are applied to the downstream branches A closed boundary is applied to the downstream end of the upstream river branch The MIKE 11 network uses a 50 m spacing between h points and the MIKE 21 grid has a spacing of 50 m A simulation time step of 5 s is used The links at the downstream end of the MIKE 21 basin are standard links The main interest in this test however is the lateral links The left bank of the upstream branch chainage 100 m to 1100 m is connected to the MIKE 21 cells in the right basin 7 31 to 7 11 The right bank is con nected to the left basin 5 31 to 5 11 The left and right bank markers of the branch are defined by a sinusoidal curve as shown 84 MIKE FLOOD Lateral Link 1 sex Lett Bank
63. ions are placed according to the chainage not geo ref erenced then the distance from the centre line depends on the location of markers 1 2 and 3 If these markers are not present they are deter mined from the raw data MIKE FLOOD User Manual 69 Ss Scientific background 3 If cross sections are not present at the end points of the user defined reach then extrapolated widths are determined from the existing cross sections 4 Atall digitised points without a cross section the width is interpolated from the existing cross sections 5 The interpolated widths are placed so that they bisect the angle of the two adjoining line segments 6 The levee lines are thus made up by joining the respective left or right end points of the combined interpolated widths and cross sections Cross section Digitised point Interpolated width Levee line lt Figure 7 4 Definition of levee line used for lateral linkage 7 2 2 Definition of lateral linkage lines The linkage tool in MIKE Flood can trace cells intersected by a line The line being one of three types e Center line e Left levee line e Right levee line The only difference between the three is the construction of the line The center line is simply the digitised river from the MIKE 11 set up The left and the right levee lines are constructed based on the cross sectional widths 70 MIKE FLOOD Hydrodynamics Structure Links e When using
64. l and footplates mf cou ple e MIKE 11 separate main channel and flood plain branches intercon nected by link channels mf couple e MIKE 21 both river channel and floodplains modelled in MIKE 21 m2 1a M21 MIKE FLOOD User Manual 97 Ss Examples M11 Branch with M11 Single Branch MF Lateral Links Upstream Flow 7000 10000 Bydrograph ZAN M11 Branch with M11 Link Channels to Floodplain Branches 7000 50 m M21 Grid 50 m with upstream and downstream channels 1 4000 cell width Bathymetry im Above 14 13 14 2000 12 13 11 12 10 11 9 10 8 9 2000 7 8 6 7 5 6 4 5 2000 3 4 1000 2 3 1 2 0 1 Below 3000 Downstream Fixed 0 1000 2000 3000 4000 2 1275 Water Level Figure 8 23 Floodplain Flow Test Layout Each test represents the same geometry consisting of a 50 m wide 5 m deep channel On each side of the channel is a 50 m wide levee Beyond the levees the floodplains are initially 1 m below the levees and rise later ally by 1 m over a distance of 250 m A typical cross section is shown meter m11 t 7000 0000 AS a a iii 400 200 0 200 400 em ross section X data meter Figure 8 24 Floodplain Flow Test Typical Cross section 98 MIKE FLOOD Flood plain Flow Ss The total length is 10000 m The river has a uniform slope of 1 1000 the bed of the main river channel upstream is 10 m and the bed
65. lly uncommon for in channel struc tures river bank overflow can often occur across reasonable distance the levee width and through thick vegetation Rather than estimating a new weir coefficient to account for this specification of a friction term may be a desirable alternative The length of the link used in this calculation is determined from the MIKE 21 cell size for the rectangu lar grid version For the flexible mesh version a weighted distance from the river grid points and the individual linkage segments is used for describing the length e Lateral links can oscillate when the difference in water levels between MIKE 11 and MIKE 21 is similar To avoid this use the Depth Toler ance factor A value of 0 1 meter is recommended e Using the highest HGH structure source type is usually the most con venient method This picks the highest resolution of points MIKE 21 cells or MIKE 11 h points then assigns bed levels using the highest values from the MIKE 21 cells and MIKE 11 points If available exter nal input from a GIS could be used to extract more detailed bank line information e To view the lateral flows in the MIKE 11 results file tick the Lateral Links option in the Additional Output menu of the HD Parameter File HD11 6 5 Structure Links e The structure links are implicit This means that a simulation that uses ES these links will be more stable than the explicit links and simulations i can be performed u
66. m the 1D to the 2D component As a rule of thumb the time scale at which the model changes over should be a factor 40 MIKE FLOOD Options for Lateral Links _ e greater than the time lag caused by the smoothing factor As an estimate for the latter the following expression may be used _ logf a 3 2 where f 0 001 a is the smoothing factor and At is the model time step The estimate is based on the time it takes for an initial deviation in the MIKE 11 and MIKE 21 water level to be reduced to within 0 1 of each other 6 Rerun the model 7 If a small value of the smoothing factor is required you need to satisfy yourself that the results are reasonable and the results for the overall model have not been significantly delayed 3 4 Options for Lateral Links Except for the depth tolerance the options listed in this menu are only rel evant for lateral links pe Structure External Files Link type Sie Method Type Source pepin Toi werc T Friem ruc Geometry omtabte 1 Lateral Right Cellto Cell Weir 1 HGH 0 100 1 838 0 050 z 2 Lateral Left Cellto Cell Weir 1 HGH 0 100 1 838 0 050 3 Lateral Right Cellto Cell Weir 1 HGH 0 100 1 838 0 050 4 Lateral Left Cellto Cell Weir 1 HGH 0 100 1 838 0 050 5 XFLOW 0 6 YFLOWW 0 Ire Structure l 8 Structure l 9 Structure 10 _ Structure Figure 3 20 The overview for lateral links Note that the link type is carried over from the Definition page and cannot be edited
67. n is not applicable Link type Coupling River name M11 Chainage M21 Area Ho of M21 type node ID Ho Cells 1 Lateral HD only river 2457 000 3560 000 1 1 2 Structure HD only culvert 0 000 1 1 3 XFLOWY 0 1 1 4 YFLOWY 0 1 1 5 Standard E HD only tributary 2300 000 C 6 Urban HD only manhole 1 1 Figure 3 4 The overview of links The 6 possible link types are represented Note that for a lateral link two chainages are required whereas for structure and standard links only one chainage is required The XFlow 0 and YFlow 0 do not require any MIKE 11 data since their purpose is purely to block flow in the 2 dimensional grid Finally the Urban link requires a node ID of the manhole 24 MIKE FLOOD Definition sex 3 1 8 MIKE 21 Area Number This option is available for applications with nested MIKE 21 rectangular grids The default value for un nested grids is 1 Thus the M21 Area No must correspond to the identifier in the MIKE 21 parameter file 3 1 9 MIKE 21 Coordinates 310 00 DOD YM Ma Figure 3 5 The list of cells used for a specific link link number 1 The four but tons at the top are used in the same way as the ones described for the link overview section There is a separate table available to enter a list of coordinates defining the MIKE 21 cells The cells are organised in an ordered list The linked cells can be horizontal vertical or any other alignment Remember that if using a lateral link th
68. n on the river levees and improves link stability A value of 0 1 meter is recommended for the depth tolerance When performing initial tests with MIKE 11 with no MIKE FLOOD links do you get the error message Error no 25 At the h point the water depth greater than 4 times max depth This can occur if the bank markers in the cross sections which will be laterally linked to MIKE 21 are low To avoid this message the MIKE11 INI file HD entry WL_EXCEEDANCE_FACTOR should be set to a higher value say 50 Also use a local MIKE11 INI file by copying the file from the installation to the directory where the sim11 file is located Hereby the settings in the MIKE11 INI file only affects the present set up A high resolution of MIKE 11 grid points improves model stability Use the CELLTOCELL method for lateral flows The WEIR1 and WEIR2H types are linked to the MIKE 11 structure routines They include drowned conditions and simulate lateral flows accurately The FORMLOSS method is straightforward If these meth ods are not sufficiently detailed then an external QHTABLE type is available H is considered to be water level either in MIKE11 or MIKE21 Otherwise QDTABLE uses water level structure depth Also if a CELLTOCELL method is applied then Q is flow per unit width 60 MIKE FLOOD Structure Links Ske e Bed friction can be included in the weir calculation see the Scientific Background While this is norma
69. nch and a series of MIKE 21 cells elements e Structure links the link is the connection between the end ofa MIKE 11 branch and a series of MIKE 21 cells same as a standard link However two links are required for each structure link one for each end of the structure These linked links can only be one horizontal and or vertical cell apart e Zero flow links XFLOW 0 and YFLOW 0 the link is a list of cells in MIKE 21 There is no corresponding reference to the MIKE 11 sim ulation e Urban Link the link is the connection between one or more cells in MIKE 21 and a node manhole in MIKE URBAN MOUSE Table 3 1 An overview of the various links of their applicability Link Standard Lateral Structure Zero flow Urban MIKE 11 yes yes yes yes no MOUSE no no no no yes MIKE 21 yes yes yes yes yes Rectangular MIKE 21 yes yes no no yes FM Note that the number of links is not the total number of MIKE 21 cells ele ments connected to the 1D models calculation points To demonstrate the setup shown in Figure 2 1 has five links although each link contains sev eral MIKE 21 cells elements There are two links shown in Figure 2 2 one for the left bank lateral flow and another for the right bank lateral flow Figure 2 3 has two links one upstream of the road and the other down stream of the road The list of links may be re ordered augmented or reduced using the fol lowing tool buttons yn
70. nd display the time series in a separate window Use Ctrl Left click to select more points graphically and display all the time series in a separate window by use Ctrl Double Left mouse click For Urban links MIKE View may be used to display dfs2 result files superimposed on MOUSE results Please refer to the MIKE View manual for how to add dfs2 files in MIKE View Additionally there are the option of displaying grid based results in Google Earth using the flooding plug in Though note that to use these tools the grid results must be geo referenced i e not NON UTM 5 1 Google Earth plug in To use this plug in Google Earth must be installed http earth google com Once this has been installed the DHI plug in may be installed from the installation DVD To visualize inundation in Google Earth the following procedure should be followed 1 Start the Google Earth plug in by selecting Start gt Programs gt DHI Software gt Google Earth Flooding 2 Within Google Earth go to the options menu which may be found under Tools gt Options Click on the preferences tab and deselect the field Show web results in external browser 3 In the left overview window under places there is a menu item termed new floodmap Within this menu item a Load dfs2 file hyperlink is present select this 4 Browse for the dfs2 to be used Note that the dfs2 file must be geo ref erenced otherwise the file cannot be placed correc
71. nested grids provided a nested MIKE 21 is available the selection tool may export multiple files for the same river reach i e a selection file for each grid in the MIKE 21 set up To distinguish between these different selection files MIKE FLOOD inserts the area number at the end of the file name e g if the file name selection dfs2 is chosen the actual selection files are named selection 1 dfs2 selection 2 dfs2 etc depending on the number of nested grids in the MIKE 21 set up MIKE FLOOD The graphical layout e Step by step procedure for blocking out cells in the river bed 1 In the MIKE FLOOD graphical view right click and select the Block out river cells option see Figure 3 15 13000 12000 11000 10000 9000 8000 7000 Zoom Out 6000 Previous Zoom Next Zoom 5000 Pan shift 4000 Grid Copy to Clipboard 3000 Save to Metafile Save to Bitmap 2000 Add Remove Layers 1000 Properties Link branch to MIKE 21 D Add Remove Images 1000 2000 ll 2000 D 2000 4000 6000 8000 10000 Figure 3 15 Accessing the blockage tool in MIKE Flood 2 In the dialog that appears select the river reach that the blockage is to be applied to Please ensure that the river name is typed correctly and that the correct topo ID is also supplied If chainages are given which are beyond the river reach the values are modified to coincide with the reach ends Also supply the name to be used fo
72. o Bitmap 8127200 Add Remove Layers Properties Link branch to MIKE 21 8127000 3 E Add Remove Images i A Block out river cells 8126800 4 Link node to MIKE 21 372000 372500 373000 373500 374000 Figure 3 7 The graphical layout of MIKE FLOOD Note the drop down list that may be accessed by right clicking The figure illustrates the use of a rectangular grid version of MIKE 21 8128200 8128000 Zoom Out Previous Zoom Next Zoom Pan Shift 8127800 4 8127600 Grid 8127400 J Copy to Clipboard Save to Metafile Save to Bitmap 8127200 4 8127000 Add Remove Layers ne b Properties 372000 372500 373000 Link branch to MIKE 21 Add Remove Images Block out river cells Link node to MIKE 21 Figure 3 8 The graphical layout of MIKE FLOOD The figure illustrates the use of a flexible mesh version of MIKE 21 The Block out river cells does not apply to a flexible mesh MIKE FLOOD User Manual 27 1 Application details 3 2 1 Right clicking on the graphical view of MIKE FLOOD displays a number of options The following options are available through the graphical view e Itis possible to zoom in and out in the graphical view To return to the full view right click and choose Zoom extents Note that the extent of the graphical view is governed by the last selected file either MIKE 21 MOUSE or MIKE
73. o Flow Links X or Y M21 Cells k 15 20 25 30 M21 Cells j Figure 8 29 Floodplain Demonstration Diagram of MIKE FLOOD Links The upstream discharge hydrographs for the river and tributary and the downstream water level boundary condition which is tidal are shown below _Upstream Discharge Tide Prediction oo x mo x ao cade x 000 1200 naaa es t i 4 4 YE Let al pe 2 pr a me o om aa e ae SS a man Figure 8 30 Floodplain Demonstration Boundary Conditions Model results showing water surface contours and velocity vectors near the peak of the flood event are presented in Figure 40 The time series 102 MIKE FLOOD Floodplain Demonstration plots in Figure 8 32 show water levels immediately upstream and down stream of the road embankment and water level difference across the road embankment Also shown is discharge through the main river channel and through each culvert The model results show that for this particular flood event there is a peak 0 36 m head drop across the road embankment However the peak head drop at the peak of the flood is 0 16 m Peak discharge through the main river channel is 44 2 m3 s which is much higher than the culvert flows of 1 7 m3 s and 3 8 m3 s If this model was intended to investigate the hydraulic impacts of the road embankment a model of the existing situation no road could also be per formed Comparing mod
74. o a sinusoidal variation of range 0 10 m MIKE FLOOD User Manual 81 Examples The basin is described using MIKE FLOOD 4 km is described in MIKE 11 and 4 km is described in MIKE 21 In both models the longitudinal grid spacing is 100 m MIKE FLOOD simulates the transfer of mass as well as momentum between the 1D MIKE 11 model and the 2D MIKE 21 model The water level at different times after start of the simulation is depicted below sez m e MRE 1 pat mee MET MEE 2 m wr meres Sth gw ae Test Standing Vine Test Standing Wave Test o Dis ler on OWnis0 1453200 Figure 8 2 Standing Wave Test Results Water Level Profiles The files required to setup and run this example are available These files take this example further than presented here with tests using e the standard link type e a 10 cell 1000 m wide setup of the same test case e a MIKE 11 model of the entire test no MIKE FLOOD link and e a MIKE 21 model of the entire test no MIKE FLOOD link Thus four separate tests are included in this single MIKE FLOOD setup The results are shown as water level profiles at various time steps 82 MIKE FLOOD Lateral Link 1 LEA Dawes r Figure 8 3 Standing Wave Test Results Water Level Profiles 2 While it is difficult to examine the individual curves the plots shown above demonstrate that the various link types are performing satisfacto rily See the examples provided for further
75. omposer and Data Viewer MIKE 21 and MIKE VIEW MIKE 11 MOUSE MIKE URBAN Also MIKE ZERO allows MIKE 21 result files to be exported to an ARC GIS ASCII input file The recommended tool to use for MIKE 11 MIKE 21 rectangular grid couplings is the Result Viewer which is activated from MIKE ZERO File New Result Viewer The viewer can present 1D 2D and 3D results from different DHI Software models at the same time including res11 result files from MIKE 11 and dfs2 results files from MIKE 21 rectangular grid e New files are added to the Result Viewer project by using Result Viewer Projects Add files to project and press the new page icon to the right The File Type is a scroll down menu where the result file is chosen e The work area is defined under Result Viewer Projects Work Area e Inorder to display the results together the two models need to be based on the same geo reference Thus the MIKE 11 network must be described in the same UTM metric grid as the MIKE 21 bathymetry file MIKE FLOOD User Manual 51 Ss Pre and post processing e The type of result data to display contours and or vectors is selected in Result Viewer Projects Active View Settings On line animation as well as production of videos can be done Time series can be extracted by using the time series button at the upper tool bar to the right Use double click on the left mouse button to select a point graphically a
76. onservation is unlikely to be important e For lateral links try to make the structure resolution the same as or finer than the MIKE 11 Ax and the MIKE 21 grid size e If modelling a simple structure between adjacent MIKE 21 cells use the implicit structure link This link type is significantly more stable than a standard link e Stability in a link is improved if flow is continuous in one direction only through the link for example cascading flow over a weir Try to utilize this when building the model by selecting link locations where backwater effects are less significant e Other adjustments such as increasing friction and or eddy viscosity can be used to improve stability However such adjustments can com promise model performance 6 3 Standard Links e The end of branches in MIKE 11 that connect to MIKE 21 must have a water level boundary specified This is a dummy boundary specifica tion for initialisation purposes and will not affect the MIKE FLOOD simulation e Link points in MIKE21 can be dry initially and can wet or dry during a simulation e MIKE 21 rectangular grid only A predictor extrapolation factor is applied for obtaining proper time centring of the values that are exchanged between MIKE 11 and MIKE 21 rectangular grid The pre dictor assumes that the flow between the last two cross sections in MIKE 11 before the coupling is based on normal bed resistance flow i e no structures If there is a
77. or link direction 0 MIKE FLOOD User Manual 71 Scientific background and conversion from discharge O to flux q Q A A 2D cell size For the momentum equation in the x direction n 1 n l n amahy byad emah dyn 7 2 A yy Cos O E 7 3 Bra bmi 7 4 Cry COSO Cmi ES 7 5 d 6 dim A 7 6 If the terms are added for example if the structure link represents a struc ture flowing under the existing MIKE 21 topography further adjustments are made to ensure consistency between the MIKE 11 and MIKE 21 terms Again for the x direction ls its a dy 7 7 dun am Sara 7 8 bmi bmn 7 9 cim eun I 7 10 dat dun A 7 11 The same adjustments apply for the y direction momentum equation except a sine direction adjustment is made rather than a cosine adjustment Note that the implicit terms from MIKE 11 used are from the MIKE 11 solution at the previous time step In most applications where flow condi 72 MIKE FLOOD Hydrodynamics Structure Links LA tions vary quite slowly relative to the time step this is not a problem It may become a problem if rapid and relevant changes do occur over a time step Also the displayed value of flow in the q point of the MIKE 11 branch may not necessarily be the flow through the MIKE 21 cell It is recommended that the MIKE 21 results are interrogated in this case rather than the MIKE 11 results 7 3 1 Hydrodynamics Exponenti
78. pace delimited Line 2 List of nc values of downstream levels m space delimited Line 3 onwards nr lines List of nc values of upstream level then nc values of discharge m s space delimited Notes e If QHTABLE levels are water level m e If QDTABLE levels are water depth m e If CELLTOCELL discharge is flow per unit width m2 s Note that values are space delimited 348 Additional lateral linkage feature MIKE FLOOD includes a feature for analysing the invert levels of lateral links The feature works by generating an ASCII file containing the invert levels of the lateral links This file may be directly imported into the cross section editor Internally within MIKE FLOOD lateral links are treated differently depending on whether a rectangular grid or a flexible mesh is used Rectangular Grid When using the rectangular grid lateral links are treated in the following way e The h grid points within the linked river reach are identified e The linked MIKE 21 cells are given a chainage based on the cell size That is the chainage runs from cell centre to cell centre plus additional contributions from the first and the last cell The MIKE 21 chainages are subsequently normalised so that they span the lateral links chain age MIKE FLOOD User Manual Ss Application details e Depending on the method used the lateral structures will be set up according to the 2D cells or the rive
79. r grid points The chainage of the structures will be based on the chainages in the river The chainage of the structures are normalised so that the span the same as the river chainage The code uses the location based on these nor malised chainages to locate which cells and h points match up with which lateral structure Flexible Mesh MIKE FLOOD with a flexible mesh treats the lateral links in the follow ing way The h grid points within the linked river reach are identified The linked MIKE 21 elements are given a chainages based on the seg ment chainage values Each segment constitutes an internal lateral structure modelled as a weir Depending on the method used the lateral structures will be set up according to the 2D topography or the river grid points The chainage of the structures will be based on the chainages of the segments Generating the ASCII file with the invert levels To generate this ASCII file the following procedure should be followed Set up the MIKE Flood model Place an empty file named MF Lateral txt in the same folder as where the sim11 file is located Run MIKE Flood The ASCII file is exported in the first time step of the run Once the first time step of the simulation has been completed the file in step 2 will have been overridden with values describing the inverts of the lat eral links Open a new cross section file xns11 and import the MFLateral txt using File gt Import g
80. r the selection file including the dfs2 extension see Figure 3 16 MIKE FLOOD User Manual 35 e Application details Block out river cells Selection file selection dfs2 Ah Cancel Link info River name salmon Chainage upstream 100000 Topo ID 2003 Chainage downstream 124000 Figure 3 16 The dialog box for selecting which cells to block out in the MIKE 21 bathymetry 3 Open the bathymetry file used in the MIKE 21 set up The file may be accessed through the file gt open menu of MIKE Zero or through the MIKE 21 interface by clicking the view button found in the bathyme try menu The latter automatically opens the bathymetry file in the grid editor 4 With the bathymetry file as the active window in MIKE Zero it is pos sible to access the menu Tools gt Load Selection found in the main menu bar of MIKE Zero At this point you are prompted for the selec tion file Browse for the selection file previously generated remember ing that the file name has been augmented with a number indicating the area number The selected cells will by now be highlighted in the grid editor 5 Access the set value through the Tools menu of the main MIKE Zero tool bar and provide the land value of the dfs2 file in the active box see Figure 3 17 6 Save the bathymetry file under a different name to ensure that the orig inal data is not overridden 7 Inthe MIKE 21 editors bathymetr
81. relating to the links will occur Do not be surprised if several adjustments of the links need to be made at this stage or that the time step required is much shorter than you expected Check some of the tips available in this document see Tips and Trouble shooting Once an initial MIKE FLOOD simulation has been completed the model ler should have a good appreciation of the model layout and its various components and be aware of the potential problems that may crop up in subsequent simulations and analyses 50 MIKE FLOOD Run MIKE FLOOD Simulation ae 5 PRE AND POST PROCESSING It is envisaged that much of the pre and post processing of MIKE FLOOD will be done in a GIS The GIS provides superior tools for the management and storage of large amounts of data which is required for many flood plain applications However many GIS do not have special ised tools suitable for modelling time series analysis grid editing surface interpolation etc so MIKE ZERO has its place in the modelling method Standard spread sheets EXCEL are also useful for data management Links to external programs are available at present through MIKE ZERO Linkage properties can be imported into MIKE FLOOD either through an external ASCII file XYZ files from a GIS or by cutting and pasting into the MIKE FLOOD interface The results from MIKE FLOOD water levels discharges fluxes AD components etc can be viewed using the Result Viewer Plot C
82. rily the upstream chainage in the branch it may well be the downstream chainage the label US refers to lateral link specifications only The same boundary location should exist in the MIKE 11 boundary file bnd11 and be defined as a water level boundary in the initial MIKE 11 set up This boundary condition specification is only to maintain consistency between MIKE FLOOD and MIKE 11 it will be overridden by infor mation from the link during simulation Furthermore if performing an AD simulation then an open concentration boundary should be speci fied not the Time Series dependent option e fusing a lateral link M11 river name is the MIKE 11 branch with the link US M11 chainage and DS M11 chainage define the upper and lower extents of the lateral link so all MIKE 11 calculation points between the specified chainages will be linked to MIKE 21 Unlike the standard links no further adjustments need to be made to the MIKE 11 boundary definitions Please note that the lateral link must span a reach in the river which includes at least one grid point typically a cross sec tion e For zero flow links no MIKE 11 information is required e For urban links an urban ID is required This urban ID depends on the type of urban link That is if the link is to an inlet or an outlet the node ID must be supplied For a link to a pump the urban ID constitutes the pump ID and a for a link to a weir the weir ID is needed The chainage colum
83. set up shown uti lizes a rectangular grid 3 1 1 MIKE 21 File Name A complete MIKE 21 setup should be established and tested prior to set ting up MIKE FLOOD The MIKE 21 setup is defined in the usual way using the respective editor The path and file name of the resulting MIKE 21 File Name m21 or m21fm is provided in this menu Note that the MIKE 21 engine is selected through the selection of the file type C work main Praducts S ource E xample MFlood FloadplainD emonstration m21 big M21 m Figure 3 2 MIKE 21 path name along with browse and edit buttons A button allows for browsing the parameter file Furthermore the Edit MIKE 21 input button allows for opening the existing MIKE 21 parame ter file for further editing 20 MIKE FLOOD Definition eo 3 1 2 MIKE 11 File Name It is optional whether a MIKE 11 model is to be used with MIKE FLOOD If a link is to be established the tick box to the left of the file name field should be activated Ifa MIKE 11 set up is to be used with MIKE FLOOD the complete MIKE 11 setup should be established and tested As with MIKE 21 this is done in the usual way using the appropriate editors The path and file name of the MIKE 11 File Name sim11 is provided in this menu C AAdata MIKEFlood vived sim11 a Edit MIKE 11 input Figure 3 3 MIKE 11 simulation file path name along with browse and edit but tons Note the tick box on the left which may be used to select or deselect
84. simulation files do not contain any information relating spe cifically to the links except for e A dummy water level boundary condition must be applied at each standard or implicit link point in MIKE 11 The coupling file interface is arranged with 4 sub menus e Definition e Standard Structure Link Options e Lateral Link Options e Urban Link Options Each of the sub menus are described below 3 1 Definition The Definition menu contains information on the simulation files used in MIKE FLOOD and the general linkage definitions MIKE FLOOD User Manual 19 y Application details mfbig couple laa MIKE Flood Y Delintion C work main Producte exampie t4FloadF locdalair Demonziation m21big M21 m Stendord Strucie f C SwarkimanhProducishexamplesM Food F bodpleinDemonstiatorim lag am Lu sumiso 11 ireu LeteralLink Opbons Urban Link Options O di MIKE URBAN nlx o X 6 y EAT 3 24 3 a 160 000 3237000 1 23 4 HD ony RIVER 1650 030 5237000 1 22 5 a Laters HD oriy TRB 1350 00 1885000 1 19 23 8 HD only TB 1350 030 1585000 1 17 23 7 5 prona i T 1 EJ 22 gg 11 E 21 gi 20 8 20 9 21 10 21 1 20 12 18 12 18 12 7 13 18 14 15 15 14 15 13 16 13 17 12 17 n iv i016 w 15 10 i 2 E 14 rra l 371000 372000 374000 375000 la MIA gt walidation A Simulation A MIKE 11 Execution Log Figure 3 1 Definition page of the MIKE FLOOD Editor The
85. sing longer time steps a e In the structure links MIKE 11 lags one time step behind MIKE 21 Thus the displayed value of flow in the q point of the MIKE 11 branch may not necessarily be the flow through the MIKE 21 cell It is recom mended that for structure links the MIKE 21 results be interrogated rather than the MIKE 11 results e The direction of the flow is derived from comparison of the orientation of the MIKE 21 grid and the direction of the MIKE 11 branch A pro jection is made of the flow equation onto the grid cell faces MIKE FLOOD User Manual 61 a os Tips and troubleshooting e The MIKE 21 cells that define the inlet and outlet of the structure link must be adjacent to each other Thus if the inlet cell is J K then the outlet cell must satisfy at least one of the equations 6 2 However more than one MIKE 21 cell can be specified and a list of cells can be in any direction or alignment K K 1 K K 1 62 e The river branch that defines the structure link can only be a 3 point branch one h point at the inlet one h point at the outlet and one q point connecting them The q point can have as many parallel struc tures as are needed or can have no structures it can simply be a cross section e There is an option to add or replace momentum terms If the momen tum terms are replaced the flow conditions calculated in MIKE 11 override flow conditions in the MIKE 21 cell If the momentum terms
86. t Import raw data The ASCII file has three entries for each lateral link given by M11 chainage invert M21 chainage invert Struck chainage invert 46 MIKE FLOOD Options for Urban links _ AS 3 5 3 5 1 3 5 2 3 5 3 The inverts of each of the links may now be investigated for possible inconsistencies Options for Urban links Type There are a number of options available for an urban coupling each described below There are four different types of links available e M21 to inlet A link between the overland and a manhole in MOUSE The urban ID is the node ID in this case e M21 to outlet A link to an outlet in MOUSE The urban ID is the node ID in this case e Weir to M21 A link between a MOUSE weir discharging out of the sewer storm water system e Pump to M21 A link between a MOUSE pump discharging out of the sewer storm water system and the MIKE 21 topography The links may be to multiple cells in the MIKE 21 rectangular grid or alternatively an area in the flexible mesh If the latter is used at least 3 points must be supplied to constitute an area polygon If only one point is supplied in a given urban link then the discharge is introduced as a source sink Inlet method Max flow The exchange of water may be described through 3 different methods e Orifice equation The flow between MOUSE and MIKE 21 is gov erned by a standard orifice equation e Weir equation The
87. terpolated from the MIKE 21 cells and the MIKE 11 A points to the specific internal structure locations MIKE FLOOD User Manual 67 Scientific background Linked M21 Lateral Linked M11 cells Structure h points p gt Ta Je as Sy i gt 5 Interpolated levels can overlap but v 4 distance dependence minimises inconsistencies DON gt HR 1 RA 0 a L Water levels to structure interpolated from relative locations of M11 h points M21 cells and internal 0 structures Interpolation is distance dependent Figure 7 2 Lateral Link Interpolation of Water Levels Using the calculated width and bed level and interpolated water levels the flow across each internal structure is calculated using a standard structure equation These structure equations are the same equations used in MIKE 11 The flow from each internal structure is then distributed to from the MIKE 11 h points and MIKE 21 cells This is done by determining the range of influence that each internal structure has upon each linked MIKE 11 h point and MIKE 21 cell As shown in Figure 7 3 if MIKE 11 points lie within the range of influence of a given internal structure flow is dis tributed across those points according to water depths in each point If no MIKE 11 h points lie within the range of influence flow is distributed to the nearest upstream and downstream points using a distance dependent interpolation The same applies for MIKE
88. the default Flexible mesh For the flexible mesh the lateral link is divided up into segments Each segment being defined by two consecutive set of coordinates for the lat eral link A discharge is evaluated across each segment and distributed in MIKE 11 according to the chainage values for the segment end points The source parameter only controls the from where the levee height should be extracted e MII The levee height is determined from the bank markers in MIKE 11 e M21 The levee height is defined by the topography in MIKE 21 e HGH Takes the max of the MIKE 21 topography and the MIKE 11 bank markers e EXT The levee height is supplied in an external ASCII file The HGH source type is the default Note The levee height is not allowed to be below the MIKE 21 topography at the linkage point nor below the bed level in MIKE 11 Thus if the selec tion is such that this occurs MIKE FLOOD will use the limiting value 3 4 5 Depth Tolerance This parameter is used to smooth out the transition when the flow over the lateral link changes direction The parameter is also available for the implicit structures In this case the parameter is used to describe the water MIKE FLOOD User Manual 43 Application details level difference across the structure at which point the discharge gradients are gradually suppressed If such a suppression is not applied the model may experience numerical instability The suppression varies
89. the use of the two arrow buttons in the upper right hand corner 3 2 3 Link river branches to MIKE 21 The MIKE FLOOD interface has tools for the automatic selection of link age to MIKE 21 Two main linkage types are available e Lateral links e Standard structure links The lateral link requires the user to supply the river branch name and the topo ID used along with the reach stations The user also selects whether the linkage should be along the centerline or the line made out by the left and right levee Based on the information entered by the user the tool auto matically selects either e the MIKE 21 grid cells intersected by the left right or centre line for the rectangular grid version e or in the case of the flexible mesh the coordinates of the left and the right end points of the cross sections MIKE FLOOD User Manual 31 Application details 3 2 4 The standard structure link only requires the user to specify the branch name the topo ID and whether the link is to be applied at the upstream lowest chainage or the downstream end greatest chainage Once the links have been established the location of the links may be inspected by stepping through the links in the cell table on the left whereby the active cell point is highlighted in the graphical view Link branch to MIKE 21 Link type ox Lateral link Left y Lx Cancel Standard or structure link e C Link info River name river Topo
90. tly on the globe 5 Click on the Get statistics button A dialog will appear asking whether an ActiveX component may be launched Please select yes 6 The next menu will prompt the user as to whether the images from the dfs2 file are to be generated Please answer yes unless the images have already been created previously by having used the tool on this particular file before 52 MIKE FLOOD Google Earth plug in 7 Another ActiveX window will prompt the user Please select yes to this query 8 A final message box will appear once the images have been created and loaded 9 Once the file has been loaded and the corresponding images overlays created the web viewer should look like figure Figure 5 1 CUUC UD 29 1 UU UU 2002 05 23 12 30 00 2002 05 23 13 00 00 2002 05 23 13 30 00 2002 05 23 14 00 00 2002 05 23 14 30 00 MMS H_Water_Depth_m A 2002 05 23 00 00 00 E Start Stop Figure 5 1 The Google Earth plug in for viewing 2D rectangular grid results as overlays 10 Various items may be displayed though note that the legend does not graduate the values Thus if a cell is flooded it will be activated in the corresponding image 11 To animate the inundation select a specific time step and click the start button MIKE FLOOD User Manual 53 Pre and post processing 54 MIKE FLOOD General Considerations _ Ae 6 TIPS AND TROUBLESHOOTING 6 1 General Cons
91. tructures the value of eddy viscosity can have a significant effect upon predictions Caution is advised in such cases MIKE 21 flexible mesh The MIKE FLOOD run time will be impacted by the mesh size Thus it is advantageous to spend some time initially in generating a sound mesh which represents the major features of the topography without resorting to very small elements 56 MIKE FLOOD General Considerations Ss When using the flexible mesh the code will locate the nearest mesh ele ment face and apply the discharge exchange along this face Therefore it is beneficial to integrate the linkage lines into the mesh The latter may be done using the additional feature for exporting the linkage lines The flexible mesh couples along lines in the model The discharge is distributed along these lines and it is therefore of outmost importance that these coupling lines are completely contained within the mesh Ideally the lines should be integrated in the mesh The flooding wetting and drying values should be decreased from the default values A reduction of a factor in the order of 50 is recom mended The flexible mesh version of MIKE FLOOD uses an adaptive time step for the overland flow 2D Information is exchanged at every overall time step controlled by MIKE 21 The 1D models use the time step defined in the MIKE 21 set up Thus the time step should be selected based on considerations of the 1D models MOUSE and MIKE 11
92. with one or more cells ele ments in MIKE 21 Below follows a description of each of these link types Standard Link f Na A MIL a This is the standard linkage in MIKE FLOOD where one or more MIKE 21 cells elements are linked to the end ofa MIKE 11 branch This type of link is useful for connecting a detailed MIKE 21 grid mesh into a broader MIKE 11 network or to connect an internal structure with an extent of more than a grid cell or feature inside a MIKE 21 grid mesh The link is explicit see the scientific documentation for a full description Potential applications are shown Standard Link Connecting a detailed Mii structure within a M21 grid m Network a VA celeste SE A Standard Link Connecting a broad Mii network to a detailed 142 FRE x A gt Figure 2 1 Application of Standard Links Lateral Link A lateral link allows a string of MIKE 21 cells elements to be laterally linked to a given reach in MIKE 11 either a section of a branch or an entire branch Flow through the lateral link is calculated using a structure equation or a QH table This type of link is particularly useful for simulat MIKE FLOOD User Manual 15 Ss General description ing overflow from a river channel onto a flood plain An example is shown Specify flow over either left or 4 TAE O A we Wy Ft o Lateral Link Lateral weir flow from river channel 1411 to floodplain
93. xamples presented below are designed to test the operation of the features of MIKE FLOOD and to demonstrate the use of these features Most are available with the DHI software in the Examples folder Other wise check www dhisoftware com where the input files can be down loaded Various MIKE ZERO tools can be used to view the results including the Result Viewer MIKE VIEW not in MIKE ZERO Plot Composer and the time series profile series and grid series editors A brief outline of the examples is provided e Standing Wave examines momentum transfer through standard links e Lateral Link 1 investigates lateral link flow over a bank of varying bed levels and includes an AD component e Lateral Link 1 investigates lateral link flow and compares results to a standard MIKE 11 weir e Flow Direction examines flow directions through various links e Flood plain Flow examines the transition from in bank to flood plain flow in a simplified setup e Floodplain Demonstration demonstration of a real flood plain applica tion The example is available both for the rectangular case as well as the flexible mesh version 8 1 Standing Wave Consider an 8 km long basin closed at both ends MIKE 11 Branch MIKE 21 Basin Figure 8 1 Standing Wave Test Layout The width of the basin is 100 m and the mean water depth is 2 0 m The bed resistance is C 50 m1 2 s An initial disturbance of the water surface is imposed corresponding t
94. y menu select the new edited bathymetry 8 Repeat the procedure for all rivers requiring blocking out of cells 36 MIKE FLOOD The graphical layout e G Set Value Set Value Sub Set Set value 0 Add value Multiply value Cancel Help Figure 3 17 The set value dialog Choose the appropriate land value for the dfs2 file 3 2 6 Link node to MIKE 21 Manholes may be linked to MIKE 21 through the use of this tool The tool can automate the linking of all manholes to the MIKE 21 grid mesh or the user may select individual manholes to link based on either a drop down list or a node selection file nse a Link node to MIKE 21 Link info Node ID E 3 O Node selection file O All Nodes Figure 3 18 The link node menu The user can either link all manholes in the set up ora selection hereof by the use of either a node selection file or through the drop down list of node IDs MIKE FLOOD User Manual 37 Ss Application details 3 3 3 3 1 3 3 2 Options for Standard Structure Links Mom Fact Ext Fact The options listed here are only applicable for Standard and Structure links Implicit relaxation factor AddReplace Depth Activation Activation Link type Depth min Depth max Lateral Lateral Lateral Lateral XFLOWY 0 0 000 0 000 YFLOW 0 0 000 0 000 Structure l

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