EFH2 Computer Program, Estimating Runoff and Peak Discharge
Contents
1. Opens a standard Windows dialog window which allows the user to open an existing file Recalculate Forces a recalculation of the output data While the program automatically recalculates with each change in a data field it does not recalculate upon opening an existing file allowing the user to observe the data in an existing file without change Save Ctrl S Saves the current data to a file for later retrieval and editing An EFM extension is added to the file name identifying the file as EFH2 data Print Ctrl P Prints the current data to the default Windows printer A dialog window opens allowing the user to change the selected printer and select desired printer parameters Page one with basic data and discharge information will always print Page two with runoff curve number calculations will only print if runoff curve number data has been entered or exists within an existing file Exit Terminates the application Table 6 Menu File Description EFH2 User s Manual August 2009 Printing to a file is possible However with most printer drivers many unwanted characters will be embedded in the printed file By choosing a generic text printer and selecting the print to file check box an acceptable facsimile of the printout can be sent to a text file An appropriate print driver is required to take advantage of this option Menu Edit EFH 2 Estimating Runoff and Peak Discharge Cut Ctrl Copy Ctrl C Paste lt2. WA AA AAA AAA A id 17 RENTADO 18 O ede 2l EFH Rilercnce GIO e O Senter Cero RG 1 Example PropleM A eo A 1 e A O B 1 Example Problem C ia AA A cas C 1 Errors amp O O e ere nen Saree eres D 1 EFH2 User s Manual August 2009 List of Figures Figure 1 Welcome to EFH2 for Windows WINdOW oooooooooooccccccnnnononononononononnnnnnnnnnnnnnnnnnnnnnnnonnnnnnnnnnnnannnnnnnnnnnnss 6 rn Inia oduc uord AAA yen aE ar Gane take Ao tached nubteuahat T A a a Goaeen 6 Figure 3 7 EFA Mena Ds iatate nc again et te O etn aa hie Ute etn teeta 7 Bre 4 Meni le citan oliendo olaa iaa E E 7 Fisure S Mende 8 Ficure o Menu Vie ueser cated iii ide 8 Figure 7 Mona Tool E IAS A eee Made eee eae 9 TSU ee Monu Hel Puri A Ad 9 Figure 9 HelpContents Dialos Wind OWN RA 10 Figure 10 Help About Dialog WM eds 10 Broure UL Toba E Ue 11 Risure 12 Basie Cate ta ora lidia dica aii 11 Fisure 13 State Held Entry Error Messa ota ii 12 Figure 14 Rainfall data file not found warning message cccccccccncncnnnononononnnonnnnnnnnnnnnnnnnnonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnos 12 Figure 15 Average Slope Calculator Dialog Window ccccccscceeeeeeeeeeeeeeeeeeeeeeeeeeesssssssesssssssessssseseseeees 14 Figure 16 Average Slope Calculator Warning Message for drainage area entry greater than 2 000 acres 15 Fisure 17 Ramitall Disehiar ce data A asa Ebo 16 Figure 18 Approximate geographic boundaries for NRCS rainfall distributions oooonnnnnnnnnnnnnnnnnn
3. Ctri Figure 5 Menu Edit Menu Item Dropdown Choice Explanation Edit Cut Ctrl X Used to cut selected highlighted data from an entry field and move it to another field Copy CtrlC Used to copy selected highlighted data from an entry field Paste Ctrl V Used to paste or insert copied data to the current cursor position in a field Data highlighted during the execution of this command will be replaced with the pasted data Table 7 Menu Edit Description Menu View EFH 2 Estimating Runoff and Peak Discharge File Edit AVE Tools Help Figure 6 Menu View Menu Item Dropdown Choice Explanation View Toolbar Used to show or hide the Toolbar on the main program window Table 8 Menu View Description EFH2 User s Manual August 2009 Menu Tools EFH 2 Estimating Runoff and Peak Discharge Fie Edit View BEAS Help Average Slope Calculator Hydrologic Soil Groups Figure 7 Menu Tools Menu Item Dropdown Choice Explanation Tools Average Slope Opens the Average Slope Calculator dialog window See Time Calculator of concentration data and computations section for information on the Average Slope Calculator dialog window Hydrologic Soil Opens the Search for Hydrologic Soil Group window See Groups discussion of the Hydrologic Soil Group window under the RCN Tab section Table 9 Menu Tools Description Menu Help EFH 2 Estimating Runoff and Peak Discharge File Edit view Tools Figure 8 Menu Help Menu Item Dropdow
4. Practice Waterway Field 2 Bw lhEm Date 379 2009 Drainage rea Aunoft Curve Number Watershed Length feet Watershed Slope percent Time of Concentration hours Figure 3A Basic Data tab Example A EFH2 User s Manual August 2009 Step 2 RCN tab Click on the RCN tab and enter the appropriate soil cover complex and area information in order to calculate the runoff curve number for the watershed Upon completion of data entry the RCN tab should appear as shown in Figure 4A EFH 2 Estimating Runoff and Peak Discharge File Edit View Tools Help al S ajaj gt 2 C Urban Area Developing Urban Cultivated Agriculture Other Agriculture Arid Rangeland COVER DESCRIPTION CULTIVATED AGRICULTURAL LANDS Fallow Bare soil e Crop residue CR poor Crop residue CR good Straight row SR poor Straight row SR good SR Crop residue poor SR Crop residue good Contoured C poor Contoured C good C Crop residue poor C Crop residue good Cont amp terraced C amp T poor Cont amp terraced C amp T good C amp T Crop residue poor C amp T Crop residue good Straight row SR poor Straight row SR good SA Crop residue poor SA Crop residue good Contoured C poor Panteaurad IMI nana Acres Weighted Curve Number 78 Percentage Accumulated Area ac 90 00 Figure 4A RCN tab Example A When data entry is complete click Accept to automatically return to the Bas
5. The dropdown list must be displayed to select a match Pressing ENTER will accept that match If the full county name is typed it must match one from the file or no data will be displayed See the discussion under Optional files COUNTY XX for more information on development and use of the COUNTY XX file Practice field The Practice field is an optional data field and may be used to enter additional project identification information By field In the By field the user may enter information identifying themselves Date field For new files the Date field 1s automatically populated using date information from the computer s system files For opened files the date on which the file was saved is displayed Modifying saved files will not update the Date field If the user wishes to update the displayed date he or she must enter the appropriate date and save the file 12 EFH2 User s Manual August 2009 Watershed Data Drainage Area field Drainage Area may be entered directly in this field or brought over from the Average Slope Calculator window or the RCN tab if either of those are used with the most recent entry prevailing For example if the user enters 55 acres on the Average Slope Calculator window but then computes runoff curve number using the RCN tab and enters data for 60 acres the Drainage Area field on the Basic Data tab will display 60 acres If the user calculates area with the RCN tab it will display on the basic data s
6. a Time of Concentration greater than 0 1 hours and continue Time of Concentration gt 10 compute aborted Correct Time of Concentration to be equal to or less than 10 hours Total land use area exceeds 100 percent Must correct to exit cell While using the percentage option on the RCN tab the user has made entries that when added together exceed 100 percent Correct the entries to total 100 percent Total land use area exceeds 2000 acres Must correct to exit cell Reduce the land use area to 2000 acres or less and continue Type rf file is corrupt Correct before running EFH2 program Correct the type file before running the program Unable to display Help Contents There is no Help associated with this project Check that the file EFH2 chm is present in the directory where the EFH2 exe file resides If not download it or request your IT contact to download it Watershed length must be in the range 200 to 26000 feet Correct the watershed length value to be within this range and continue Watershed slope is less than 0 5 percent Results may not be valid Although the user may run the program with slopes less than 0 5 percent the results should be thoroughly checked for validity EFH2 User s Manual August 2009 Watershed slope must be less than 64 percent Correct the watershed slope to be less than 64 percent and continue Watershed slope should be more than 0 5 percent but must be more than 0 1 perc
7. drainage area and runoff curve number carried over from RCN tab EXAMPlO De ic pesos B 6 Figure 8B Basic Data tab showing time of concentration data calculated from user input watershed length and SLO Pe Example Dll clica B 7 Figure 9B Blank Rainfall Discharge data tab Example B ccccccssseeeccceeeeeeeeeaeeaeseeesseseeeeeeeeeeeeeeeeaaas B 8 Figure 10B Rainfall Discharge data tab showing computed runoff volume and peak flow rate for 25 year 24 hour Tainrall event Example BD use Rete A eke ema eae B 9 Figure 1C Lengths of contour lines within the watershed boundary Example C cccccceeeeeeeeeeeeeeeees C 1 Figure 2C Average Slope Calculator button Example C cccccccceccccccceececeeeeeeeaaaeeeeessseseeeeceeeseseeeeaaaas C 2 Figure 3C Average Slope Calculator window Example C cccccccccccccceeceeceeeeeeseeseseseeeeceeeeeeeseeeeeenaaas C 2 EFH2 User s Manual August 2009 List of Tables Table L COUNTY AF record Torma iee n cra 3 Table 2 A portion of the rainfall data file for Nebraska filename COUNTY NE ccccccccsssssssssesesssseeeeeeees 3 Tables Suecested format or SOMS AG Me A A Ni 3 Table 4 Portion of a SOILS HG data file created for the State Of Texas oooooooononnnncnnnnnnnnonononononnonononannnnncnnnnnoss 4 Table Ss Key EUnCiOAS o A E ae aed 5 Table 6 Menu Tes eSCrip OW adi A bina r eskcanstine 7 Table 7 Menu cdt destapa AD A ead eace eee 8 Table Ss Menu View de
8. generalized graphs found in NEH 650 02 to determine a unit peak discharge and then multiplying that figure by the Runoff in inches as determined using the SCS NRCS runoff equation and by the drainage area Runoff fields Runoff volume for the watershed is determined using the SCS NRCS runoff equation defined in NEH 630 10 Estimation of Direct Runoff from Storm Rainfall This runoff volume is multiplied by the unit peak discharge determined using the generalized graphs found in NEH 650 02 to compute a peak flow rate or peak discharge 17 EFH2 User s Manual August 2009 RCN Tab Using the RCN tab Figure 19 the user calculates the runoff curve number for the watershed by entering the appropriate area or percentage of area by land use description and hydrologic soil group Some fields on this screen respond slightly differently to keystrokes than they do in previous screens See the General data entry help screen for function details of keys EFH 2 Estimating Runoff and Peak Discharge File Edit View Tools Help g 83 s C Urban rea C Developing Urban f Cultivated Agriculture Other Agriculture C Arid Rangeland COVER DESCRIPTION CULTIVATED AGRICULTURAL LANDS Fallow Bare soil Crop residue CR poor Crop residue CR good Straight row SA poor Straight row SA good SR Crop residue poor SR Crop residue good Contoured C poor Contoured C good C Crop residue poor C Crop residue good Cont amp
9. next tab stop on the screen Completes data entry for the field and jumps to the previous tab stop on the screen Moves the cursor to the start of the field ee up to the last entry cell in the row End Moves the cursor to the end of the field Moves down to the first entry cell in the row below Page up no action Scrolls up one screen of grid cells Page down no action Scrolls down one screen of grid cells Completes data entry for the field and moves cursor to the previous field Shift Tab RG 4 EFH2 User s Manual August 2009 Example Problem A Problem Statement A grassed waterway is planned in Field 2 of the A B Smith Farm in Frederick County Maryland The drainage area above the site of the proposed waterway indicated by the black dot at the waterway outlet is 90 acres Figure 1A shows the watershed boundary in blue and watershed time of concentration flow path in red Figure 1A Watershed boundary map showing time of concentration flow path Example A The average watershed slope determined by averaging the slopes of the mapped soils is 1 percent and the time of concentration flow path length as measured from the United States Geological Survey USGS topographic map is 3 400 feet EFH2 User s Manual August 2009 Soils data for this watershed was used in conjunction with land use information obtained in the field to determine the appropriate Hydrologic Soil Groups shown in Figure 2A and summarized
10. non silk loam 21 93 Beemont ver gravelly silt loam 3509 D rion silt loan 5991 Pozsumtrot fine sandy loam F5400 Gladden silt loam Source websoilsurvey nncs usda goyv Search by Cloze Figure 20 Hydrologic Soil Groups Window with the file populated Note that this user used a slightly different format than recommended in the SOILS HG optional data file discussion Runoff Curve Numbers A combination of a hydrologic soil group a land use and treatment class cover description is a soil cover complex An index value is assigned to each soil cover complex which indicates its runoff potential during periods when the soil is not frozen and is known as a runoff curve number RCN or CN RCN s are shown on the RCN tab in columns by hydrologic soil group for each cover description Units of area measurement Acres or Percentage Radio buttons The radio buttons in the lower left portion of the screen switch between acres or percentages for data entry The default is Acres If the user wishes to switch to data entry in percentages selecting the Percentage radio button PRIOR TO MAKING ANY DATA INPUTS on the RCN tab will make the change and the Accumulated Area at the bottom of the screen will change from ac to being displayed as 19 EFH2 User s Manual August 2009 If the user has already started inputting data and then decides to change the data input from Area to Percentage the RCN Data Conversion window Figure 21 will app
11. ER BLAINE BOONE BOX BULIE BOYD BROWN NNNNFNN DN NH o o aa ee ee a ss ae eos te N Ww Table 2 A portion of the rainfall data file for Nebraska filename COUNTY NE If used the county rainfall file must reside in the same folder as the EFH2 EXE file If the COUNTY XX file is not available the program will operate properly but the user will be required to enter the rainfall volume frequency data manually SOILS HG The SOILS HG file is used by the Hydrologic Soil Group HSG lookup tool for populating the HSG table The SOILS HG file is a three column text file which can be created using a standard ASCH editor and separating the columns by commas a space or at least one tab If the soils data file is created using an Excel spreadsheet use separate columns for each of the fields and save the file as a comma delimited text file The resulting text file should be checked carefully for extra characters The SOILS HG file does not have a required format so the user is free to enter whatever information he or she wishes in the three columns however if the maximum number of characters is exceeded some of the information may be truncated when the SOILS HG file is viewed in EFH2 A suggested format by column for the SOILS HG file is illustrated in Table 3 Column Maximum STL Data ict of Characters ooo Textural class Hydrologic soil group Table 3 Suggested format for SOILS HG file EFH2 User s Manual Au
12. Figure 11 Toolbar Table 11 gives a brief description of each of the toolbar buttons which correspond to the menu bar items EO I New command S Cut to clipboard command Pl Help command Table 11 Toolbar Button Descriptions Basic data tab Information about the project being evaluated is entered on the Basic data tab Figure 12 EFH 2 Estimating Runoff and Peak Discharge File Edit view Tools Help S jajaj 2 8 amp 8 amp 0 State County Po Practice 0 Bb Date 6 8 2009 Drainage Area Runoff Curve Number Watershed Length feet Watershed Slope percent Time of Concentration hours Figure 12 Basic data tab Client and project location data as well as Practice identification information and user By information are entered directly The remaining data are either directly entered or computed using other tabs and specific notes will appear to indicate that the values were directly entered computed or carried over from elsewhere A more detailed description follows for each of the data entry fields 11 EFH2 User s Manual August 2009 General Project Information Client field Unique project identification information to enable the user to identify the project or client for which the analysis 1s being performed may be entered in this field State field The State field is used to locate the COUNTY XX rainfall data file for the State in which the project being evaluated is l
13. Manual August 2009 D 2 No rainfall data file found for amp State Text amp using default rainfall data file County rf A rainfall data file has not been included for the State indicated If the County rf file has not been developed for the State in interest the user must then enter the rainfall frequency and depth data on the Rainfall Discharge Tab Please enter 2 character State abbreviation code The user may click on the Cancel button and continue entering data with the State and County fields left empty They must then enter the rainfall frequency and depth data on the Rainfall Discharge Tab Rainfall is outside the range of 0 to 26 inches Keep the rainfall depths within this range or use WinTR 55 which accepts rainfalls from O to 50 inches in depth The calculated TC is gt 10 0 hours TC adjusted to 10 00 hrs If the adjusted Tc of 10 00 hours 1s satisfactory continue with the project To use a Tc greater than 10 00 hours the user must employ another program such as WinTR 20 The calculated TC is lt 0 1 hour TC adjusted to 0 10 hrs If the adjusted Tc of 0 1 hour is satisfactory continue with the project To use a Tc less than 0 1 the user must employ another program such as Win TR 20 The Slope is exceeds the limitation 0 1 to 64 Please check your data Correct the slope to fall within the recommended limits or use a different program Time of Concentration can not be less than 0 1 hours Enter
14. USDA ON RCS ee States Department of Agriculture Natural Resources Conservation Service EFH2 Computer Program Estimating Runoff and Peak Discharge User s Manual August 2009 Photo credit NRCSIA99447 The U S Department of Agriculture USDA prohibits discrimination in all its programs and activities on the basis of race color national origin age disability and where applicable sex marital status familial status parental status religion sexual orientation genetic information political beliefs reprisal or because all or a part of an individual s income is derived from any public assistance program Not all prohibited bases apply to all programs Persons with disabilities who require alternative means for communication of program information Braille large print audiotape etc should contact USDA s TARGET Center at 202 720 2600 voice and TDD To file a complaint of discrimination write to USDA Director Office of Civil Rights 1400 Independence Avenue S W Washington D C 20250 9410 or call 800 795 3272 voice or 202 720 6382 TDD USDA is an equal opportunity provider and employer EFH2 User s Manual August 2009 Preface The purpose of this User s Manual is to assist the new or occasional user develop input data and run the EFH2 Computer Program EFH2 is a single event rainfall runoff model used to estimate runoff volume and peak discharge for small single subarea watersheds EFH2 is based on proce
15. Watershed Slope percent Time of Concentration hours Figure 2C Average Slope Calculator button Example C Enter 6 200 feet for the length of the contours 20 feet for the contour interval and 37 acres for the drainage area as calculated from the RCN tab in Example B Average Slope Calculator Sel Ed otep 1 Measure the lengths of all the contours within the watershed boundary and sum their total Length of contours eno feel Contour interval feet Drainage 4rea acres Average Slope percent OR Cancel Figure 3C Average Slope Calculator window Example C The calculated slope is 7 7 percent Proceed with the problem solution following Steps 1 through 4 in Appendix B Note If the user calculates the Average slope by both the methods in Appendix B and C and compares them they will most likely have somewhat different values These differences can result in differences in the final answer The user must then decide which 1s more appropriate to use EFH2 User s Manual August 2009 Errors amp Messages EFH2 has a number of Error Messages and Warnings to assist the user in developing an error free data file These are displayed in windows similar to the example shown below Entry Error A Curve number must be in the range 40 to 98 The Error messages and warnings are listed below with suggestions for correcting the data file Basic Data values are different from RCN values Values on the Basic Dat
16. a tab are different from those in the RCN tab Correct one or the other and continue Could not be found Correct before running EFH2 program The missing data should be added before running the program Curve number must be in the range 40 to 98 Enter curve number within the given range Do you want the save the changes you have made to this data To keep the changes save the data otherwise exit the program losing changes made since the last save Drainage area must be greater than 1 acre Enter drainage area greater than 1 acre Drainage area must be in the range of 1 to 2000 acres Drainage area for the project must be within the limits given Drainage area must be less than 2000 acres Use another procedure Use WinTR 55 or WinTR 20 for the analysis Land use area must equal 100 percent before accepting While using the percentage option on the RCN tab the user has made entries that when added together are less than 100 percent Correct the entries to total 100 percent More than 10 of watershed is urban land use Recommend using TR55 Press Retry to revise or Cancel to Exit EFH2 is not recommended for use in watersheds with greater than 10 percent urban land use Revise the data or use another program such as WinTR 55 or WinTR 20 Must enter data before accepting The user must enter some data on the RCN tab before clicking on the accept button Enter some data and continue D 1 EFH2 User s
17. ak discharge and runoff volume utilizing the generalized tables and graphs found in NEH 650 02 EFH 2 Estimating Runoff and Peak Discharge File Edit View Tools Help Dls al el Bale gt 2 i Rainfall Type Frequency yrs 24 HR Rain Peak Flow fin cfs Storm 1 Storm 2 Storm 3 Storm 4 Storm 5 Storm 6 MINITI Storm 7 Figure 17 Rainfall Discharge data tab Rainfall Type field The user must enter the Rainfall Type appropriate for the State in which the project is located directly For the United States appropriate NRCS rainfall data distribution is determined based upon the map shown in Figure 18 In some cases based upon State specific evaluations States use a distribution that is different than that displayed in Figure 18 po N l 4 AS E SS gt A SY Reinfell PES Distribution fe gt H Type I SS ll S S Type IA AA Type 11 Type 111 v Figure 18 Approximate geographic boundaries for NRCS rainfall distributions 16 EFH2 User s Manual August 2009 For watersheds located in the Delaware Maryland Virginia or Delmarva peninsula a rainfall distribution type identified as DMV is identified The DMV is a combination of the NRCS Type II rainfall distribution and a dimensionless unit hydrograph developed specifically for the Delmarva peninsula which yields better predictions of peak discharges for that part of the country than does use of the NRCS Type II di
18. arried over to the Runoff Curve Number field on the Basic data tab and the from RCN Calculator note appears Time of concentration data and computations If time of concentration T is known the user may skip the Watershed length and Watershed slope fields and enter the T directly in the Time of Concentration field and the note user entered will display If T is not known the user must enter Watershed length and Watershed slope to compute T In this case the note calculated will appear Watershed length field Watershed length or flow length is defined as the path along which water flows from the watershed divide to the outlet For hydrologic evaluation purposes this path is identified to be from the hydraulically most distant point along the watershed divide to the watershed outlet In other words it is the path runoff will take which takes the longest time to reach the outlet If the user is computing T within EFH2 the Watershed length must be entered directly Flow length can be measured using aerial photographs quadrangle sheets or Geographic Information System GIS techniques Kent 1973 developed a relationship between flow length and drainage area characteristics useful for estimating watershed flow length l 209A where flow length feet A drainage area acres 13 EFH2 User s Manual August 2009 Watershed Slope field The watershed slope or average watershed land slope is used in the lag equation to est
19. ation The program window displays best at a screen resolution of 1076 x 768 pixels or higher Lower resolutions or reduced screen sizes may cut off some text Program Limits EFH2 is applicable to single subarea watersheds where e The watershed can accurately be represented by a single runoff curve number between 40 and 98 e The watershed drainage area is between 1 and 2 000 acres e The watershed hydraulic length is between 200 and 26 000 feet e The average watershed slope is between 0 5 and 64 percent Slopes from 0 1 to 0 49 percent may be used with caution but a warning message will be generated An error message will be generated by entering slopes greater than 64 percent e No valley or reservoir routing is required e Urban land use within the watershed does not exceed 10 percent e The rainfall is between 0 0 and 26 inches Data Requirements The following basic information about the watershed must be derived or obtained in order to use EFH2 for hydrologic analyses 1 Watershed Drainage Area The watershed must be delineated to determine its size 2 Land use Information Land use information is required for determining the watershed runoff curve number CN Land uses are described in the CN tables in EFH2 3 Soils Information Soils information hydrologic soil groups HSG A B C or D is required for determining the watershed CN 4 Topographic information Topographic information for the watershed is required for es
20. creen with the message that it comes from the RCN calculator If the user then uses the Slope calculator and changes the area the changed area appears on the basic data screen but the message attributing the area to the RCN screen remains There are a number of notes that might display depending upon how the Drainage Area data was entered e Ifthe user enters the Drainage Area on the Average Slope Calculator window the value is carried from that window to the Basic data tab and no note appears to indicate the source of the data e Ifthe user enters Drainage Area directly on the Basic data tab the note user entered is displayed e If the user utilizes the RCN tab with the Acres option selected upon completion of data entry and clicking the Accept button the Accumulated Drainage Area rounded to the nearest acre is carried over to the Drainage Area field on the Basic data tab and the note from RCN Calculator 1s displayed e If the user utilizes the RCN tab with the Percentage option selected no Drainage Area entry is carried over to the Drainage Area field and the user must enter it manually on the Basic Data tab or in the Average Slope Calculator window Curve Number field If the user enters a runoff curve number directly in this field the user entered note appears Another option is to compute the curve number using the RCN tab Upon completion of data entry on the RCN tab and clicking the Accept button the Weighted Curve Number value is c
21. dures defined in the Natural Resources Conservation Service NRCS National Engineering Handbook Part 650 NEH 650 Engineering Field Handbook EFH Chapter 2 Estimating Runoff and Peak Discharge NEH 650 02 and the National Engineering Handbook Part 630 Hydrology NEH 630 EFH2 is a Windows version of the EFM2 DOS computer program originally developed by the Soil Conservation Service SCS now NRCS in October 1990 Problems with the EFH2 Computer Program should be reported to the NRCS State Conservation Engineer within your State Acknowledgements The original DOS version of the EFM2 computer program was developed by William Merkel Hydraulic Engineer NRCS Washington D C Corey Wright IT Specialist NRCS CO and Ralph Roberts Computer programmer Agricultural Research Service ARS MD The first EFH2 Windows computer program was developed by Owen Kvittem NRCS retired The User s Manual was developed by Quan D Quan Hydraulic Engineer NRCS West National Technology Support Center WNTSC Claudia C Hoeft National Hydraulic Engineer NRCS Washington D C Geoffery Cerrelli Hydraulic Engineer NRCS PA Helen Fox Moody Hydraulic Engineer NRCS WNTSC and William Merkel Hydraulic Engineer NRCS WNTSC The Texas SOILS HG data file and the Nebraska COUNTY NE rainfall data file were provided and verified by Terry Costner Hydraulic Engineer NRCS TX and Arlis Plummer Hydraulic Engineer NRCS NE The cover ph
22. e development of these curves is beyond the scope of this User s Manual because of the complexity of the procedure Distributions may be removed from the file to limit selection to only those distributions for which local users have a need The TYPE RF file must reside in the same folder as the EFH2 EXE file EFH2 will not operate if the TYPE RF file is unavailable Optional files The optional data files are the COUNTY XX and SOILS HG files Optional data files can be created and edited by the user and are accessed by the program automatically if the filenames are maintained COUNTY XX The COUNTY XX file is an optional data file containing rainfall volume frequency data for up to seven return intervals by county name The presence of a county rainfall data file simplifies use of EFH2 by making rainfall volume data accessible by dropdown list COUNTY XX refers to a county file created for a specific location where XX indicates location To accommodate State specific files it is suggested that the file name use the format COUNTY XX where XX is the two letter State postal abbreviation example COUNTY NE When a two letter State abbreviation is entered as part of the EFH2 data input a search is made for the appropriate COUNTY XX file When a match is found the appropriate COUNTY XX file is used and county names are displayed using that State file If a match is not found for COUNTY XX then the default rainfall file COUNTY RF if available is
23. e Calculator Length of The sum of the lengths of all the Step 1 Measure the lengths of all the contours Contours contours within the watershed within the watershed boundary and sum their total The difference in elevation Contour between adjacent contours This Peal interval must be the same interval for all contour lengths measured Contour interval feet Drainage The area in acres within the Aoa watershed boundary contributing to Drainage rea acres the project site e NA Pa The calculated average slope in LE ERES percent of all the contributing land Average within the watershed boundary lt is DK Caan the product of the length of contours times the contour interval divided by the drainage area Length of contours Optional hydrologic soils groups data file Search for Hydrologic Soil Group Map Unit Humber and Mame 6601 4 H aymond silt loan 73135 Union silt loam 73193 Beemont vern gravelly silt loam 3509 L rion silt loam 2539 Possumtrot fine sandy loam 5400 Gladden silt loam Source websolsurvey nes usda gov Search by Close SOILS HG Hydrologic Soil Group Window Format of the SOILS HG file is at the discretion of the user Three columns may be used with whatever information the user chooses to include however the columns have restrictions on the numbers of characters A suggested format for the SOILS HG file by columns is shown Column NINOS Data Description of Charac
24. e list 1s developed distributed and maintained Individual users might consider maintaining a small list for their own use Further information on HSG classification can be found in NEH 630 07 Hydrologic Soil Groups and the NRCS National Soil Survey Handbook NSSH User Responsibility Results from any computer model can be sensitive to the quality of the input data It is the user s responsibility to ensure that all input data whether entered or implied through default values is appropriate for the situation being analyzed EFH2 User s Manual August 2009 User Interface Data Entry The user starts data entry on the Basic data tab with the Client field and progresses through each of the entry fields The user moves between entry fields using either the Enter or Tab keys to move forward or traverses backwards using Shift Tab Pressing the ESC key returns a field to its initial value if a mistake is made during entry Calculated fields are automatically updated when sufficient valid data have been entered for making the calculation Warning messages appear 1f invalid entries are made After the Basic data tab fields are populated the user typically proceeds to the Rainfall Discharge data tab to continue data entry and view results Help is available regarding data entry rules for State County Drainage Area Runoff Curve Number and Time of Concentration fields through the Help button or the Menu Help Table 5 provides details re
25. eak Flow ir cts Storm E E Storm 2 Storm 3 Storm 4 Storm 5 Storm 6 Storm 7 Figure 10B Rainfall Discharge data tab showing computed runoff volume and peak flow rate for 25 year 24 hour rainfall event Example B Conclusion The 25 year 24 hour rainfall of 6 1 inches results in a peak flow rate of 66 cfs and a runoff volume of 2 7 inches The design capacity peak flow rate to use in sizing the diversion is 66 cfs EFH2 User s Manual August 2009 Intentionally Blank EFH2 User s Manual August 2009 Example Problem C Problem Statement The site 1s the same as in Example B except that the EHF2 Average Slope Calculator will be used to calculate the Average Watershed Slope From the watershed map measure the length of the contour lines and sum them A Figure 1C Lengths of contour lines within the watershed boundary Example C The total length of all the contour lines in the watershed 500 1 000 1 200 1 200 1 200 1 100 6 200 The contour line interval is 20 feet The drainage area is 37 acres EFH2 User s Manual August 2009 Click on the Average Slope Calculator Button EFH 2 Estimating Runoff and Peak Discharge File Edit View Tools Help Chent Kennedy Stake PA County ILAN CASTER Practice Diversion By Date 3 19 2009 Drainage Area acres from RCH Calculator Runoff Curve Number 72 from RCH Calculator Watershed Length 3300 feet
26. ear asking 1f the data already input should be converted at all be converted based upon the area already entered or based upon the drainage area as input on the Basic Data tab w RCM Data Conversion Convert Acres to Percent How would you like to convert the values in the worksheet from acres to percent f Mo conversion use current values directly f Determine percentage from worksheet total area of 40 00 f Determine percentage from Basic Data drainage area of 100 Figure 21 If the user originally indicated percentages as the units for data input and then decides to switch to acres the Acres radio button may be selected and the RCN Data Conversion window Figure 21 will appear however the option to determine percentages from the worksheet total area will not be available as an option Repeatedly going back and forth between acres and percentages is not recommended Weighted Curve Number The Weighted Curve Number for the watershed is computed automatically as the user enters land use hydrologic soil group data and displayed at the bottom center of the RCN tab Accumulated Area The total Accumulated Area of the watershed is calculated as the user enters land use hydrologic soil group data and displayed at the bottom center of the window below the Weighted Curve Number This total includes all land use descriptions used to describe the watershed drainage area As additional areas are entered or deleted the summary values chan
27. ed with Crop Residue in good condition includes 2 acres in field C and 12 1 acres in field C EFH 2 Estimating Runoff and Peak Discharge File Edit View Tools Help f Ba os C Urban Area C Developing Urban e Cultivated Agriculture Other Agriculture Ard Rangeland COVER DESCRIPTION A Crop residue CR 76 Crop residue CR Row crops Straight row SA Straight row SA SR Crop residue SR Crop residue Contoured C Contoured C C Crop residue C Crop residue Cont amp terraced C amp T Cont amp terraced C amp T C amp T Crop residue C amp T Crop residue Small grain Straight row SA Straight row SR SA Crop residue SA Crop residue Contoured C Contoured C C Crop residue C Crop residue Cont amp terraced C T Cont amp terraced C T C amp T Crop residue C amp T Crop residue Close seeded Straight row legumes or Straight row tntatin Pontarerd 4 f Acres Weighted Curve Number 68 Percentage Accumulated Area ac 37 20 Figure 6B RCN tab Example B As summarized at the bottom of the RCN tab and shown in Figure 6B the Weighted Curve Number computed by EFH2 is 68 and the Accumulated Area is 37 20 acres When data entry is complete click Accept to automatically return to the Basic data tab EFH2 User s Manual August 2009 Step 3 Basic data tab Upon returning from the RCN tab note the purple text indicating Drainage Area and Runoff Curve Number we
28. ent The program will run with slopes between 0 1 and 0 5 but the user should check the results carefully Weighted Curve Number not in range 40 to 98 Revise the data so that the Weighted Curve Number is within the recommended limits D 3
29. erraced Crop Residue Good Cond Table 1B Drainage area soil cover complexes Example B Figure 3B shows the watershed boundary red line and the flow path identified as the T flow measuring 3 300 ft Figure 3B Topo map showing watershed boundary and T flow path Example B Figure 4B shows the watershed boundary red line and 3 lines identified for estimating the watershed average slope Figure 4B Topo map showing watershed drainage area shaded blue and three lines for determining average watershed slope Example B EFH2 User s Manual August 2009 The average watershed slope was calculated by determining the slopes of the individual lines computed by determining the elevation drop along the line and dividing by the length of the line and averaging the slopes of the three individual lines as shown in the following computation Slope of line 1 2 0 044 ft ft 900ft Slope of line 2 a 0 10 ft ft A400 ft AO tt Slope of line 3 0 088 ft ft A50ft Average Slope SS 0 077 ft ft 7 7 The COUNTY PA rainfall data file for Pennsylvania is not available However standard rainfall references were consulted to determine that the 25 year 24 hour rainfall event yields 6 1 inches of rain Pennsylvania uses a Type II NRCS Standard Rainfall Distribution EFH2 User s Manual August 2009 Solution Step I Basic data tab Enter the Client Practice and By information Since the COUNTY PA rai
30. fall should use the format shown here by row and column RG 3 EFH2 User s Manual August 2009 EFH 2 Estimating Runoff and Peak Discharge File Edit View Tools Help amp Gs gt rs 9 Raintall Discharge data C Urban Area Developing Urban Cultivated Agriculture Other Agriculture C Arid Rangeland COVER DESCRIPTION A C CULTIVATED AGRICULTURAL LANDS Fallow Bare soil Crop residue CR poor Crop residue CR good Row crops Straight row SA poor Straight row SA good SA Crop residue poor SA Crop residue good Contoured C poor Contoured C good C Crop residue poor C Crop residue good Cont amp terraced C amp T poor Cont amp terraced C T good C amp T Crop residue poor C amp T Crop residue good Small grain Straight row SA poor Straight row SA good SR Crop residue poor SA Crop residue good Contoured C poor Canteiired IM nan Acres Weighted Curve Number C Percentage Accumulated Area ac RCN Tab Function Basic pamend Rainfall Discharge RCN Tab Display Help Display Help Toggles between entry fields and menu bar eels Y UL cules ne Returns field value to previous value Returns field value to previous value Deletes the character to the right of the cursor Clears the entire field Backspace Deletes the character to the left of the cursor rani e NGIL esla ere advances to the next field advances to the next field advances to the next field jumps to the
31. garding the functions of various keys on the Basic data tab fields Rainfall Discharge data tab fields and the RCN tab fields Note that function keys may operate slightly differently in the grid cells on the RCN tab than on the other tabs Function Basic Data and Rainfall Discharge RCN Tab Tab Display Help Display Help Toggles between entry fields and menu bar Toggles between entry fields and menu bar Returns field value to previous value Returns field value to previous value Deletes the character to the right of the cursor Clears the entire field Deletes the character to the left of the cursor Delete the last right most character in the field Completes data entry for the field and Completes data entry for the field and advances to the next field advances to the next field Completes data entry for the field and Completes data entry for the field and advances to the next field jumps to the next tab stop on the screen Shift Tab Completes data entry for the field and moves Completes data entry for the field and cursor to the previous field jumps to the previous tab stop on the screen Moves up to the entry cell above above row below Page up no action Scrolls up one screen of grid cells Page down no action Scrolls down one screen of grid cells Table 5 Key Functions Tool TipHelp Pausing the mouse pointer briefly over a field will display an abbreviated pop up help for each data entry field EFH2 User s Manua
32. ge If both boxes are blank no detailed land use description data has been entered for this subarea Accept button Click the Accept button to retain all data entered on the window and transfer appropriate values for drainage area and runoff curve number to the Basic data tab Clear button Clicking on the Clear button will clear all data entries of area by land use previously entered 20 EFH2 User s Manual August 2009 References United States Department of Agriculture Natural Resources Conservation Service 2009 National Engineering Handbook Part 630 Hydrology Chapter 7 Hydrologic Soil Groups Washington D C NEH 630 07 United States Department of Agriculture Natural Resources Conservation Service 2004 National Engineering Handbook Part 630 Hydrology Chapter 9 Hydrologic Soil Cover Complexes Washington D C NEH 630 09 United States Department of Agriculture Natural Resources Conservation Service 2004 National Engineering Handbook Part 630 Hydrology Chapter 10 Estimation of Direct Runoff from Storm Rainfall Washington D C NEH 630 10 United States Department of Agriculture Natural Resources Conservation Service Draft 2009 National Engineering Handbook Part 630 Hydrology Chapter 15 Time of Concentration Washington D C NEH 630 15 United States Department of Agriculture Natural Resources Conservation Service 2007 National Engineering Handbook Part 630 Hydrology Chapter 16 Hydrographs Wa
33. gust 2009 A portion of the SOILS HG file developed for Texas is shown in Table 4 This data file was developed using Excel Abilene Abilene Acadia Acme Acme ACove CONS ACULE Acuff Acuff Acuna Adaton Addicks Table 4 Portion of a SOILS HG data file created for the State of Texas Note that the Abilene Acme Acove and Accuff soils in this examples have multiple listings with different textures ote Peres O a e Fes er e Q A SOILS HG file is not included with the EFH2 installation package If a SOILS HG file is created it must be saved with the filename SOILS HG and stored in the EFH2 program folder to be useable by EFH2 Unlike the COUNTY XX file there is no option for designating separate SOILS HG files by State The file extension HG must be maintained or EFH2 will not be able to locate the file NRCS does not maintain a national list of soils by hydrologic soil group in any engineering directives Any old national lists are obsolete due to revisions and updates to soil surveys and they should be discarded or used with caution The most up to date information on assigned hydrologic soil groups is available through the NRCS Field Office Technical Guide published soil survey data bases the NRCS Soil Data Mart Web site http soildatamart nrcs usda gov and or the Web Soil Survey Web site hittp websoilsurvey nrcs usda gov It is at the discretion of the NRCS State Conservation Engineer whether or not a Stat
34. ic data tab Step 3 Basic data tab Upon returning from the RCN tab note the purple text indicating Drainage Area and Runoff Curve Number were developed using the RCN Calculator Figure 5A EFH 2 Estimating Runoff and Peak Discharge File Edit view Tools Help S e gt l 2 Basic data Rainfall Discharge data Client A B Smith Farm State MD County FREDERICK Practice waterway Field 2 By Fm Date 3 9 2009 acres from RCN Calculator from RCN Calculator feet Watershed Slope percent Time of Concentration hours Figure 5A Basic Data tab showing drainage area and runoff curve number carried over from RCN tab Example A EFH2 User s Manual August 2009 Enter the Watershed Length the length of the flow path and the Watershed Slope The program automatically calculates Time of Concentration utilizing the lag equation and displays the information with a note in purple text indicating that the time of concentration was calculated Alternatively if time of concentration is already known the user may enter it directly upon which a note indicating that the value was user entered is displayed EFH 2 Estimating Runoff and Peak Discharge EE x Fie Edit wiew Tools Help Delal al lele ll PY Basic data Raimfall Discharge data Client A B Smith Farm State MD County FREDERICK Practice Waterway Field 2 Bw hem Date 3 9 2009 ACTES from RCN Calculator from REN Calculator feet Watershed Slope
35. imate the watershed T See NEH 650 02 and NEH 630 15 Time of Concentration for more information on the lag method Watershed slope is not to be confused with the slope of the flow path The average land slope for small watersheds can be determined several different ways e using GIS techniques e by assuming land slope is equal to the soil map unit slope as published in the soil survey e by using a clinometer to measure landform slope in the field e by drawing three to four lines perpendicular to the contour lines in various locations on the watershed map to best represent average slope based on spacing of the contour lines see Appendix B e by determining the average of the land slope from grid points using a dot counter and e by using the following equation from Chow 1964 and illustrated in Appendix C y 100 CI A where Y average land slope percent C summation of the lengths of all contour lines corresponding to the contour interval that pass through the watershed drainage area on the quad sheet feet I contour interval feet A drainage area f 1 acre 43 560 ft If using EFH2 to compute T a Watershed Slope must be entered However Watershed Slope may be carried over from the Average Slope Calculator dialogue window Figure 15 This window is available only when the Basic Data tab is activated Data inputs are the sum of the lengths of all the contours within the drainage area boundary the associa
36. in Table 1A Figure 2A HSG boundaries within the project watershed Example A pela ol Cover Description B__ Pasture Good Condition Pasture Good Condition Condition Woods Poor Condition Table 1A Drainage area soil cover complexes Example A Straight Row Crops Good m Maryland uses a Type II rainfall distribution for hydrologic analyses Grassed waterway design is based on a 10 year peak discharge Determine the peak discharge for the 10 year storm event EFH2 User s Manual August 2009 Solution Step 1 Basic data tab Enter the Client State County Practice and By information Date will automatically fill in to the current date If the COUNTY MD file does not exist in the EFH2 program folder a warning message will appear indicating that no rainfall data file was found for MD and that the program is defaulting to the COUNTY RF file Click OK if that message appears Frederick County rainfall data 1s included in the COUNTY RF file and Frederick will appear in the County dropdown list Do not enter the Drainage Area Instead 1t will be calculated along with Runoff Curve Number on the RCN tab The Basic data tab should appear as shown in Figure 3A upon completion of this portion of the data entry EFH 2 Estimating Runoff and Peak Discharge File Edit View Tools Help Delal S ela e 9 Basic data Raintall Discharge data Client A B Smith Farm State MD County Frederick
37. l August 2009 Welcome to EFH 2 Computer Program Window Welcome to EFH 2 for Windows EFH 2 Engineering Field Handbook Chapter 2 Hydrology Natural Resources O N R C Conservation Service Disclaimer Although EFH 2 has been tested by its developers NO warranty expressed or implied is made as to the accuracy and functioning of the program and related program material nor shall the fact of distribution constitute any such warranty and NO responsibility is assumed by the developers in connection therewith Figure 1 Welcome to EFH2 for Windows Upon starting the EFH2 Computer Program the Welcome to EFH2 for Windows window Figure 1 displays with the disclaimer Although EFH 2 has been tested by its developers NO warranty expressed or implied is made as to the accuracy and functioning of the program and related program material nor shall the fact of distribution constitute any such warranty and NO responsibility is assumed by the developers in connection therewith Program Window EFH 2 Estimating Runoff and Peak Discharge SEF File Edit View Tools Help Olea S ejej gt 9 Raintal Discharge data Peak discharge is determined by procedures contained in NRCS Engineering Field Handbook Chapter 2 Information needed to use this procedure include watershed characteristics drainage area curve number watershed length watershed slope and rainfall amount and distribution The method applies when Wa
38. ly and the note user entered displays If the user is calculating T within EFH2 as soon as sufficient valid data exist in the Runoff Curve Number Watershed Length and Watershed Slope fields T is computed using the lag equation and displayed with the note calculated Subsequent changes to the Runoff Curve Number Watershed Length or Watershed Slope fields will automatically replace the user entered data with the new calculated value The lag equation is used to compute T within EFH2 a 198 5 1 1140Y where T time of concentration hours l flow length feet Y average watershed land slope percent S maximum potential retention inches _ 1 000 10 CN CN runoff curve number More information on the derivation of the lag equation can be found in NEH 630 15 15 EFH2 User s Manual August 2009 Rainfall Discharge data tab If a COUNTY XX file exists EFH2 automatically populates the storm data Frequency and Storm fields on the Rainfall Discharge data tab Figure 17 as soon as a State and county are identified on the Basic data tab but the user must select the Rainfall Type If no COUNTY XX file exists the user must enter the Rainfall Type and storm data directly Peak flow and Runoff volume are computed values displayed only when sufficient data has been entered into the Basic data tab into the Rainfall Type and storm data Frequency and Storm on this tab and or on the RCN tab to complete computation of the pe
39. n Choice Explanation Help Contents Opens the program help file Figure 9 About Opens a dialog window containing general information about the EFH2 program Figure 10 Table 10 Menu Help Description EFH2 User s Manual August 2009 E EFH2 Help S Er gt Print Options gt ST ENGINEERING FIELD B System requirements H A N D BOO K B Basic Data Files User Interface Data Entry EFH2 E Glossary Estimating Runoff and Peak Discharge The EFH2 software implements the procedures described in the NEH 650 Engineering Field Handbook Chapter 2 EFH2 for estimating runoff and peak discharge More details about the concepts of this software may be found in this handbook Figure 9 Help Contents Dialog Window About EFH 2 Engineering Field Handbook Chapter 2 E EFH2 Estimating Runoff and Peak Discharge Version 1 7 0 Date March 2003 This program models the hydrology procedures defined in the Engineering Field Handbook Chapter 2 EFH2 is a single event raintall runott small watershed model Written by Owen Evittem Lincoln NE Redeveloped from DOS version 1 20 Oct 1990 originally written by Ralph Roberts SAS Bill Merkel and Corey Wright SES Figure 10 Help About Dialog Window 10 EFH2 User s Manual August 2009 EFHB2 Toolbar The EFH2 Toolbar Figure 11 is displayed directly below the menu bar It offers quick access to the most often used program commands S 4am gt e P
40. nd slope Example B EFH2 User s Manual August 2009 Step 4 Rainfall Discharge data tab Click on the Rainfall Discharge data tab Since no rainfall data was available for Pennsylvania this tab will initially display with blanks as shown in Figure 9B and data will have to be manually entered F EFH 2 Estimating Runoff and Peak Discharge Fie Edit View Tools Help Di co fl S slale gt 2 Rainfall Type Frequency yrs 4 HR Rain Peak Flow in cts Storm 1 Storm 2 Storm 3 Storm 4 Storm 5 Storm 6 Storm 7 Figure 9B Blank Rainfall Discharge data tab Example B Select the Rainfall Type II for Pennsylvania For Storm 1 enter 25 for Frequency and 6 1 inches for the 24 hour rain The rainfall data Rainfall Type and rainfall volumes 24 hour rainfall amounts by Frequency and Storm for up to 7 storms can be displayed on the Rainfall Discharge data tab for the county State combination entered on the Basic data tab EFH2 User s Manual August 2009 Provided that data on the Basic data tab is complete the discharge data Peak flow and Runoff volume for the 25 year storm is calculated and displayed as shown in Figure 10B If the values are not displayed return to the Basic data tab and ensure that data entry is complete F EFH 2 Estimating Runoff and Peak Discharge Sele File Edit View Tools Help Delal el lee gt Raintall Type 1 ba Frequency yr 24 HA Rain P
41. nfall data file is unavailable leave the State field blank and select Cancel when prompted with the Entry Error to enter the State abbreviation Type Lancaster into the County field The Date field will automatically fill in to the current date Do not enter the Drainage Area Instead it will be calculated along with Runoff Curve Number on the RCN tab The Basic data tab should appear as shown in Figure 5B upon completion of this portion of the data entry EFH 2 Estimating Runoff and Peak Discharge AmA File Edit View Tools Help Deal e seel fel 9 Basic data Ramntall Discharge data Client Kennedy State County Lancaster Practice A By ffm Date 3 9 2009 Drainage rea Aunoff Curve Number Watershed Length feet Watershed Slope percent Time of Concentration hours Figure 5B Basic Data tab Example B EFH2 User s Manual August 2009 Step 2 RCN tab Click on the RCN tab and enter the appropriate soil cover complex and area information in order to calculate the runoff curve number for the watershed Note that farm fields A and C and also C and D have the same land use soil cover complexes for part of their total acreage The acres for these similar cover descriptions will need to have their acreage combined and reported as one value in the table Upon completion of data entry the RCN tab should appear as shown in Figure 6B Notice that the entry of 14 1 acres for Row Crop Contoured and Terrac
42. nnnnnnnnnnnnnno 16 Broure 19 RGN Tabs A E 18 Figure 20 Hydrologic Soil Groups Window with the file populated ooooonnnncncccnnnnnccnnnnnononnnonanncnnnnnnnnnnos 19 Figure 21 RCN Data Conversion Wit OW ns 20 Figure 1A Watershed boundary map showing time of concentration flow path Example A A 1 Figure 2A HSG boundaries within the project watershed Example A ooocccncncnncncnononnnonononononnnnnnncnnnnnnnnos A 2 Ficure 3A Basic Data tab Example A ciclista A 3 Pieure 4A REN ab Example A A peee Melee Stee ne sep aataeecaes A 4 Figure 5A Basic Data tab showing drainage area and runoff curve number carried over from RCN tab O Na as heise ats ara saat O A 4 Figure 6A Basic Data tab showing time of concentration data calculated from user input watershed length and slope CX ANIC a ii ia n A 5 Figure 7A Ramtall Dischatee data tab Example A uni A iia dia A 6 Figure IB Location map Example Basie ici iria B 1 Figure 2B Aerial photo of project area Example Bl a A B 1 Figure 3B Topo map showing watershed boundary and T flow path Example B ooocccccnncnncccncconinono B 2 Figure 4B Topo map showing watershed drainage area and three lines for determining average watershed Opel o ds B 2 Figure 5B Basic Data tab Example B oooooooonocoooooanaccccnccnnnnnnnnnnnononononnnnnnnnnnnnnnnnnnnnnnnnnnnononnnnnnnnnnnaannnanoss B 4 Figure 6B REN Tab Example Dri id B 5 Figure 7B Basic Data tab showing
43. ocated If no entry is made the County field will remain blank as will the rainfall data fields on the Rainfall Discharge data tab and the user will be required to enter the rainfall data manually This field accepts only two character State postal abbreviations If the user attempts to leave this field without entering a code an entry error message will appear Figure 13 Entry Error A Please enter 2 character skate abreviation code i Cancel Figure 13 State field Entry Error Message Selecting OK returns the user to the State field for correction Selecting cancel clears the field and moves the cursor to the next data entry field If the user enters a State abbreviation for which no rainfall data file 1s available see the following discussion on County field a warning error message Figure 14 appears advising the user that no rainfall data file was found C Program Files USDA EFH 2 County DE Figure 14 Rainfall data file not found warning message County field If a rainfall file is available entering the two character State postal code in the State field will bring up the list of counties from the COUNTY XX file this list is available as a dropdown list for this field Selecting the county name from the dropdown list reads the associated precipitation data into the appropriate fields on the Rainfall Discharge data tab Typing the first few letters of the county name will scroll the dropdown list to any matching value
44. on 1s planned above a barnyard agricultural waste handling facility on the Kennedy farm in Lancaster County Pennsylvania as shown on the Location map in Figure 1B The diversion conservation practice standard 362 requires a minimum capacity of the 25 year peak discharge to protect against flows toward an animal waste management system The watershed boundary dashed red line planned diversion location heavy blue line field boundaries solid yellow lines contours dark gray lines and soil boundaries light gray lines are shown on the aerial photo Figure 2B The soil cover complexes are summarized in Table 1B for each of the fields in the watershed drainage area aly m a a 7 ml a Y iil a _ er git F pa z oe ay n j T Ea Y 7 a Poe AL MA y z L T a Pon e k T a R e 7 E Y j aa a J E g po E e P i a 1 f r i 5 t i A e Figure 2B Aerial photo of project area Example B EFH2 User s Manual August 2009 Cover Description Close Seeded Legume Straight Row Good Cond Close Seeded Legume Straight Row Good Cond Woods Good Condition Woods Good Condition Close Seeded Legume Straight Row Good Cond Small Grain Contoured Terraced Crop Residue Good Cond Small Grain Contoured Terraced Crop Residue Good Cond Row Crop Contoured amp Terraced Crop Residue Good Cond Row Crop Contoured amp Terraced Crop Residue Good Cond Row Crop Contoured amp T
45. otograph of a grassed waterway in Fayette County Iowa was taken by Tim McCabe NRCS IA in 1999 NRCSIA99447 EFH2 User s Manual August 2009 Intentionally Blank EFH2 User s Manual August 2009 Table of Contents Contents KEE E E E E A ee Te eee en eee en Te sere re ee eR See 1 ACKENOWICA CEMSA ib 1 Table OE Contents iii A SS AA AA A a 111 rodicio oad di el tus salen ii l WV Fiat is EF UD ee een eee eee eee ee ones 1 System Req Meis A E A EAN 1 Programi Lims oe a A a se Data Requirements ai A cas be ee dacs AA A did l Basic Data Files a 2 Required Jiles oee aa tae aun os O 2 Ophonal TUE a o e b nde 2 User Responsible a ge eg ne ee ne Oe 4 Usor mner E e a topado 5 DAA ENIE enn T E E O 5 Welcome to EFH 2 Computer Program WIiNdOW occccccccoooncccnnncnnnnnoncccnnnnnnnnnnnncncnnnnnnnnnnononcnnnnnnnnnnaninonss 6 Program WIMd0W aid 6 IA EE 2 MENUDO A aL E O A 7 a OBS RAY LLL EE Be eee Ree RT CEES ES Ne LENE STEERS MORENO EER EN Ae ee aye MOTE eTR Te NR aE er ae erm PE eee 1 LEA tt ace II O O tl has 1 General Project Tn OT MANO ii adi 12 Watersned Da ES A A E san caucstaaeae hs eetietaneeie ie 13 Time of concentration data and computations oooonnnnnnnnnnnnnnnnnnnononnnnnnnonononononannnnnnnncnnnnnnnnn nn nn nn nn nnnnnnnnos 13 Rainfall Discharge data tab oocccccccnccnnnonononoonnnonnnnnnnnnnnnnnnnononononnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnss 16 SOTM DOA E SS E AA 17 DISCRATZE CAE
46. percent Time of Concentration 150 hours calculated Figure 6A Basic Data tab showing time of concentration data calculated from user input watershed length and slope Example A EFH2 User s Manual August 2009 Step 4 Rainfall Discharge data tab Click on the Rainfall Discharge data tab The rainfall data rainfall volumes 24 hour rainfall amounts by Frequency and Storm for 7 storms are displayed for the county State combination entered on the Basic data tab Select the Rainfall Type II storm for Maryland Provided that data on the Basic data tab is complete the discharge data Peak flow and Runoff volume for each of the 7 storms are calculated and displayed Figure 7A If the values are not displayed return to the Basic data tab and ensure that data entry 1s complete EFH 2 Estimating Runoff and Peak Discharge E E E Fie Edit View Tools Help Delal Sl ejej foo 2 Rainfall Type 11 Frequency yrs 4 HR Rain Peak Flow iri cts Storm 1 Storm 2 Storm 3 Storm 4 Storm 5 Storm Hb Storm 7 Figure 7A Rainfall Discharge data tab Example A Conclusion The 10 year 24 hour rainfall event of 5 00 inches results in a peak discharge of 104 cfs and a runoff volume of 2 71 inches as shown in Figure 7A for Storm 4 The design flow rate of 104 cfs should be used in sizing the grassed waterway EFH2 User s Manual August 2009 Example Problem B Problem Statement A diversi
47. re developed using the RCN Calculator Figure 7B EFH 2 Estimating Runoff and Peak Discharge Sng File Edit View Tools Help Deal S selel gt Raintall Dischange data Client Kennedy Coun Lancaster Practice Diversion aaa E ch Date 3 9 2009 acres from ACN Calculator from RCN Calculator feet Watershed Slope percent Time of Concentration hours Figure 7B Basic Data tab showing drainage area and runoff curve number carried over from RCN tab Example B Enter the Watershed Length measured previously as described in the problem introduction to be 3 300 feet and the average Watershed Slope computed as described in the problem introduction of 7 7 percent EFH2 User s Manual August 2009 The program automatically calculates Time of Concentration using the Lag equation to be0 698 hours and displays it as 0 70 hours with a note in purple text to indicate that the Time of Concentration was calculated as illustrated in Figure 8B EFH 2 Estimating Runoff and Peak Discharge ama File Edt wiew Tools Help al el selel gt i 9 Client Kennedy State County Lancaster Practice Diesin By ech Date 3 9 2009 Drainage rea acres from ACH Calculator Runoff Curve Number gg fom RCN Calculator Watershed Length 2200 feet Watershed Slope 7 percent Time of Concentration q hows calculated Figure 8B Basic Data tab showing time of concentration data calculated from user input watershed length a
48. scripta daa init 8 Tables Menu Pools Descrip nous sGe E tian sbasaduodst aan te eeanoacte E 9 Table10 Meni help deSCri Pi OM igcdacis conti Gohatakatenuteckee ects a tau E a r E 9 Table 11 Toolbar Button Descnipuons aces ttas nascent E incs bale ana Saat are wa 11 Table 1A Drainage area soil cover complexes Example A occnnncnncncncccnonononononononcnnnnnnnnnnnnonononnnnononananons A 2 Table 1B Drainage area soil cover complexes Example B ccccccccccccnnnnnononooonccnnncnnnnnnnnononononononaninnnnnnnos B 2 EFH2 User s Manual August 2009 Intentionally Blank yi EFH2 User s Manual August 2009 Introduction What is EFH2 EFH2 is a computer program used to predict runoff volume and peak discharge from small single subarea watersheds EFH2 predictions are based on design rainfall events associated with specific design rainfall intensity storm patterns or distributions The computational procedures used in EFH2 are described in the Natural Resources Conservation Service NRCS National Engineering Handbook Part 650 Engineering Field Handbook EFH Chapter 2 Estimating Runoff and Peak Discharge NEH 650 02 Details on the computational procedures are found in the NRCS National Engineering Handbook Part 630 Hydrology NEH 630 System Requirements EFH2 is designed to install and operate on computers with Windows 95 or later operating systems Less than MB of hard drive space is required for program install
49. shington D C NEH 630 16 United States Department of Agriculture Natural Resources Conservation Service 1989 revised 1990 and 1991 National Engineering Handbook Part 650 Engineering Field Handbook Chapter 2 Estimating Runoff and Peak Discharges Washington D C NEH 650 02 U S Department of Agriculture Natural Resources Conservation Service 2007 National Soil Survey Handbook title 430 VI Online Available http soils usda gov technical handbook Chow Ven Te editor in chief 1964 Handbook of Applied Hydrology A compendium of water resource technology McGraw Hill New York NY Kent K M A Method for Estimating Volume and Rate of Runoff in Small Watersheds 1973 United States Department of Agriculture Soil Conservation Service Technical Paper Number 149 SCS TP 149 Washington D C 21 EFH2 User s Manual August 2009 Intentionally Blank 22 EFH2 User s Manual August 2009 EFH2 Reference Guide Basic data tab EFH 2 Estimating Runoff and Peak Discharge Fie Edit View Tools Help Cy co tel el lele eos P Client State Practice By Date 68 2009 Drainage rea Aunot Curve Number Watershed Length feet Watershed Slope percent Time of Concentration hours Name of the producer participant or landowner Two letter postal code representing the State where the project is located Requires two letters Coun County where project is located May be typed in direc
50. stribution with the standard peak rate factor 484 unit hydrograph Storm Data Rainfall volume by frequency the Frequency and 24 HR Rain fields on the Rainfall Discharge data tab may be included for evaluation of up to 7 storms on the project watershed Frequency fie ds The storm frequency by return period associated with the rainfall volume entered in the 24 HR Rain column is shown here in the Frequency column if data is available from the COUNTY XX optional data file The user may enter the information here 24 HR Rain fields The 24 hour rainfall volume for the appropriate return interval indicated in the Frequency column is listed here The 24 HR Rain column is populated automatically using the COUNTY XX optional data file if one is included or may be directly entered by the user Data sources may vary depending upon when rainfall data for a particular location were last updated in the COUNTY XX file The user is encouraged to verify that the rainfall volume data are correct and appropriate for the watershed being evaluated using standard rainfall data sources Discharge data The discharge data Peak Flow and Runoff are computed when sufficient information has been entered to identify the watershed drainage area runoff curve number time of concentration and rainfall volumes for the storm or storm being evaluated Peak Flow fields Peak Flow is the maximum discharge expected to occur per storm frequency and is estimated using the
51. ted contour interval and the watershed drainage area Using this data the average watershed slope is computed using the Chow equation Average Slope Calculator AE Step 1 Measure the lengths of all the contours within the watershed boundary and sum their total Length of contours feet Contour interval feel Drainage Area actes Average Slape percent OK a Cancel Z Figure 15 Average Slope Calculator Dialog Window 14 EFH2 User s Manual August 2009 Upon exiting the Average Slope Calculator window the values for average slope and drainage area are transferred to the Basic data tab entry fields Because the maximum drainage area limitation on EFH2 is 2 000 acres a computed time of concentration will not display if an area greater than 2 000 acres is entered If the user tries to exit the Average Slope Calculator window without revising the drainage area the following warning message Figure 16 will appear advising that the drainage area entered 1s greater than 2 000 acres and the data will not be transferred to the Basic data tab Warning A Drainage area can not exceed 2000 acres DA will not be transfered to main form Figure 16 Average Slope Calculator Warning Message for drainage area entry greater than 2 000 acres Time of Concentration fie d The user may enter time of concentration directly or calculate it within EFH2 If the user determined T external to the program it may be entered direct
52. terraced C amp T poor Cont amp terraced C amp T good C amp T Crop residue poor C amp T Crop residue good Straight row SA poor Straight row SA good SA Crop residue poor SA Crop residue good Roanteured 1 naar f Acres Weighted Curve Number C Percentage Accumulated Area ac Figure 19 RCN tab Radio Buttons Radio buttons at the top of the entry screen allow the user to scroll to the desired part of the entry screen at the beginning of the Cover Description lists for each Land Use type Land use types for which cover descriptions are given are e Urban Area e Developing Urban e Cultivated Agriculture e Other Agriculture and Arid Rangeland The vertical scroll bar on the right side of the Cover descriptions and conditions allows the user to scroll down through the table entries COVER DESCRIPTION is a combination of a land use treatment class and hydrologic condition For example under the CULTIVATED AGRICULTURAL LANDS Small grain COVER DESCRIPTION there are several treatment classes listed Straight Row SR SR Crop Residue CR Contoured C C Crop Residue Cont amp terraced C amp T C amp T Crop residue with a poor and good hydrologic condition for each of the treatment classes The vertical scroll bar or land use category buttons are used to find and view specific cover descriptions Drag the scroll bar up or down to change the portion of the COVER DESCRIPTION list displayed Resi
53. ters Textural class Hydrologic soil group RG 2 EFH2 User s Manual August 2009 Rainfall Discharge Data tab Rainfall Type Frequency yrs 4 HA Rain Peak Flow lin cts Storm 1 Storm 2 Storm 43 Storm 4 Storm 5 Storm 6 Storm 7 The volume of excess precipitation in inches on the watershed not absorbed by the soil nor held Runoff on the vegetation runoff Optional rainfall data file format COUNTY XX A unique optional county rainfall data file may be created for State specific rainfall volume by frequency data to replace the sample COUNTY RF file It 1s recommended that the xx in the file name be the two letter State postal abbreviation Row Column _______ Descriptin________________ Number of return intervals included in file maximum 7 2 8 The return intervals in years County name all uppercase in quotation marks Rainfall volumes in inches corresponding to the return intervals in row 1 columns 2 through 8 Continue with as many counties as needed for your State with each county on its own row 2 row This file may be created using an ASCII editor If using an ASCII editor separate the columns by commas one space or at least one tab If the rainfall data 1s in an Excel spreadsheet use separate columns for each of the fields and save the file as a comma delimited text file The resulting text file should be checked carefully for extra characters The county rain
54. tershed is accurately represented by a single runoff curve number between 40 and 98 Watershed area is between 1 and 2000 acres Watershed hydraulic length is between 200 and 26000 feet Average watershed slope is between 0 5 and 64 percent No valley or reservoir routing is required Urban land use within the watershed does not exceed 10 Figure 2 Introduction tab The EFH2 program window consists of the menu bar the tool bar and tabbed entry screens The program initiates to the Introduction tab Figure 2 which details the limits of the program EFH2 User s Manual August 2009 EFH2 Menu Bar EFH 2 Estimating Runoff and Peak Discharge File Edit View Tools Help Figure 3 EFH2 Menu Bar The menu bar is a standard Windows feature that should be familiar to all computer users Each menu bar item Figures 4 5 6 7 and 8 has a dropdown menu with features customized for the EFH2 application The following is a description of each of the menu bar items associated dropdown menu features Menu File EFH 2 Estimating Runoff and Peak Discharge Edit View Tools Help New Ctrl h Open Fo S Recakulate Pm sala oe charge is determined by pro Print Ctrl P ng Field Handbook Chapte procedure include watershed Exit e number watershed lengt Figure 4 Menu File Menu Item Dropdown Choice Explanation File New Ctrl N Clears all data from the entry fields and resets the program for entering new project data Open
55. timating watershed time of concentration T Both average watershed slope and watershed length are needed to determine T using the lag method Obtaining this information requires some background knowledge of hydrology EFH2 User s Manual August 2009 Basic Data Files Two types of data files are used in EFH2 required files and optional files Required files The required data files are COVER TXT and TYPE RF These data files must reside in the same folder as EFH2 EXE EFH2 will not run without these required data files COVER TXT The COVER TXT file consists of the runoff curve number CN tables found in NEH 630 09 Hydrologic Soil Cover Complexes and included in NEH 650 02 These tables list CN by HSG cover type and hydrologic condition for various land use types The CN tables are used in computing a weighted CN for the watershed being evaluated The COVER TXT file must reside in the same folder as the program executable file EFH2 EXE If the COVER TXT file is not available EFH2 will not initialize and will not operate TYPE RF The TYPE RF file contains regression coefficients for peak discharge curves derived from the curves found in the NEH 650 02 exhibits for the NRCS Type I IA II and III rainfall distributions as well as a curve which can be used to determine peak discharges for the Delmarva DMV peninsula The DMV curve was derived from a combination of historical rainfall distribution and unit hydrograph data for the DMV Th
56. tly but better selected from the y dropdown list after the State has been entered Name or description of the practice for the project Initials or name of the person making the hydrologic analysis Automatically opens with the system today s date May be entered manually Drainage Area Area in acres within the watershed boundary contributing to the project site Allowable range 1 to 2000 acres Weighted NRCS curve number representing the portion of precipitation that runs off the eS land Allowable range 40 to 98 Length in feet along the flow path from the hydraulically most distant point to the project site Watershed Length Allowable range 200 to 26000 feet Average slope in percent of the all the contributing land within the watershed boundary Allowable range 0 5 to 64 percent Watershed Slope Slopes from 0 1 to 0 49 percent may be used however the user should be very cautious with such use Warning messages will be generated for slopes in the 0 1 to 0 49 percent range Time in hours for runoff to flow from the most hydraulically remote point to the project site Calculated by the program but may be manually calculated from the sum of the projected Time of Concentration flow velocities of each reach along the flow path Allowable range 0 1 to 10 hours Calculated values outside of the allowable range are reset to the nearest limit RG 1 EFH2 User s Manual August 2009 Average Slope Calculator Average Slop
57. used The COUNTY RF file is included with the installation package and contains Maryland rainfall data For users that require county rainfall data from more than one State multiple rainfall files can reside in the same folder as the EFH2 EXE file Separate State rainfall files are recommended because many States have counties with the same name A unique county rainfall file can be created using an ASCII editor and separating the columns by commas at least one space or at least one tab If the rainfall data file is created using an Excel spreadsheet use separate columns for each of the fields and save the file as a comma delimited text file The resulting text file should be checked carefully for extra characters The county rainfall file uses record formats by row and column as described in Table 1 EFH2 User s Manual August 2009 Row Column _ Description Number of return intervals included in file maximum 7 The return intervals in years County name all uppercase in quotation marks Continue with as many counties as needed for your State with each county on its own row Table 1 COUNTY RF record format Rainfall volumes in inches corresponding to the return intervals in row 1 columns 2 through 8 A portion of the rainfall data file for the State of Nebraska filename COUNTY NE is shown in Table 2 to illustrate the rainfall file format 7 ADAMS ANTELOPE ARTHUR 3 o Onl S BANN
58. zing the window to a larger window displays more lines of land cover 18 EFH2 User s Manual August 2009 Scrolling from top to bottom may be time consuming since the table is long Clicking any of the land use categories radio buttons causes the displayed portion of the COVER DESCRIPTION list to jump directly to the beginning of that category s cover descriptions The complete list of the Cover Descriptions for the Land Use category may be too long to display at one time If that 1s the case use the vertical scroll bar to scroll down and view additional cover descriptions Hydrologic Soil Groups Once the desired cover description is in view in the table enter the area in the appropriate hydrologic soil group column A B C or D Multiple hydrologic soil group entries can be made for a single cover description If the optional SOILS HG file exists it can be viewed using the Search for Hydrologic Soil Group dialog window Figure 20 to look up the hydrologic group A B C or D for various soil types Activate this file by clicking on the button labeled HGS on the toolbar See the discussion on Optional Files SOILS HG for more information on creating this file If the file is not present in the EFH2 directory clicking the HGS button brings up the window entitled Search for Hydrologic Soil Group but there are no entries in the window Search for Hydrologic Soil Group Map Unit Number and Name 6601 4 H aymond silt loam fo 35 D
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