WinTR55 for Watershed Analyses
Contents
1. DER SIND ey e me 322 22 21 The Reach also needs to be entered These are not the channels described on the Te screen The Te channels are located within the sub arcas The Reach channels are the channels into which the sub areas discharge and as noted on the opening screen This sercen also asks for the receiving reach into which each reach discharges It is also possible to designate the outlet as the receiving reach as in this example This screen is also used to designate a reach as a structure reaches can be either channels or detention ponds with the appropriate routing procedure used Ifthe structure has already been described then structure name will appear on the structure name drop down menu The Reach Flow Path should be selected to confirm that the model interpreted the entered the area and reach connections correctly This sereen shows the basic watershed area conditions plus shows the reaches cach sub area lows into plus shows how the reaches are combined as they flow downstream It is possible to construct and evaluate a Very complex set sub areas for evaluation This example is about as simple as possible and still show pond and sub area hydrographs can be combined EX cech fLenaih 1000 f Area E00 CN 8 Te 922 pea area2. CN and Te screens double click on one of the cells in the columns under the d label The following screen is opened when either the area or CN column is selected The screen shows the complete listing of available land uses and surface covers for each of the 4 hydrological soil groups scrolling is needed see all the options in the area associated with each condition for each area In this example the pre development condition is woods erass combination in good condition with B soils Area 500 acres in size while Area 2 the developing area is 100 acres in size These pre development conditions are the same throughout the sub area but it is possible to select a variety of conditions and have the program automatically weight the overall CN If desire it is possible to directly enter Ihe CN value without using the calculator Although not noted in the WinTTR SS User Guide the prior TR 55 guidance recommended that the range of CNS for one area should be relatively narrow with no more than an extreme difference of 5 in the CNS for any area If the CN values varied by more than 5 it was recommended that the sub area be further divided to place the extreme values in separate sub areas This was recommended to enable more accurate routing of sub area flows compared lo using a composite CN based on a wide range of individual values The Te calculation screen can be opened in the same way by d
3. the NRCS lor Jefersan AL dick on the Return Period Rainfall Sand bunten NACE u 41 ss esse a rafal dtibuion pa fem ho lat The isi redes Ue 2078 10 pes and any ruber a rere Distribution Tes mem 7 3 100 ea Fie D Soutien ss CLASSES Cunstivcton Ste 6 28 2002 43 Figure 17 WInTR 55 storm data screen information automatically determined by location Run WinTR 55 Check seme cono gie 220 LE LE ee Figure 18 WinTR 55 event selection run screen Pert Edt TR2DRoports 85 Aerts Hel Hydrograph Peak Peak Time Table E rum peak peak Tina fale Peak and Peak Tine Qe by Rainfall Return Period wo dea2 afa Flew ENS ul BAWE is igure 19 WinTR 5S calculated hydrograph summary cree MAREM t eS Figure 20 WinfR 38 hydrograph plot cree Output Definition _ Avail Reports IF Curent dotadssorption FF stor bate I Watered Table JF Hydrogreph tae Tine Tle sueuse Sub Area Tine of Gonceirfio Sub Area Land Lee rd Curve Number Detail cach harina shue
4. B E B B E EUER EE B D ES B B E B 8 d ES pem EZ eC ESSE DESEE TT TT 4 The Te factors also changed substantially for sub area 2 after development LL 2 Time of Concentration Details uem 22 sem nem rm ee sssi 5 4 When the same 10 year storm was evaluated the following hydrograph was produced BGI ele v aec eh The upper sub area 81 had the same hydrograph characteristics but the urbanized sub area 2 had a substantial increase in runofT volume and peak flow rate The above composite hydrographs also show that the peaks are much more separated after development with the hydrograph of the developed area to develop and recede much faster than the slower responding upper area sub area The developed area now has a peak flow rate of 391 but because the hydrograph components are more separated than for pre developed conditions the overall total peak hhydrograph actually decreases slightly to about 518 cf Post Development with Pond Even though the total area peak flows are actually less after development with no pond the site development standards still required a detention pond to reduce the post development peak flow to the pre development levels for the area undergoing development The Wi
5. Urban Flow and Particulate Washoff Contributions to Discharges Ph D Dissertation Civil and Environmental Engineering Department University of Wisconsin Madison WI November 1987 Pitt R and S R Durrans Drainage of Water from Pavement Structures Alabama Dept of Transportation 253 pes September 1995 Pitt R J Lantrip Harrison C Henry and D Hue nfiliration through Disturbed Urban Soils and Compost Amended Soil Effects Runoff Quality and Quantity U S Environmental Protection Agency Water Supply and Water Resources Division National Risk Management Research Laboratory EPA 600 R 00 016 Cincinnati Ohio 231 pgs December 1999 Pit R M Lilburn S Nix SR Durrans S Burian J Voorhees and J Martinson Guidance Manual for Integrated Wet Weather Flow WWE Collection and Treatment Systems for Newly Urbanized Areas New WWF Systems U S Environmental Protection Agency 612 pgs Expected final publication in 2002 Ponce V M Engineering Hydrology Prentice Hall 640 pages 1989 SCS Urban Hydrology for Small Watersheds Technical Release 55 US Department of Agriculture Soil Conservation Service 91 pp 1975 SCS now NRCS Urban Hydrology for Small Watersheds US Dept of Agric Soil Conservation Service 156 pes 1986 SCS Time of Concentration Hydrology Technical Note No NA United States Department of Agriculture Soil Conservation Service Northeast National Technical Cente
6. 0n 100 QU2 7500 9299 739 113498 212 200 3529 850 0820 0332 120800 446 400 590014 10500 109943 10393 1361 305 1000 1700 62175 16500 13 821 1633 169200 2000 27000 70356 25500 174 861 263 29062 8075 Fie CSDosunsnts sd Drs TREE deep 7102249 ERE 4 A rating curve can also be plotted for each outlet option if the Plot option is selected on the structure screen This plot confirms that the 40 inch pipe discharge would require about 5 feet of the available po d stage FEES som in gt s Eas Ps mmu Ea i ali E i p The reach is then modified to be pond instead of a The Structure Name drop down menu in the appropriate ell is used to select the available pond name available after the accept button on the pond menu is clicked The creek data if previously on the reach data menu row for the named reach that is now a pond needs to be deleted Reach Data Je 88 emen as LLLI Jue ME Ri E ES n exe ae 9 testor corren pend sans 1032003 iz CsDocurens nd Solia Data TR Se zon sss The Reach Flow Path screen selected from that the model has the outfall reaches and areas correctly connected Flow Path Reach Flow Path Projec
7. 14 2002 SWInTI 85 is asirgle event rain elt zmallviaterdhod model The apliss to beth urban and agrtoltural areas generating hydragraphe from land areas and at selected peint cong the stream system Wut plo subareas san be modeled within a waterches though WinTR 58 has heen tested by its developers NO expressed or imple is mate ta the accuracy ard finetianing oF he program ond related preoran material rar shal he fact cf ciztrib tian any uch warrant an NO iz assured by the develpars in cannectien therewith To contact us please send email to necs usta gow Figure 12 WInTR 55 opening screen Reach Data fant Sa fgg Ring A EXE s mmo ue bo manata 502722222 22 2 Figure 14 WinTR 55 reach data screen Reach Flow Path sa T mae wit Ch e 97 Tee 0200 Bus Reaches tad ck on Outlet for mare information pose gen cow Figure 15 WInTR 55 reach flow path screen Poe ang ST mr H H Figure 16 WinTR 8S reach routing screen Stom Dato Storm Data AL NRCS To replace eve torn qata win ose cor by
8. EN z 58 e Finally the Storm Data must be selected or entered The following sereen is available under the GlobalDuta drop down main menu If the NRCS Storm Data button is selected the standard 24 hr rainfall amounts and 20 appropriate Rainfall Distribution Type are used corresponding to the county selected on the first program scr is possible to enter other rainfall amounts WinTR SS is an event model that is used for individual design storms although WinTR 55 can examine the entire set sub set of the standard storms Although the 24 hr rainfall corresponding the Te is actually used to normalize the dimensionless amounts are used the critical rain inten hydrographs Storm Data Tuscaoose Coun AL NRCS Torepisce hese tom wih those 1 far Tuscaloosa Counts AL ick on Return period conmard Eton baka Amount int NRCS Stm Date 5 34 Please selec tral lom The lel includes ho dardard 20 78 55 E spes ard ary number ol useeceimed 25 Rainfall Distribution Type EJ 100 n 36 Fils CiDocuneris ard StingevpiUDDVigpicsion Data 10 2 2002 The Run icon is then selected and the following screen appears This screen is used to select which even
9. R Pitt April 4 2005 WinTRSS for Watershed Analyses Example use of WinTRSS 1 Program Description 1 Example WinTR 55 Setup and Operation Example Applications to Construction Sites 12 Design Storms for Different Site Controls 15 The Use of Win TR 55 for Detention Pond Analyses 16 Predevelopment Conditions 16 Post Development Conditions 25 Post Development with Pond 28 Summary 34 Important Internet Links 35 References as Example use of WinTRS5 The following discussion is summarized from the WinTR 55 user guide information while the example uses the previously deseribed information WinTR 55 work group was formed in the spring of 1998 to modernize and revise TR SS and the computer software The current changes include upgrading the source code to Visual Basic changing the philosophy of data input developing a Windows interface and output post processor enhancing the hydrograph generation capability of the software and flood routing hydrographs through stream reaches and reservoirs The availability and technical capabilities of the personal computer have significantly changed the philosophy of problem solving for the engineer Computer availability eliminated the need for TR 55 manual methods thus the manual portions graphs and tables of the user document have been eliminated as official guidance The Win TR SS user manual NRCS 2002a covers the procedures used in and the operation of the WinTR SS comp
10. ated models should be se l also be emphasized ar WinTR 55 and TR 20 are not models fr water quii evaluation The curve member approach not applicable he sized ha reponse forth vast majority of pollutant discharges continuous simulations fr long periods needed e understand he complex behavior polan discharge under a wide range condo an pari rang including scour from shallow and dry ponds s needed to predict the level of pollutant control that may be achieved in detention ponds However multiple tools can be used together to better understand how multiple and often times conflicting objectives can be met Important Internet Links Alabama Rainfall Atlas http bama ed ai WinTR 55 computer program windows beta version wiww wee nrcs usd gov hydro bydro tools models wintrS S html TR SS 1986 documentation ores usda gov downloads bydrology hydraulics 55 58 pd TR20 computer program new windows beta version gov bydro bydro tools models wintr20 html National Engineering Handbook Part 630 HYDROLOGY http wan wee ntes usda gov hydro bydro techref neh 630 html US Army Corps of Engineers Hydrologic Management System User Guide HEC replacement for 1 http www hee usace army millsoftware Ber hms hechms hechms html US Army Corps of Enginee
11. d permanent pool elevation to outlet invert plus 1 2 diameter This estimation of head coupled with a slightly different orifice Dow coefficient 0 6 instead of 0 8 essentially cancel each other out and the result is higher discharge estimate for one type of pipe material versus slightly lower discharge estimate for another The pipe materials checked were reinforced concrete and corrugated metal Overall the estimated differences were very small The future version of the User Manual will be rewritten to reflect this short tube flow assumption with a disclaimer if the user needs more exact estimate they should use a different tool SITES or a user stimated rating in TR 20 They also stated that Version 1 0 of WinTR SS will keep the existing short ube approximation for pipe outlets of structures A future version 2 0 of WinTR 55 will likely have the ability to enter a user provided Sage storage discharge rating curve or more complete pipe rating curves WinTR 55 is a great improvement over the older TR SS in that more accurate channel and reservoir routing is provided This Windows version of the program is also very easy to use and the provided graphical output options enable efficient and rapid evaluations This simple example is comprised of two subwatersheds a 500 undeveloped area and an adjacent 100 developing area Specific characteristics of these areas soils land use breakdowns channel characteristics et are provided i
12. drograph summation Figure 10 is a diagram showing the WinTR SS model its relationship 1o TR 20 and the files associated with the model TR 55 System gt gt Program Flow Figure 10 WIRTR 55 system schematic NRCS 20022 Capabilities and Limitations WinTR 55 hydrology has the capability to analyze watersheds that meet the criteria listed in Table 9 Model Input The various data used in the WinTR 55 procedures are user entered via series of input windows in the model A description of each of the input windows follows the figure Data entry is needed only on the windows that are applicable to the watershed being evaluated Minimum Data Requirements While WinTR 55 can be used for watersheds with up to ten sub areas and up to ten reaches the simplest run involves only a single sub area Data required for a single sub area run can be entered on the TR 55 Main Window These data include Identification Data User State County Project and Subitle Dimensionless Unit Hydrograph Storm Data Rainfall Distribution and Subarea Data The subarea data can be entered directly into the Subarea Entry and Summary table Subarea name subarea description subarea flows to reach outlet area runoff curve number CN and time of concentration T Detailed information for the subarea CN and T can be entered here or on other windows if detailed information is entered elsewhere the comp
13. frequency and associated 24 hr rain total appropriate for The design storms range from 4 0 to 8 4 inches in depth and the times of concentration range from 1 5 to 30 n The design rain intensities could be very large for some of these design elements Table 12 Example Acceptable Levels of Protection for Different Site Activities Site Construction Control Acceptable Failure Rate Design Storm 24hrRain Depth during Site Construction Return Period Associated with this tivities years Design Storm Return Period Dern 257 s 55 channel E 2 88 Site slopes 10 10 Sie fences E 19 40 Sediment pond Sand 1 2050100 6 Downsicpe pefmeterhlerfences 10 60 The Use of WinTR 55 for Detention Pond Analyses This example application of Win TR 55 demonstrates the use of this new program in evaluating detention ponds in watershed with multiple subdrainage areas As noted in the User Guide Win TR 55 has some limitations compared to the more comprehensive TR 20 program In the analysis of detention ponds structures the most important limitation is the availability of only 3 types of outlet structures broad crested weir a 90 and pipe The greatest concern is ow the pipe outlet is considered short tube approximation approach The USDA WinTR 55 team explained this as follows This approximation uses the pipe diameter and the head on the pipe as the total hea
14. fs inthe developing watershed The upland sub area peak flow was about 453 cfs while these combined to create total basin peak flow of about 522 Cle aie EAR 4 Post Development Conditions The pre development file was edited and re saved using the save as option under the drop down menu to reflect developed conditions in sub area 2 as shown on the following screens Fi colors 4640 pun Pub gus Im gt WinTR 55 Small Watershed Hydrology Pop ilo aa Une enr E KES are Suttle meonDato SomDassoure Con ORES Saas is Fa rblbierturonlimiti iara trt sn Suni ETE x Giorn me bares tescipion ees m r Sj smn pen pom and Sein TRANS SDF The developed 100 acre sub area is comprised of 25 acres of commercial 25 acres of town houses and 50 acres of 1 3 acre lot residential areas notice that he individual CNs range from 72 to 92 much broader than a difference of 5 Therefore this area should be further sub divided to separate the individual land uses if possible They were not in this example though 26 Eg T 3 e es Land Use Details Al ETT ere Tix i pte n B B
15. han if the water was not detained el sure sel poem es ch Rane Sg GEE TET FETE This example illustrated how a detention pond can be evaluated for a developing area how it can be designed for multiple objectives and how these objectives may or may not be realized in a watershed The simple application of detention pond standards may not always provide the desired downstream benefits A basin wide hydrologic analysis the above example was a crude and simple example is needed to ensure that ponds area sized and located correctly to provide the desired benefits Obviously the above example was a setup to illustrate this issue However it would be relatively easy to modify the pond to stil provide the desired water quality benefits while not exasperating the flood control objective A change in the pond spillway device to allow the pond to empty more rapidly would solve this problem In most eases detention ponds providing large amounts of storage for flood control should be located in upper reaches of watersheds to lessen these problems Summa WISTR SU is probably tio simples and cheapest model Bat can be used to examin asin id iral aus Mia evel simple tod i based conveniant drainage design procedures Future improvement ia the option Will make it more accurate I more prece analyses needed TR 20 or nore sophistic
16. least 3 feet deep of 1 78 acres A value of 2 acres will therefore be used If this portion of the pond is 6 5 feet deep and the top area is 3 5 acres the pond side slopes would be about 73 1 reasonable value to provide about 17 6 acre feet of storage The first step was o describe the pond and to edit post development file to change Reach from a channel to a pond The following is the description of the pond structure using he Structure Data top menu bar option The pond surface areas ate described using the above calculated estimates The area is 2 acres at the depth where the discharge begins and is 3 5 acres in area 6 5 fet above this spillway elevation WinTR S5 will assume a deeper pond as needed above 65 feet but will use side slope Ifthe upper area was not entered t is an optional value the pond is assumed to then have vertical side slopes not a good idea The Discharge Description is based on the spillvay type selected a pipe using the pipe approach previously described weir Ifa weir is Selected it can be a broad rested weir and the weir length entered ra value is entered for the weir length the model will assume a 90 V notch weir Ia pipe spillway is selected as in this example the pipe diameter in inches is given ranging from 6 to 60 inches When a pipe is selected he height from the invert ofthe discharge end ofthe pipe to the spillway elevation is also needed f
17. n the following discussion Initially the pre development conditions are examined followed by developed conditions preliminary design of a detention pond is then evaluated to attempt to provide similar discharge peak flows from the developed watershed portion after development as before development Predevelopment Conditions The following screen shows the basic site conditions The sercen also shows the location of the area Tuscaloosa County Alabama the selection of the standard dimensionless hydrograph the selection of the area units and labels The drop down options menu was also used to select English units actually US customary units The area CN and Te values area entered and calculated in other screens and the information was automatically transferred to this sereen Ti ProptOnts mv Heb r els lic WinTR 55 Small Watershed Hydrology Mion Data iens ccc Go El 2020 Se ue Tirsas Cay AL ES btan ets Tyre 1 Sba eng a gy ees eese eem ETE m Peor Ve 00 9 ims 600 e Tose aE OT OE In order to enter the area
18. n io Peak fou rate and 04 mo 2 n ste stream hydrograph be combined wilh U and Ua u Upslape diversion io Peak fou rate and 24 mio mo m n ste stream yirograph combined wih U and U2 or O Te drainage Peak rale and TET ss sediment pond and hydrograph main ste steam also Slope protection needed On site drainage lo Peak ow rate and 18 fier fence and main hydrogmph steam asc Peak flow rate and perimeter fer fence hydrogragh so slope Protection needed Onsite towards Peak ow rate and perimeter filer fence hydrogrh so slope proecion needed os Onsite towards Peak ow rate and 18 ow perimeter tr fence hydrogragh so slope proecion needed On ste nothing wil 13 mom remain undisturbed or Onsite nothing wll ma 0 mom remain undisturbed Design Storms for Different Site Controls All of the information needed to calculate the expected flows from these upslope and on site areas is shown on Table 12 except for the design storm The area has SCS type rain distribution and the construction period will be one year The different site features will require different design storms due to the different levels of protection that are appropriate Table 12 lists the features and the assumed acceptable failure rates during this one ye period along with the corresponding design storm
19. nTR SS suggests a simplified approach to size the needed pond based on the difference in the volumes for pre and postalevelopment conditions and restricting the pond outlet device tw the pre development flow The WisTR 20 Reports lists the depth in watershed inches The pre development runoff was reported to be 1 95 inches over 100 acres This corresponds to about 16 2 acre feet The post development runoff depth was about 4 05 inches also over the same 100 acres corresponding to about 33 8 acre feet The difference and required pond storage is therefore 17 6 acre feet The maximum pond discharge was the pre development peak flow for the 10 year storm for this example of 139 The pond size can then be erudely sized using these values However this was to be a multi purpose pond also providing water quality benefits A rough guide for the pond surface area the bottom of the storage layer for water quality benefits can be estimated to be about 3 of the watershed paved area plus 0 5 of the watershed pervious arca The CN menu presented the watershed imperiousness areas for each development category The commercial arca is assumed to have 85 impervious area the high density residential area to have 65 imperviousness and the Tow density residential area to have 30 imperviousness A simple calculation resulted in pond bottom arca the actual surface of the permanent pool which needs to be at
20. or the simplified equation This height must be at least twice the diameter of the pipe Up to three pipe diameters or weir lengths be entered The model will evaluate all three options making the selection of the choice easier As the dimensions are entered the rating curves flow vs height and strage below the elevations are displayed This is a good indication of the correct spillway size the maximum discharge close to he desired pond depth can be observed In this case the 40 inch pipe has the desired discharge of 139 ef at a stage slightly above 4 feet and well under 10 fet The 36 inch pipe option would need about 10 feet of stage greater than planned while the 24 inch pipe would even more more than 20 f Therefore itis expected that the 3 pipe option the 40 inch pipe would work best 29 inis Structure Structure Data Pond Surface accept esos gt aw z pol corel Discharge Description ples Type per pe en oy Orifice flow essumed Pipe Flow Rating Urban pond Dianetert 24in Diameter Dianeterd 4 Tempora Stage PipeHead Flow PipeHead PpeHead Flow Stuage si LI dhs umo 000 one
21. ouble clicking on any cell under the Te column I available the Te can be directly entered without using the calculator The following screens show the examples for sub areas 1 and 2 selected by using the drop down option under sub area name The flow path described on the screens needs to be pre determined to be the critical Te flow path the path that requires the longest time for water drainage not the physically longest flow path necessarily As in TR SS the Te can be comprised of three components The sheet flow length is now restricted to a maximum length of 100 fL Prior TR S5 guidance allowed a maximum length of 300 but this was thought to be excessive by the Win TR 55 development team The Surface Manning s menu lists the available sheetflow roughness values These are substantially different than what would be appropriate for channel low conditions for roughe material Smooth surfaces have similar values The shallow concentrated flow surface drop down options are restricted to paved and unpaved Two shallow concentrated flow segments are allowed There are also two channel segments allowed These are usually designated as streams on USGS topographic maps ee as Time of Concentration Details 99 amnion a rove T MS Se OT rre ses 222200002 Pent Time of Concentration Details e
22. r 12 pp 1986 Thronson R E Comparative Costs of Erosion and Sediment Control Construction Activities U S Environmental Protection Agency EPA4309 73 016 Washington D C 1973 Welle P L Woodward D E Fox Moody 4 Dimensionless Unit Hydrograph for the Delmarva Peninsula Paper No 80 2013 ASAE 1980 Summer Meeting 18 pp 1980 36
23. rs River Analysis System User Guide for water surface profile calculations HEC RAS replacement for HEC 2 http wanw hee usace army milisoftware hec ras hecras hecras html References Chow V T Maidment D R and Mays L W Applied Hydrology MeGraw Hill S86 pages 1988 HEC HEC RAS User s Manual Version 2 0 US Army Corps of Engineers Hydrologic Engineering Center April 1997 Illinois Procedures and Standards for Urban Soil Erosion and Sedimentation Control Association of Illinois Soil and Water Conservation Districts Springfield IL 62703 1989 Maidment D R ed Handbook of Hydrology McGraw Hill 1422 pages 1993 MoGee T J Water Supply and Sewerage McGraw Hill New York 1991 NRCS National Engineering Handbook 630 HYDROLOGY downloaded June 23 2002 gov wateruality common neh 304content htl NRCS SITES Water Resource Site Analysis Computer Program User s Guide United States Department of Agriculture Natural Resources Conservation Service 469 pp 2001 NRCS HinTR 55 User Manual US Dept of Agriculture Natural Resources Conservation Service Downloaded June 23 2002 from gov waterquality commowtrSS tS5 heta html Version dated April 23 20022 NRCS TR 20 System User Documentation United States Department of Agriculture Natural Resources Conservation Service 105 pp 20028 draf Pit R Small Storm
24. t multiple area example Flow Path Reach A Length 1000 f1 Area 1 Area 500 ac CN 58 Te 922 Reach B StrueturezUrbon pond Area 2 Area 100 a0 CN 80 Te 154 Blue Reaches Green Subareas Red Structures gt EET E com Click Outlet for more informa Data drop down menu can also be selected to ensure Upon program execution the data can be reviewed to verify if any of the spillway options were suitable The following table shows that trial 3 the 40 inch pipe reduces the reach influent flow 391 down to about 130 fs close enough to the desired maximum peak flow Unfortunately the outfall peak flow is shown to be about 580 fs substantially greater than the predevelopment peak flow of 521 cfs and the post development peak with no pond of 518 Pa WITS Fl Hydrograph Peak Peak Time Table ost development sath pond Pesk teak Table trial D Je Flew Desh Balen Period E Decks nd Sesion Da lc 4 The following plot of the reach hydrographs indicate how this occurred The water from subarea 2 was delayed in the detention pond Reach B and was discharged so that its peak rate closely coincided in time with the undeveloped hydrograph from subarea 1 Reach A causing a larger peak flow t
25. t s are to be evaluated 220 Tto When the Run button is selected after clicking on cach desired rain the program calculates the site runofrand routes through each reach An embedded version of TR 20 is actually used to conduct the analyses being much better than the prior manual TR SS procedures which required rather crude increments of important site factors The following screen is then automatically displayed after a run This screen displays the TR 20 output screen showing the peak runoff conditions and times It is also possible to select WinTR 20 Reports for more detailed output information ial ip xd us Hydrograph Peak Peak Time Table Uam aR The Output Definition or report writer icon displays the following screen This allows specific information to the produced in a written report displayed on the computer screen The following is an on sereen report Wei Eh WIRE Multiple WinTR 55 Reports 2 The following is the hydrograph that be plotted by selecting the next to last icon on the top tool bar The selection screen allows different hydrographs to be displayed This plot shows how the pre development hydrographs from the two sub areas join for the complete hydrograph The 10 year storm having a 10 chance of occurring in any one year produces peak flow of about 139 c
26. ude filer fencing along the project perimeter or sediment ponds depending on flow conditions These controls must be completed before any on site construction is started Determination of upland flows coming towards the disturbed areas These flows must be diverted by svales or dikes or safely carried through the construction sites Channel design will be based on the expected flow conditions These controls must be completed after the downstream controls and before any on site controls are started Determination of on site flows on slopes going towards filter fencing sediment ponds or other controls Needed to also evaluate shear stress on channels and on slopes Figure 25 is an example site regional map drawn on a USGS quadrangle showing a construction site and associated upland and downslope drainages The previous discussion illustrated how it is possible to easily ealeulate the runoff characteristics affecting the site and downslope areas for different rain conditions In addition detailed site conditions for different project phases can also be evaluated for the design of appropriate erosion and sediment controls Table 11 Upslopo and On Site Subdrainage Area Characteristics for Construction Site Are Location Objective An Covern Average Te Notation acres min path slope vr papa Hysmpaph Ta BE 3715 01 se steam combined win U2 and U3 v2 Upsiope diversio
27. une Siete pal ng seat s es Figure 21 WinTR 55 report generation screen Fr Lond Use Details poc ms o os Structure Data a are nil pd xxu rs ir Tide mut f War fuum TE igure 24 WinTR 55 structure dala sereen for detention facilia This Win TR S5 example resulted in a peak flow for the 2 storm of about 730 compared to the previously calculated value of 910 This difference is due to the different routing procedure used plus the more precise hydrograph development procedure in the updated WinTR S5 version compared to the tabular hydrograph method Example Applications 0 Construction Sites The following example outlines the hydrographic information needs and how they ean be determined using WinTR 55 fora small urban area in case a construction site There are number of situations where WinTR SS or TR 55 can be used to advantage when evaluating construction sites including the design of erosion and sediment controls These may include Determination of flows going away from the site affecting downstream areas Downstream erosion controls may incl
28. using the CN approach Sub Area Watershed Area Figure 11 Sample Watershed Schematic NRCS 20022 Table 10 Sample Watershed Flows NRCS 2002 Flows into Reach Upstream End of Reach A Reach Reach Reach Reach C Reach Reach D Reach Reach E Reach E OUTLET Reach D OUTLET Reaches define flow paths through the watershed to its outlet Each subarea and reach contributes flow to the upstream end of a receiving reach or to the Outlet Accumulated from all sub areas routed through the watershed reach system by definition is flow at the watershed outlet Processes WinTR 55 relies on the TR 20 model for all hydrograph processes These include hydrograph generation combining hydrographs channel routing and structure routing The program now uses Muskingum Cunge method of channel routing Chow etal 1988 Maidment 1993 Ponce 1989 The storage indication method NRCS Part 630 Chapter 17 is used to route structure hydrographs Example WinTR SS Setup and Operation An application using WinTR 55 and an urban watershed example is shown on Figures 12 through 21 Figures 22 and 23 are other screens available in WinTR 55 that can be used to aid in the calculation of some of the site data while Figure 24 is used for detention facilities structures mmm WinTR 55 Small Watershed Hydrology Window Based Application version 2002 0017 Compiled on 04
29. utational results are displayed in this window Watershed Subareas and Reaches To properly route stream flow to the watershed outlet the user must understand how WinTR 55 relates watershed subareas and stream reaches Figure 11 and Table 10 show a typical watershed with multiple sub areas and reaches Table 9 WinTR 55 Capabilities and Limitations NRCS 2002a Varia mis Mesum sur G SESE TT E TET However carefully examine results rom subareas less than 1 LEE square Ries SITE Naber SW SET Nomber of reaches 3 Types of reaches Tana rm Resch Hoang Muskingur Routh Sirage Stucurs Types or War Tl Ser 32 Renal Dept 9530 inches 21 270 mm NRCS LIA 1 TI NGO ar inse defines Fascia Data Dimensionless UST FIG Standard Peak E EEE EH ET Delmarva see Example 3 EZEL Tough ro mira rai dep by We NOS ta above table Tus be TEE Wal We SCS cave umber methods incorporated in s newer version are accurate for sma storms I moet cases larger stor used for drainage design are reasonably sued to this method Pit 1987 and a al 2002 showed that depths less than 2 or 3 inches can have significant errs when
30. uter program Part 630 of the Natural Resources Conservation Service NRCS National Engineering Handbook provides detailed information on NRCS hydrology and isthe technical reference for WinTR 55 Program Deseription WinTR 55 is single event rainfal runofT small watershed hydrologic model The model generates hydrographs from both urban and agricultural arcas and at selected points along the stream system Hydrographs are routed downstream through channels and or reservoirs Multiple sub areas can be modeled within the watershed Model Overview watershed is composed of subareas land areas and reaches major flow paths in the watershed Each subarea has hydrograph generated from the land area based on the land and climate characteristics provided Reaches can be designated as either channel reaches where hydrographs are routed based on physical reach characteristics or as storage reaches where hydrographs are routed through a reservoir based on temporary storage and outlet Characteristics Hydrographs from sub areas and reaches are combined as needed to accumulate flow as water moves from the upland areas down through the watershed reach network The accumulation of all runoff from the watershed is represented at the watershed outlet Up to ten sub arcas and ten reaches may be included in the watershed WinTR 55 uses the TR 20 NRCS 20026 model for all of the hydrograph procedures generation channel rutin storage routing and hy
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