ConfiguringandRunningtheSWATModelWrittenbyLauraBriley,2010UniversityofMichigan/NOAA/CIRES

TableofContents

CONFIGURINGANDRUNNINGTHESWATMODEL 1BACKGROUND 11. SOFTWARE:MWSWAT 12. DELINEATEWATERSHED 23. CREATEHYDROLOGICALRESPONSEUNITS(HRUS) 34. SWATSETUP 3A. WEATHERSOURCES 4B. RAINFALL/RUNOFF/ROUTING 4C. RAINFALLDISTRIBUTION 5D. POTENTIALETMETHOD 5E. CRACKFLOW 5F. CHANNELWATERROUTINGMETHOD 5G. CHANNELDIMENSIONS 5H. STREAMWATERQUALITYPROCESSES 55. WRITESWATINPUTFILES 56. RUNSWAT 67. HELPFULRESOURCES 6

BackgroundTheSoilWaterandAssessmentTool(SWAT)isveryeasytorunifalloftheinputfilesarepreparedproperly.TheDataPre‐ProcessingforSWATdocumentgivesinstructionforpreparingyourdata,butthesearenottheinputfilesforSWAT.ForofficialdocumentationofSWATinput/outputfiles,seehttp://swatmodel.tamu.edu/documentation.Thereisaplug‐intoMapWindowthatwillcreatethenecessaryfilesforyoubyusingthepre‐processeddata.Thisdocumentdemonstrateshowtoutilizethissoftware,MWSWAT,inordertorunSWAT.

1. Software:MWSWATDownloadMWSWATandinstallinthedefaultlocation(C:\ProgramFiles\MapWindow\Plugins\MWSWAT)http://waterbase.orgThepresentversionofMWSWATincludesthe2005versionofSWATbutlaterversionsofSWATareavailableandmaybeinstalledinitsplaceiftheuserchoosesthisoption.

2. DelineateWatershedStartMapWindowandundertheplug‐inswindowturnontheMWSWATandWatershedDelineationoptions.MapWindowmayneedtoberestartedinorderforthemtoappearacrossthetoptoolbar.SelecttheMWSWATplug‐ininthetoptoolbar.Thefollowingboxshouldopen:

Select“NewProject”andcreateanamefortheproject.ThiswillcreateanewfolderinthedirectorynamedafterthenewprojectaswellasaMapWindowprojectfile.TheMWSWATinterfacewilldirectyouthroughthedataprocessingsteps.SelectStep1:DelineateWatershedandpullupyourclippedDEMfilecreatedearlier.Thenselect“ProcessDEM”.ThiswillplaceyourDEMinthenewmapwindowandanewprocessingframewillappear:

ThefirstsectionofoptionsallowsyoutospecifytheDEMlayeranditscharacteristics.EitheruseCurrentViewExtentsforthemaskorcancelUseaFocusMask.Note:makesurethatallthelayersyouthroughouttheprocessareofthesameprojection.Click“Run”forthetopsection.Thesecondsectionconsistsofdefiningthenetworkdelineationusingthethresholdmethod.Thisisthethresholdinareaunitsflowingintoagivenpointbeforeitis

designatedasastream.Thelowerthenumber,themorestreamsandsub‐basinswillbecreated*.Oncedefined,select“Run”.Lastly,youmusteitherselectaninlet/outletfileorcreateanewone.Ifcreatinganewone,firstzoomintotheDEMregionwherethestreamscrosstheboundaryofyourregion(forexample,watershed).Thenselect“DrawInlets/Outlets”.Nameyournewfileandthenclickonthemapwherethestreamsenter(exit)yourregionanddefinethemasinlets(outlets).Runthefinalsection.Attheendofdelineatingthewatershed,yourmapwindowwilllooksimilarto:

3. CreateHydrologicalResponseUnits(HRUs)*Select“CreateHRUs”.Anewwindowwillappearwhereyouwilluploadyourlandusedataandsoildata.IfusingthedataprovidedonWaterbase.org,youmayusethetablesglobal_landusesandglobal_soils.Ifusingdatathatdoesnotfollowthesetableassignments,pleaseseepage64oftheMapWindowInterfaceforSWATdocument:http://www.waterbase.org/documents.htmlOncethetablesareselected,“Read”thedata.YouwillnoticemanydropdownmenusandoptionsavailablewhencreatingtheHRUs.Youmayreadinmoredetailabouttheseoptionsinthedocumentlistedabove.Seesection5.2ofthedocumentforadditionalhelp.Afterallofyourselectionsaremade,“Create[the]HRUs”.

4. SWATSetupThelaststagebeforerunningSWATistodefineafewmoreselectionsforthevariousoptionsoffered.Firstdefinethetimeframeofthesimulation.Next,underWeatherSources,select“Choose”.

MWSWAThasatemplatedatabasethatistheinitialdatabaseforallnewprojects.Thisdatabasehasbuiltinweatherstationdatathatmaybeusedbyselecting“Databasetables”andweather_sourcesinthedropdown.Formeasuredweatherdata(precipitation[.pcp],temperature[.tmp],solarradiation[.slr],wind[.wnd],andhumidity[.hmd])itispossibletoeithereditthetablesinthedatabaseorreadinthetextfilescreatedintheSWATPreProcessingdocument.

a. WeatherSourcesi. ImportingYourDataInthe“ChooseSWATweathersources”window,selecttousealocalfileanduploadthestationfileyoucreated.ThisselectionindicatesthatyouwillusedatainthemodelrunandMWSWATwillgolinebylinethroughthestationfileandfindtheassociateddatafilesandcondensethem.Forexample,.pcpfileswillbecondensedintopcp1.pcp.Upto6stationswillbeincludedinonepcp1.pcpfileandremainderswillbeinpcp2.pcp,pcpn.pcp.

ii. TheWeatherGeneratorTheweathergeneratorfillsinanygapsinyourmeasuredweatherdataoritmaybeusedifyoudonothaveanyweatherdata.EachnewMWSWATprojectissuppliedwithaweathergeneratortablefortheUSandmaybeusedifyourwatershediswithintheUS.

iii. Select“Done”onceyourweathersourcesarechosen.

b. Rainfall/Runoff/Routingi. Runoff

1. RunoffCurveNumber(CN)isanempiricalparameterusedforpredictingdirectrunofforinfiltrationfromexcessrainfall.1

2. GreenandAmpt(G&A)assumewaterinfiltratesdrysoilasasharpwettingfront.2

1http://en.wikipedia.org/wiki/Runoff_curve_number2http://www.alanasmith.com/theory‐Calculating‐Effective‐Rainfall‐The‐Green‐Ampt‐Method.htm

c. RainfallDistributionUsedtogeneratedailyprecipitationvalues.

i. Skewednormalii. Mixedexponential

d. PotentialETMethodi. Priestley‐Tayloris“anempiricalapproximationofthePenmancombinationequation…toeliminatetheneedforinputdataotherthanradiation.“3

ii. Penman‐Monteithisan“equation[that]requiresdailymeantemperature,windspeed,relativehumidity,andsolarradiationtopredictnetevapotranspiration.”4

iii. Hargreavesisusefulwhen“estimatingETinsituationswheredatabanksarelimitedandonlymaximumandminimumairtemperaturedataareavailable.”5

iv. Readin

e. CrackFlowi. ThisisanewfeaturetoSWATandhashadlimitedtesting.ItshouldonlybeactivatedonsoilsclassifiedasVertisols.

f. ChannelWaterRoutingMethodi. Variablestoragecausestheoutflowvolumetobeafunctionofthestoragecoefficient,volumeflowingin,andthevolumestored.6

ii. Muskingummethodconsidersalinearchangeindepthalongthereach.7

g. ChannelDimensions i. Thisisanew(andundertested)featureofSWATthatallowschanneldimensionstobeupdatedasaresultofdegradation.Itisrecommendedtokeepdimensionsconstant.

h. StreamWaterQualityProcessesi. Ifturnedon,in‐streamtransformationsofnutrientsandpesticidesareallowed.

5. WriteSWATInputFilesa. Oncealloftheoptionshavebeenconfigured,checkthe“Writeallfiles”box

andthen“Writefiles”.

3http://www.civil.uwaterloo.ca/watflood/Manual/02_03_1.htm4http://en.wikipedia.org/wiki/Penman‐Monteith5HydrologyhandbookByAmericanSocietyofCivilEngineers.TaskCommitteeonHydrologyHandbook6www.brc.tamus.edu/swat/.../ChannelSedimentPositionPaper.pdf7DesignhydrologyandsedimentologyforsmallcatchmentsByCharlesThomasHaan

b. AwindowwillappearifyourwatershedisintheUSaskingforplantgrowthheatunits.ValuesareprovidedforUSregions.Ifyouwishtouseadefaultvalue,thiswillhavetobeobtainedelsewhere.

6. RunSWATa. Afterthemessageappearsthatyourfileshavebeenwritten,“RunSWAT”and

saveyourrun.

7. HelpfulResourcesMapWindowInterfaceforSWATWaterBase:SWATinanopensourceGIShttp://www.waterbase.org/documents.html