Appendix D. SWAT Model Report

146 Pages·2014·9.66 MB·English

Appendix D.
SWAT Model Report
SWAT Model Calibration Report
for
Sandusky River Watershed
October 18, 2013
Preparedfor
EPA Region 5
Preparedby
Tetra Tech, Inc.
One Park Drive, Suite 200
Research Triangle Park, NC 27713
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Contents
SanduskyRiverWatershed.................................................................................................................1
SWATModelConfiguration.................................................................................................................5
ElevationandSlope.........................................................................................................................................5
WatershedModelSegmentation......................................................................................................................7
LandUseRepresentation.................................................................................................................................9
SoilCharacteristics........................................................................................................................................13
HydrologicResponseUnitDelineation............................................................................................................15
MeteorologicalData.......................................................................................................................................15
PointSources................................................................................................................................................17
CalibrationDataandLocations.......................................................................................................................18
SWATModelingResults....................................................................................................................20
HydrologyCalibrationandValidation..............................................................................................................20
WaterQualityCalibrationandValidation........................................................................................................23
References.........................................................................................................................................25
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Tables
Table1. IdentifiedWaterQualityImpairmentsintheSanduskyRiverWatershed.....................................4
Table2. AggregationofNLCDLandCoverClasses...............................................................................11
Table3. LandUseDistributionforSanduskyRiverWatershed(NLCD2006)........................................12
Table4. AgricultureClassSpecificityforSWATModel........................................................................12
Table5. MeteorologicalStationsfortheSanduskyRiverWatershedModel............................................15
Table6. CalibrationandValidationLocationsintheSanduskyRiverWatershed....................................18
Table7. HydrologyCalibrationCriteria.................................................................................................20
Table8. WaterBalancefortheSanduskyRiverWatershedSWATModel..............................................21
Table9. Hydrologycalibrationandvalidationsummary.........................................................................22
Table10. PerformanceTargetsforWaterQualitySimulationofMonthlyAverages(Moriasietal.,2007) 23
Table11. Waterqualitycalibrationandvalidationsummary.....................................................................24
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Figures
Figure1. SanduskyRiverWatershedLocationMap...................................................................................3
Figure2. ElevationintheSanduskyRiverWatershed................................................................................6
Figure3. ModelSegmentationfortheSanduskyRiverWatershed.............................................................8
Figure4. LanduseintheSanduskyRiverWatershed...............................................................................10
Figure5. HydrologicSoilGroupsintheSanduskyRiverWatershed(thecross-hatchedareasrepresentdual
HSGs,thatis,A/D,B/D,andC/D)............................................................................................14
Figure6. MeteorologicalStationLocationsfortheSanduskyRiverWatershed(SummaryoftheDay
Stations),USGSFlowStations,OhioEPAWaterQualityStations,HeidelbergUniversityWater
QualityStations,andprobablekarst..........................................................................................16
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Sandusky River Watershed
ThisdocumentpresentstheresultsofamodelingapproachadoptedfortheSanduskyRiverwatershedusingthe
SoilandWaterAssessmentTool(SWAT).AwatershedmodelforSanduskyRiverwatershedwasconstructed
usingSWAT2012rev591.Thewatershedmodelwascalibratedandvalidatedtoobservedflowusingseveral
USGSStations,andwaterqualitydatafromtheUSGS,OhioEPA,andHeidelbergUniversity.
QiandGrunwald(2005)havebuiltaSWATmodelfortheSanduskyRiverwatershed.Themodelwascalibrated
andvalidatedforhydrologyonlyforashorttimeframe.ThecurrentmodelbyTthasa30+yearsimulationtime-
frameanditiscalibratedandvalidatedforhydrology,sedimentandnutrients.Thepurposeofthismodelistohelp
intheestablishmentoftotalmaximumdailyloads(TMDL)forimpairedstreamsinthewatershed.
TheSanduskyRiverislocatedinnorthernOhio,westofClevelandandsoutheastofToledo,anddrainsintothe
SanduskyBayofLakeErie(Figure1).Theriverisabout125mileslong,oneofOhio’slongestwaterways,and
approximately70milesofthemainstemaredesignatedasScenicRiver.The1,827squaremileSandusky
watershedfallswithintwelvedifferentcounties,withthemajorityofthewatershedlocatedinCrawford,
Wyandot,Seneca,andSanduskyCounties.Theentirewatershedisidentifiedbythe8-digithydrologicunitcode
(HUC)04100011,andconsistsof72different12-digitHUCs.Themajortownsandcitieswithinthewatershed
includeSandusky,Bellevue,Tiffin,UpperSandusky,Bucyrus,Fremont,Clyde,Fostoria,andCarey.
ThisareaofnorthernOhioisheavilyagricultural(75%ofthelandareainthiswatershed),withonlylimitedurban
land(8%)andforestedland(8%),withsomewetlandareanearthebay.TheselacustrineareaswhereLakeErie
watermixeswithfreshriverwateryielduniquehydrologythroughlargewetlandcomplexes.Duetothelarge
amountofcropcultivation,thewaterwaysaresensitivetonutrientloading,andtiledrainsplayalargerolein
croplandhydrology.TheSanduskywatershedalsohostskarstgeologywhichresultsinsinkholesandcomplex
surface-to-groundwaterinteractions.
LakeErieisthesmallestandshallowestoftheGreatLakes.“Theshallownessofthebasinandthewarmer
temperaturesmakeitthemostbiologicallyproductiveoftheGreatLakes”(LakeErieLakeManagementPlan
[LaMP],2011).Inthe1960sand1970s,excessivephosphorusloadsfromitstributariescausedharmfulalgal
bloomsinLakeErie.Whilephosphorusloadswerereducedinthe1970sand1980sbyaddressingpointsource
discharges,excessivephosphorusconcentration,begantoreturninthe1990sandtheLakeErieecosystemis
againthreatenedbyharmfulalgalblooms(LakeErieLaMP,2009;2011).Therecentalgalbloomsarecausedby
manynew,morecomplexfactorsinadditiontonon-pointsourcetotalphosphorusloading,including:changesin
nutrientcyclingthroughthefoodwebduetotheinvasionofnonnativespecies,increasesinwatertemperatures,
andshorterandsmallericecoverageduringthewinter,andachangeintheformofphosphorusenteringthelake
(LakeErieLaMP,2011).
TheSanduskyRiveristhesecondlargestLakeErietributaryinOhio,andalongwiththeDetroitandMaumee
rivers,isoneofthethreemajortributariestoLakeEriecontributinglargephosphorusloads.TheSanduskyRiver
andothertributariestoLakeErie“containamixofnon-pointsourcepollution,includingagriculturalandurban
runoff,andpointsourcepollution,suchastreatedmunicipalsewage”(LakeErieLaMP,2011).Themore
bioavailableformofphosphorus(i.e.,orthophosphateorsolublereactivephosphorus)isfoundinsewageand
fertilizers,anditsexportmaybepromotedbythedrains(LakeErieLaMP,2011).Recentevaluationsshowthat
solublereactivephosphorusloadsareincreasingintheMaumeeandSanduskyrivers(LakeErieLaMP,2009;
2011).
TributariesintheSanduskyBasin(HUC04100011)arenotattainingtheirdesignatedaquaticlifeuses(ALUs)
duetoexcessivenutrientsandsedimentandareonOhio’s2012CleanWaterActsection303(d)list(OhioEPA
2012).TheSanduskyRiver(lower)isnotattainingitsdesignatedALUduetosedimentandisnotattainingits
designatedpublicdrinkingwatersupply(PDWS)useatthecityofFreemont’swatertreatmentplantrawwater
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intakeduetoelevatednitratelevelsfoundintheraw(i.e.,in-stream)andfinishedwater1.Thescopeofthisproject
islimitedtoimpairmentstodesignatedALUsandpublicdrinkingwateruses.Table1summarizesthewaterways
andtheirimpairments.
1ElevatednitratelevelsinthefinishedwatertriggeredthelistinginOhio’s303(d)list(OhioEPA2011,p.27).
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Figure1. SanduskyRiverWatershedLocationMap
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