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Precipitation-Runoff and Streamflow-Routing Models for the ...

Precipitation-Runoff and Streamflow-Routing Models for the ...

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WILL.WDMData-base fileSWSTATSFrequency statisticsSCENARIOGENERATORANNIEFlat fileSTATSScreen/printerplotsScreen/printerplotsCorrelation <strong>and</strong>error statisticsFigure 48. Programs <strong>and</strong> files used in Diffusion Analogy Flow model post-simulation analysis. (A circledenotes a computer program, <strong>and</strong> a rectangle denotes a computer file. See Glossary <strong>for</strong> programdescriptions.)1983). After a DAFLOW simulation, <strong>the</strong> user createsa flat file from ANNIE containing a listing of observed<strong>and</strong> simulated time-series flow data <strong>for</strong> a particularstation. The column of observed data must be positionedto <strong>the</strong> left of <strong>the</strong> column of simulated data.The flat file is entered directly into <strong>the</strong> SWSTATprogram to compute error statistics.SUMMARY AND CONCLUSIONS<strong>Precipitation</strong>-runoff <strong>and</strong> streamflow-routingmodels were constructed <strong>for</strong> <strong>the</strong> Willamette RiverBasin to provide streamflow hydrographs <strong>for</strong> use inwater-quality data analysis. An instream model of <strong>the</strong>Pudding River main stem that simulated <strong>the</strong> transportof conservative constituents was used as an exampleof a water-quality application. <strong>Runoff</strong> <strong>and</strong> routingmodels described in this report can simulate streamflowat nearly 500 discrete stream locations <strong>and</strong> canoutput hydrographs <strong>for</strong> surface runoff, subsurfaceflow, <strong>and</strong> ground-water flow <strong>for</strong> 1–10 HRU classes ineach of 253 subbasins; such a capability can facilitate<strong>the</strong> assessment of water-quality data. <strong>Models</strong> that canbe run ei<strong>the</strong>r separately or toge<strong>the</strong>r to determineunsteady-state flow in a daily time step were constructed<strong>for</strong> 11 individual stream networks. To completemodeling of <strong>the</strong> Willamette River Basin, files <strong>for</strong>10 remaining networks still must be assembled usingparameter values that already have been established.The <strong>Precipitation</strong>-<strong>Runoff</strong> Modeling System(PRMS) <strong>and</strong> <strong>the</strong> Diffusion Analogy Flow Model(DAFLOW) are used in combination to simulatestreamflow at selected locations. PRMS is used todetermine <strong>the</strong> runoff response from ungaged areas, <strong>and</strong>DAFLOW is used to route flows in <strong>the</strong> WillametteRiver main stem <strong>and</strong> major tributaries. PRMS <strong>and</strong>DAFLOW use <strong>the</strong> same water data-management(WDM) file, <strong>and</strong> <strong>the</strong> systems are linked by computerscript comm<strong>and</strong>s that are transparent to <strong>the</strong> user. Theentire Willamette River system could be simulated inone model run, but this would require completing <strong>the</strong>setup of 10 remaining networks <strong>and</strong> integrating <strong>the</strong>minto <strong>the</strong> existing basin network. To improve accuracy<strong>for</strong> instream flows, most model network simulationswould use an inflow hydrograph as a starting boundarycondition <strong>and</strong> precipitation-runoff simulations <strong>for</strong>ungaged tributary inflow; however, upstream boundaryconditions also may be simulated by precipitationrunoffmodeling. All 253 model subbasins can be simulatedseparately, <strong>and</strong> flows from <strong>the</strong> individual hydrologicresponse units (HRU’s) within <strong>the</strong> subbasins canbe output separately. As a first step in water-qualitymodeling, it is envisioned that flow in small subbasins,such as <strong>the</strong> Pudding River (479 mi 2 ) or smaller tributariessuch as Zollner Creek (15 mi 2 ), will be simulatedby flow models.In this study, <strong>for</strong> each subbasin, spatial data layersof precipitation, l<strong>and</strong> use, soils, geology, <strong>and</strong> topographywere used in a geographic in<strong>for</strong>mation system to68

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