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

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0.5 mi 2 , created in the merge of the data layers, weredissolved into the largest adjacent polygon.Model Parameterization(To fully comprehend the following discussion,it would be advisable to become familiar with thePRMS user’s manual [Leavesley and others, 1983]).Before using PRMS for basin simulations, it was necessaryto assign values to a wide range of parametersreflecting the various physical processes that are modeled.Definitions for PRMS parameter names are inAppendix 3. Many of the initial parameter values usedin this study were determined from an earlier USGSstudy regarding the effects of timber harvesting in theOregon Coast Range (Risley, 1994). One objective ofthat study was to regionalize PRMS parameter valuesfor use in simulating flows in nearby ungaged basins.PRMS parameters are both distributed and nondistributed.Distributed parameters contain specific valuesfor each HRU, subsurface reservoir, or ground-waterreservoir, allowing representation of varying basin surfaceconditions. In contrast to distributed parameters,nondistributed, or lumped, parameters are applied overthe entire basin.Hydrologic Response Unit-Related ParametersMany of the values assigned to HRU-relatedparameters were determined from various GIS datalayers. Area mean elevation and aspect were directlycomputed from the GIS data layers. Parameter valuesfor land-use type, cover density, and interception, forexample, were assigned by using relational tables.Some additional analysis was required to determineappropriate precipitation and temperature adjustmentsrequired for each HRU.Converting HRU data layer codes to parametervalue—PRMS uses 43 parameters to reflect HRUsurface-related physical characteristics in hydrologicprocesses. Because more than 1,000 individual HRU’swere created for the Willamette River Basin, an ArcMacro Language (AML) program (a component ofARC/INFO GIS software) was written to automatetransfer of information between the GIS data layersand attributes and the associated data tables into aformat usable by PRMS. The AML program (Appendix2) (1) assigned values of mean slope, mean elevation,and aspect for each HRU class within a specifiedbasin, (2) related data-layer attribute informationwithin each HRU class with tables of PRMS parametervalues for different attribute combinations, and (3) createdoutput files containing PRMS parameter valuesfor each HRU class in the basin.The AML program used a basin or subbasin outlinefrom a data layer that contained all the majorbasins and subbasins for the Willamette River Basin asa template to define HRU’s in each subbasin. All polygonswithin the subbasin were grouped together bytheir HRU class. The program also assigned an averageaspect value for the HRU classes that had a slopeof less than 30 percent. Assigned aspect values weredefined by an analysis of dominant aspect for each ofthe 21 major tributary basins. For slopes greater than30 percent, aspect was already given a separate aspectclassification of north, south, east, or west to accountfor the differences in snow accumulation and melt thatoccur on those different aspects.Matrix tables of basin data-layer codes and correspondingPRMS parameter values, such as those forgeology and soils (table 6) and land use (table 7),were used by the AML program to assign appropriateparameter values for the subbasin HRU’s. For example,in table 3, an HRU with a class code of “1304”represents forest land use, 5 to 30 percent slope, Tertiary-Quaternarysediments deposits, and group Csoils. The HRU class was assigned an SMAX parametervalue of 7.0 inches from table 6, and a COVDNSvalue of 0.9 (decimal percent) from table 7. Also, theAML program merged the HRU data layer with thePRISM precipitation coverage and computed a meanannual precipitation value for each HRU class in thesubbasin.The AML program creates three ASCII outputfiles containing HRU parameter values for the groups36, 37, 38 in the PRMS parameter file (Leavesley andothers, 1983). A postprocessing program is used toreformat output from these files into a PRMS inputfile. This program also assigns radiation plane values(group 14) for each HRU based on the slope and aspectcombination of the HRU.Precipitation data adjustments—Mean annualprecipitation values were derived from the annual precipitationdata layer created by PRISM. The meanannual precipitation for each HRU, as determined bythe AML program, was used to determine a precalibrationprecipitation adjustment to account for elevationand orographic differences between the input precipitationgage(s) and the HRU. Precipitation adjustmentswere computed by dividing the mean annual precipita-18
Hydrologic Response UnitsEXPLANATIONAGRICULTUREFORESTURBANPERCENTSLOPE0−5GEOLOGYTYPESedimentarySOILGROUPBPERCENTSLOPE5−30GEOLOGYTYPETertiarySOILGROUPBPERCENTSLOPE0−5GEOLOGYTYPESedimentarySOILGROUPB0−5SedimentaryC5−30VolcanicB0−5SedimentaryC0−5SedimentaryD5−30BasaltB0−5SedimentaryD5−305−305−305−305−305−30SedimentaryTertiaryVolcanicVolcanicBasaltBasaltDBBCBCMore than 30North aspectMore than 30East aspectMore than 30West aspectMore than 30South aspectVolcanicxVolcanicxVolcanicxVolcanicxBxBxBxBxFigure 7. Hydrologic response units in the Molalla River Basin, Oregon.19
Page 1: Precipitation-Runoff and Streamflow
Page 4 and 5: U.S. DEPARTMENT OF THE INTERIORBRUC
Page 6 and 7: Determining Travel Time and Dilutio
Page 8 and 9: 2. Stream-gaging stations used to c
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Page 12 and 13: network-routing models where availa
Page 14 and 15: made on the main stem at base-flow
Page 16 and 17: Figure 1. Willamette River Basin, O
Page 18 and 19: EvapotranspirationINPUTSAirtemperat
Page 20 and 21: Table 1. Climate stations used to c
Page 22 and 23: Table 2. Stream-gaging stations use
Page 24 and 25: Figure 4. Mean annual precipitation
Page 26 and 27: Major Land Use MapHydrologic Soil G
Page 30 and 31: Table 6. Geology and soils matrix o
Page 32 and 33: tion value of the HRU class by the
Page 34 and 35: Table 8. Selected monthly basinwide
Page 36 and 37: Figure 9. Location of Precipitation
Page 38 and 39: Table 11. Statistical analyses of P
Page 40 and 41: flow can become a significant compo
Page 42 and 43: diffusion at selected grid interval
Page 44 and 45: samples were collected at various d
Page 46 and 47: 3,0002,500June 21-30, 1993September
Page 48 and 49: stream network is shown on figure 1
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Page 52 and 53: 123˚22´30´´ 123˚15´ 123˚00´
Page 54 and 55: 123˚00´´ 45´30´122˚15´45˚15
Page 56 and 57: YamhillRiver123˚45´ 30´ 15´123
Page 58 and 59: 123˚07´30´´ 123˚00´ 45´ 30´
Page 60 and 61: 123˚07´30´´ 123˚00´ 45´ 30´
Page 62 and 63: 44˚15´14166000122˚07´30´´Will
Page 64 and 65: 122˚15´ 122˚00´121˚52´30´´4
Page 66 and 67: 44˚52´30´´45´122˚15´ 122˚00
Page 68 and 69: observed flow at the Willamette Riv
Page 70 and 71: DAFLOW model, and peak amplitude is
Page 72 and 73: 20DYE CONCENTRATION, IN MICROGRAMS
Page 74 and 75: ARC-INFO and Geographic Information
Page 76 and 77: WILL.WDMData-base file(Observed pre
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WILL.WDMData-base fileSWSTATSFreque
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Jobson, H.E., 1980, Comment on A ne
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APPENDIX 1. STREAM GEOMETRY FOR MAI
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APPENDIX 2. ARC MACRO LANGUAGE (AML
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APPENDIX 3. DEFINITIONS OF PARAMETE
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APPENDIX 3. DEFINITIONS OF PARAMETE
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APPENDIX 4. MEASUREMENTS USED TO DE
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APPENDIX 5. EXAMPLE PRECIPITATION-R
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APPENDIX 5. EXAMPLE PRECIPITATION-R
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APPENDIX 6. DIFFUSION ANALOGY FLOW
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APPENDIX 7. PROGRAMMING STEPS TO IN
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APPENDIX 8. PROGRAMMING STEPS TO DE
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150Climatemaxtempmintempprecipitati
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APPENDIX 10. DIRECTORY TREE AND DES
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APPENDIX 11. DIRECTORY TREES AND DE
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APPENDIX 11. DIRECTORY TREES AND DE
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APPENDIX 12. DIRECTORY FOR will.wdm
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APPENDIX 13. PROGRAMMING STEPS FOR
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APPENDIX 14. INPUT FILES FOR BRANCH
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