COVERCONTENTSFIGURESTABLESCONVERSION FACTORSGLOSSARYABSTRACTINTRODUCTIONBackgroundPurpose and ScopeApproachStudy Area DescriptionFigure 1. Willamette River Basin, Oregon.AcknowledgmentsPRECIPITATION-RUNOFF MODELSDescription of Precipitation-Runoff Modeling SystemFigure 2. Flow diagram of the Precipitation-Runoff Modeling System conceptual model.Time-Series DataTable 1. Climate stations used to collect data for input to precipitation-runoff and streamflow-routing...Figure 3. Location of climatological and hydrological stations in the Willamette River Basin, Oregon...Table 2. Stream-gaging stations used to collect data for input to precipitation-runoff and streamflow...Delineation of Basin Physical CharacteristicsTable 3. Basin spatial-coverage categories and corre- sponding data-layer codes used to create hy...Figure 4. Mean annual precipitation in the Willamette River Basin, Oregon, 1961–90...Figure 5. Major drainage basins of the Willamette River Basin, Oregon.Figure 6. Major land use, slope and aspect, geology, and soils in the Molalla River Basin, Oregon.Table 4. Definition of geologic assemblages in the Willamette River Basin, Oregon, grouped accord...Table 5. Definitions of soil groups in the Willamette River Basin, OregonFigure 7. Hydrologic response units in the Molalla River Basin, Oregon.Model ParameterizationTable 6. Geology and soils matrix of basin data-layer codes and corresponding Precipitation-Runof...Table 7. Land-use matrix of basin data-layer codes and corresponding Precipitation-Runoff Modelin...Figure 8. Temperature stations used to define monthly lapse rates as an increment of elevation, Wi...Table 8. Selected monthly basinwide (nondistributed) calibration-parameter values for Precipitation...Table 9. Optimized Precipitation-Runoff Modeling System parameter values for 10 individual calibra...Model Calibration and VerificationFigure 9. Location of Precipitation-Runoff Modeling System calibration basins, Willamette River Bas...Table 10. Additional distributed and nondistributed Precipitation-Runoff Modeling System calibratio...Table 11. Statistical analyses of Precipitation-Runoff Modeling System calibration and verification...Figure 10. Observed and Precipitation-Runoff Modeling System (PRMS) simulated discharge for...Figure 11. Typical simulated flow-separation output from the Precipitation-Runoff Modeling System...Table 12. Statistical analyses of combined Precipitation-Runoff Modeling System and Diffusion...STREAMFLOW-ROUTING MODELSDescription of Diffusion Analogy Flow ModelChannel Reach DelineationModel ParameterizationFigure 12. Typical area-discharge relation developed from time-of-travel data, stream-gaging-station...Special Studies to Document Low FlowFigure 13. Location of time-of-travel and gain-loss studies, Willamette River Basin, Oregon.Figure 14. Ground-water gains from and losses to the Willamette River from Eugene to Willamette F...NETWORK-ROUTING APPLICATIONSTributary NetworksFigure 15. Johnson Creek Basin, Oregon, and schematic diagram of the stream network.Figure 16. Observed and simulated discharge from combined Precipitation-Runoff Modeling System...Figure 17. Clackamas River Basin, Oregon, and schematic diagram of the stream network.Figure 18. Observed and simulated discharge from combined Precipitation-Runoff Modeling System...Figure 19. Tualatin River Basin, Oregon, and schematic diagram of the stream network.Figure 20. Observed and simulated discharge from combined Precipitation-Runoff Modeling System...Figure 21. Molalla River Basin, Oregon, and schematic diagram of the stream network.Figure 22. Observed and simulated discharge from combined Precipitation-Runoff Modeling System...Figure 23. Yamhill River Basin, Oregon, and schematic diagram of the stream network.Figure 24. Simulated discharge from combined Precipitation-Runoff Modeling System and Diffusion...Figure 25. Santiam River Basin and schematic diagram of the stream network.Figure 26. Observed and simulated discharge from combined Precipitation-Runoff Modeling System...Figure 27. McKenzie River Basin, Oregon, and schematic diagram of the stream network.Figure 28. Observed and simulated discharge from combined Precipitation-Runoff Modeling System...Main-Stem NetworksFigure 29. Willamette River and tributary basins from Jasper to Harrisburg, Oregon, and schematic...Figure 30. Observed and simulated discharge from combined Precipitation-Runoff Modeling System...Figure 31. Willamette River and tributary basins from Harrisburg to Albany, Oregon, and schematic...Figure 32. Observed and simulated discharge from combined Precipitation-Runoff Modeling System...Figure 33. Willamette River and tributary basins from Albany to Salem, Oregon, and schematic diagr...Figure 34. Observed and simulated discharge from combined Precipitation-Runoff Modeling System...Figure 35. Willamette River and tributary basins from Salem to Willamette Falls, Oregon, and schem...Figure 36. Observed and simulated discharge from combined Precipitation-Runoff Modeling System...AN EXAMPLE WATER-QUALITY APPLICATIONDescription of the Example BasinUse of the Branched-Lagrangian Transport ModelFigure 37. Branch Lagrangian Transport model simulation of dye transport in the Pudding River, Ore...Figure 38. Branch Lagrangian Transport model simulation of dye transport in the Pudding River, Ore...Figure 39. Branch Lagrangian Transport model simulation of dye transport in the Pudding River, Ore...Table 13. Measured and Precipitation-Runoff Modeling System simulated discharge used to define...Figure 40. Branch Lagrangian Transport model simulation of dye transport in the Pudding River, Ore...Determining Travel Time and Dilution of a Hypothetical SpillFigure 41. Travel time for peak concentrations of a hypothetical spill for various discharges (Q) at th...FUTURE WATER-QUALITY MODELINGLINKING DATA AND MODELSFigure 42. Programs and files used to link the Precipitation-Runoff Modeling System (PRMS), the Diffu...ARC-INFO and Geographic Information System FilesFigure 43. Programs and files used to interface geographic information system (GIS) coverages wi...ANNIE and Water Data Management FilesFigure 44. Program and files used to update the Water Data Management (WDM) data-base file. Precipitation-Runoff Modeling System and Diffusion Analogy Flow Model and FilesFigure 45. Programs and files used in PRMS simulations. Figure 46. Program and files used for Diffusion Analogy Flow (DAFLOW) model simulated operati...Figure 47.