Precipitation-Runoff and Streamflow-Routing Models for the Willamette River Basin, Oregon U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 95–4284 Prepared in cooperation with OREGON DEPARTMENT OF ENVIRONMENTAL QUALITY Cover photograph. Cottonwood seeds float on the Willamette River looking upstream between Harrisburg and Eugene (at river mile 169), June 24, 1993. (Photograph by Dennis A. Wentz, U.S. Geological Survey.) Precipitation-Runoff and Streamflow-Routing Models for the Willamette River Basin, Oregon By ANTONIUS LAENEN and JOHN C. RISLEY U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 95–4284 Prepared in cooperation with OREGON DEPARTMENT OF ENVIRONMENTAL QUALITY Portland, Oregon 1997 I U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Gordon P. Eaton, Director Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. _________________________________________________________________________________________________ For additional information Copies of this report can write to: be purchased from: District Chief U.S. Geological Survey U.S. Geological Survey, WRD Branch of Information Services 10615 S.E. Cherry Blossom Drive Box 25286 Portland, Oregon 97216 Federal Center E-mail: [email protected] Denver, Colorado 80225 II CONTENTS Abstract ...................................................................................................................................................................................... 1 Introduction................................................................................................................................................................................ 2 Background ...................................................................................................................................................................... 2 Purpose and Scope ........................................................................................................................................................... 3 Approach.......................................................................................................................................................................... 3 Study Area Description.................................................................................................................................................... 5 Acknowledgments............................................................................................................................................................ 7 Precipitation-Runoff Models...................................................................................................................................................... 7 Description of Precipitation-Runoff Modeling System ................................................................................................... 7 Time-Series Data.............................................................................................................................................................. 9 Precipitation ........................................................................................................................................................... 9 Air Temperature ..................................................................................................................................................... 9 Discharge................................................................................................................................................................ 9 Delineation of Basin Physical Characteristics ................................................................................................................. 9 Model Parameterization ................................................................................................................................................. 18 Hydrologic Response Unit-Related Parameters................................................................................................... 18 Basinwide Parameters .......................................................................................................................................... 22 Model Calibration and Verification................................................................................................................................ 22 Water-Budget Adjustments .................................................................................................................................. 25 Sensitivity Analysis.............................................................................................................................................. 25 Parameter Optimization ....................................................................................................................................... 25 Simulation Results ............................................................................................................................................... 27 Estimation of Parameters in Ungaged Basins ...................................................................................................... 30 Streamflow-Routing Models .................................................................................................................................................... 30 Description of Diffusion Analogy Flow Model ............................................................................................................. 30 Channel Reach Delineation............................................................................................................................................ 31 Model Parameterization ................................................................................................................................................. 31 Area Parameter..................................................................................................................................................... 32 Width Parameter................................................................................................................................................... 32 Diffusion Coefficients .......................................................................................................................................... 33 Special Studies to Document Low Flow........................................................................................................................ 33 Time-of-Travel Studies ........................................................................................................................................ 33 Gain-Loss Investigations...................................................................................................................................... 34 Network-Routing Applications ................................................................................................................................................ 35 Tributary Networks ........................................................................................................................................................ 37 Johnson Creek ...................................................................................................................................................... 37 Clackamas River .................................................................................................................................................. 38 Tualatin River....................................................................................................................................................... 41 Molalla River........................................................................................................................................................ 43 Yamhill River ....................................................................................................................................................... 45 Santiam River....................................................................................................................................................... 47 McKenzie River ................................................................................................................................................... 49 Main-Stem Networks ..................................................................................................................................................... 51 Willamette River from Jasper to Harrisburg ........................................................................................................ 51 Willamette River from Harrisburg to Albany....................................................................................................... 53 Willamette River from Albany to Salem.............................................................................................................. 54 Willamette River from Salem to Willamette Falls ............................................................................................... 55 An Example Water-Quality Application.................................................................................................................................. 58 Description of the Example Basin ................................................................................................................................. 58 Use of the