Estimated Baseflow Characteristics of Selected Washington Rivers and Streams
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Estimated Baseflow Characteristics of Selected Washington Rivers and Streams Water Supply Bulletin No. 60 October 1999 Publication No. 99-327 printed on recycled paper The Department of Ecology is an equal opportunity agency and does not discriminate on the basis of race, creed, color, disability, age, religion, national origin, sex, marital status, disabled veteran's status, Vietnam Era veteran's status or sexual orientation. If you have special accommodation needs or require this document in alternative format, please contact the Environmental Assessment Program, Joan LeTourneau at (360) 407-6764 (voice). Ecology's telecommunications device for the deaf (TDD) number at Ecology Headquarters is (360) 407-6006. For additional copies of this publication, please contact: Department of Ecology Publications Distributions Office P. O. Box 47600 Olympia, Washington 98504-7600 (360) 407-7472 Refer to Publication Number 99-327 This report is also available on Ecology’s home page on the world wide web, at http://www.wa.gov/ecology/biblio/99327.html The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the Department of Ecology or the state of Washington. Estimated Baseflow Characteristics of Selected Washington Rivers and Streams Water Supply Bulletin No. 60 by Kirk A. Sinclair and Charles F. Pitz Washington State Department of Ecology Environmental Assessment Program Olympia, Washington 98504-7710 October 1999 Publication No. 99-327 printed on recycled paper This page is purposely left blank for duplex printing Table of Contents Page List of Figures .....................................................................................................................ii List of Plates.......................................................................................................................iii Acknowledgements ............................................................................................................iv Abstract ............................................................................................................................ v Glossary ..........................................................................................................................vii Introduction ......................................................................................................................... 1 Purpose and scope ......................................................................................................... 2 Previous investigations.................................................................................................. 2 Theoretical background................................................................................................. 3 Study Methods..................................................................................................................... 5 Compilation of streamflow data.................................................................................... 5 Statistical data analysis.................................................................................................. 6 Compilation and preparation of digital data.................................................................. 7 Results .......................................................................................................................... 11 Monthly statistics ........................................................................................................11 Annual statistics .......................................................................................................... 11 Data Limitations................................................................................................................12 Period of data record ................................................................................................... 12 Length of data record .................................................................................................. 12 Streamflow regulation................................................................................................. 12 Drainage area............................................................................................................... 14 Snow/glacial melt........................................................................................................ 15 Alternative baseflow analysis techniques ................................................................... 17 Summary and Conclusions................................................................................................ 19 Recommendations and Suggestions for Additional Study............................................... 21 References ......................................................................................................................... 23 Appendices A. Characteristics of Modeled Gaging Stations B. Monthly Summary Statistics for Baseflow and Streamflow C. Annual Summary Statistics for Baseflow and Streamflow D. Digital Data and GIS Project Files (in the report folder - not included in the pdf version) Page i List of Figures Page Figure 1: Base Flow Separation Using the Local Minimum Method, S.F. Skykomish River Near Index, WA (USGS 12133000) ........................................................ 4 Figure 2: Graphical Depiction of Baseflow Statistics, Black River at Littlerock, WA. (USGS 12029000) ............................................................................................. 7 Figure 3: Comparison of Annual Mean Streamflow, Estimated Annual Mean Baseflow, and Annual 7-Day Low Flow, Naselle River Near Naselle, WA. (USGS 12010000) ............................................................................................. 9 Figure 4: Comparison of Estimated Monthly Mean Baseflow, Mean Surface Runoff, and Mean Streamflow, Naselle River Near Naselle, WA. (USGS 12010000) 10 Figure 5: August Baseflow and Total Streamflow, Wynoochee River Above Black Creek Near Montesano, WA. (USGS 12037400) ................................. 13 Figure 6: Comparison of Annual Mean Streamflow, Estimated Annual Mean Baseflow, and Annual 7-day Low Flow, Wynoochee River Above Black Creek Near Montesano, WA. (USGS 12037400) ................................. 15 Figure 7: Comparison of Estimated Monthly Mean Baseflow, Mean Surface Runoff, and Mean Streamflow, Chamokane Creek Below Falls Near Long Lake, WA (USGS 12433200) ............................................................................................ 16 . Page ii List of Plates (Plates are located in the report folder - or at the back of this pdf) Plate 1: Distribution of Modeled Gaging Stations Plate 2: Gaging Station Features 2A: Years of Data Used to Estimate Baseflow 2B: Degree of Stream Regulation 2C: Drainage Area of Modeled Stations Plate 3: Estimated Baseflow Contributions to Total Streamflow by Season 3A: Mean Baseflow as a Percentage of Total Streamflow – February 3B: Mean Baseflow as a Percentage of Total Streamflow – May 3C: Mean Baseflow as a Percentage of Total Streamflow – August 3D: Mean Baseflow as a Percentage of Total Streamflow – November Plate 4: Watershed Hydrology 4A: Median of Annual Means – Total Streamflow (ft3/sec) 4B: Median of Annual Means – 7-day Low Flow (ft3/sec) 4C: Median of Annual Means – Estimated Baseflow (ft3/sec) Plate 5: Estimated Baseflow Characteristics 5A: Median of Annual Means – Estimated Baseflow as a Percentage of Total Streamflow 5B: Median of Annual Means – Estimated Baseflow (in) – Streams with Little or No Reported Regulation 5C: Median of Annual Means – Estimated Unit-area Baseflow (ft3/sec/mi2) – Streams with Little or No Reported Regulation Page iii Acknowledgements This study would not have been possible without the support and contributions of others at the Washington State Department of Ecology (Ecology) and at the U.S. Geological Survey (USGS). We want to express our appreciation to the following: USGS ◊ Michele Crouse for expediting public distribution of HYSEP and for her insights regarding use of the HYSEP program. ◊ The many hydrologists, technicians, and computer specialists who, over the years, built and maintained the stream gages and computer databases this study drew upon. Ecology ◊ Will Kendra, Larry Goldstein, and Bill Backous who supported and funded this study. ◊ John Covert, John Roland, Linton Wildrick, Art Larson, Todd Kirk, Kirk Cook and Doug McChesney who reviewed and commented on drafts of this report. ◊ Joan LeTourneau who edited and formatted the final report. ◊ Steve Barrett for posting this report on the Internet. Page iv Abstract Automated hydrograph separation techniques were used to evaluate the groundwater contribution to total streamflow (baseflow) at active and inactive stream gaging stations throughout Washington State. Discharge records for 582 gaging stations, with at least three complete water years of daily mean streamflow data, were downloaded from the U.S. Geological Survey (USGS) National Water Information System. Station characteristics were compiled for each gage, including period of streamflow record, type and degree of regulation affecting the gage, watershed drainage area, USGS station number, station name, and gage location. Summary statistics were calculated for annual mean streamflow and annual 7-day low flow for all 582 stations. Monthly, and in some cases annual, statistics for baseflow were then estimated using a USGS hydrograph separation software program called HYSEP (Sloto and Crouse,