Determining Surface Water Availability in Oregon
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Determining Surface Water Availability in Oregon Open File Report SW 02-002 State of Oregon Water Resources Department Determining Surface Water Availability in Oregon By Richard M. Cooper, PE State of Oregon Water Resources Department Open File Report SW 02-002 Salem, Oregon June 2002 Cover photo: Watermaster Awbrey Perry measuring Tumalo Creek 200 feet above the station house for gaging station 14073000 on February 9, 1948. Note the ice floating in the creek. Contents Table of Contents........................................................................................................................................... i List of Figures................................................................................................................................................iii List of Tables................................................................................................................................................. v Acknowledgements .....................................................................................................................................vii Abstract ........................................................................................................................................................ 1 Introduction .................................................................................................................................................. 2 The Water Availability Calculation.......................................................................................................... 2 Natural Stream Flow ........................................................................................................................ 3 Storage............................................................................................................................................. 3 Consumptive Use ............................................................................................................................ 3 In-Stream Demands......................................................................................................................... 4 Where Water Availability is Calculated................................................................................................... 4 Predicting Future Stream Flow............................................................................................................... 5 Calculating Water Availability........................................................................................................................ 9 Measured Watershed Stream Flow Analysis ....................................................................................... 11 Calculation of Exceedance Flows from a Continuous Record....................................................... 11 Selecting a Base Period................................................................................................................. 12 Correcting to a Base Period........................................................................................................... 14 Calculation of Exceedance Flows from Miscellaneous Measurements......................................... 17 Selecting an Index Station ............................................................................................................. 21 By Comparison of Watershed Characteristics......................................................................... 24 By Comparison of Flow Duration Curves ................................................................................ 24 Correcting to Natural Stream Flow................................................................................................. 24 Unmeasured Watershed Stream Flow Analysis .................................................................................. 28 Estimating Stream Flow from a Regional Regression Analysis – an Example Calculation........... 29 Defining the Mathematical Relationship Between Stream Flow and Watershed Characteristics.. 30 Transforming the Data ................................................................................................................... 30 Estimating Watershed Characteristics........................................................................................... 32 Goodness of Fit.............................................................................................................................. 33 Stream Flow Correction ................................................................................................................. 35 Storage and Consumptive Use Demands ............................................................................................ 38 Storage........................................................................................................................................... 38 Consumptive Use........................................................................................................................... 40 Estimating Irrigation Consumptive Use ................................................................................... 42 Methods that Over-Estimate Irrigation Consumptive Use ....................................................... 46 Estimating Municipal Consumptive Use .................................................................................. 53 i Estimating Other Consumptive Uses ...................................................................................... 54 The Water Availability Reporting System (WARS) .................................................................................... 55 Things to Keep in Mind about Water Availability .................................................................................. 55 Uncertainty of Water Availability Estimates .......................................................................................... 56 References.................................................................................................................................................. 57 Appendix A.................................................................................................................................................. 59 Appendix B.................................................................................................................................................. 67 Appendix C.................................................................................................................................................. 87 Appendix D.................................................................................................................................................. 91 Appendix E.................................................................................................................................................. 97 Appendix F ................................................................................................................................................ 105 ii Figures Figure1. Nested Water Availability Basins – An Example: North Fork Siuslaw River. ........................... 5 Figure2. Water Availability Basins and OWRD Administrative Basins .................................................... 6 Figure 3. Mean Annual Stream Flow for Four Long-Term Gages in Oregon: a) 14048000, John Day River at McDonald Ferry, OR; b) 14174000, Willamette River at Albany, OR; c) 14310000, Umpqua River at Elkton, OR; and d) Rogue River at Raygold near Central Point, OR ........... 8 Figure 4. The Water Availability Methodology – an Overview................................................................ 10 Figure 5. The Water Availability Methodology – Measured Watershed Stream Flow Analysis.............. 11 Figure 6. Number of Complete Years of Record for All Gages in Oregon ............................................. 13 Figure 7. January Short Record Flow Duration Curve for the Wilson River near Tillamook, OR – Gage 14301500 ...................................................................................................................... 18 Figure 8. January Concurrent and Base Period Flow Duration Curves for the Nehalem River near Foss, OR – Gage 14301000 ................................................................................................... 18 Figure 9. Relationship Between January Exceedance Stream Flows for the Nehalem River near Foss (Gage 14301000) and the Wilson River near Tillamook, OR (Gage 143015000) for the Concurrent Period 1973-1982.......................................................................................... 19 Figure 10. Comparison of January Flow Duration Curves for the Wilson River near Tillamook, OR – Gage 14301500....................................................................................................................... 19 Figure 11. Relationship Between Stream Flow at Sun Creek (Gage 21420310 – Miscellaneous Measurements) and Annie Creek ( Gage 61420301– Mean Daily Flows) ............................. 23 Figure 12. January 50-Percent Exceedance Stream Flow vs. Watershed Area for Gaged Streams West of the Cascade Crest Using Log-Transformed Data...................................................... 28 Figure 13. January 50-Percent Exceedance Stream Flow vs. Watershed Area for Gaged Streams West of the Cascade Crest Using Non-Log-Transformed Variables ...................................... 31 Figure 14. Percent Elevation above 3000 Feet vs. 50-Percent Exceedance Stream Flow – for Gages East of Cascade Crest................................................................................................