Simulated Water-Management Alternatives Using the Modular Modeling System for the Methow River Basin, Washington
GEOLOGICAL SURVEY RESTON VA WATER RESOURCES DIV
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A precipitation-runoff model for the Methow River Basin was used to simulate six alternatives 1 baseline of current flow, 2 line irrigation canals to limit seepage losses, 3 increase surface-water diversions through unlined canals for aquifer recharge, 4 convert from surface-water to groundwater resources to supply water for irrigation, and 5 reduce tree density in forested headwater catchments, and 6 natural flow. Daily streamflow from October 1, 1959, to September 30, 2001 water years 1960-2001 was simulated. Lining irrigation canals alternative 2 increased flows in the Chewuch, Twisp, and the Methow upstream and at Twisp Rivers during September because of lower diversion rates, but not in the Methow River near Pateros. Increasing diversions for aquifer recharge alternative 3 increased streamflow from September into January, but reduced streamflow earlier in the summer. Conversion of surface-water diversions to ground-water wells alternative 4 resulted in the largest increase in September streamflow of any alternative, but also marginally lower January flows at most -8 percent in the 90-percent exceedance value. Forest-cover reduction alternative 5 produced large increases in streamflow during high-flow periods in May and June and earlier onset of high flows and small increases in January streamflows. September streamflows were largely unaffected by alternative 5. Natural streamflow alternative 6 was higher in September and lower in January than the baseline alternative.
- Hydrology, Limnology and Potamology