| Popis: |
Mean and peak flows, channel width, and rates of meander migration are examined for two sandy meandering reaches of the Milk River in south Alberta and north Montana. One reach, upstream of the international boundary near Onefour, Alberta, is affected by the St. Mary diversion. The other reach near Havre, Montana is below the Fresno Dam and reservoir. Comparisons are possible because of the ample and long-term availability of maps, air photos, and hydrometric records preceding and succeeding the two altered flows for both reaches. Understanding the natural river regime and effects of diversion and dam storage are critical for predicting channel responses to a proposed additional dam on the Milk River. Results indicate that increased discharge due to a diversion has increased channel width 5.5 m and increased the rate of meander migration by 0.85 m/year. Downriver, reservoir storage has decreased channel width 16.8 m and the rate of meander migration by 1.3 m/year and caused channel bed degradation up to 1.5 m near the dam. |
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