Stream Flow Response to Climate in Minnesota
ST. ANTHONY FALLS LABORATORY Engineering, Environmental and Geophysical Fluid Dynamics Project Report No. 510 Stream Flow Response to Climate in Minnesota by Filiz Dadaser-Celik and Heinz G. Stefan Prepared for Legislative Citizens Committee on Minnesota Resources St. Paul, Minnesota April 2009 Minneapolis, Minnesota 1 The University of Minnesota is committed to the policy that all persons shall have equal access to its programs, facilities, and employment without regard to race, religion, color, sex, national origin, handicap, age or veteran status. 2 Abstract The variability of stream flows in Minnesota, and the relationship between stream flows and climate are the focus of this report. We analyze historical flow records of Minnesota streams to determine how much frequency and magnitude of flows have been affected by climate and land use changes. Flow duration analysis, high and low flow ranking, and flood frequency analysis were applied to recorded mean daily stream flows, 7-day average low flows, and annual peak flows. Data from 36 gauging stations located in five river basins of Minnesota (Minnesota River, Rainy River, Red River of the North, Lake Superior, and Upper Mississippi River Basins) covering the 1946-2005 period were used. To detect any changes that have occurred over time, data from the 1986-2005 and the 1946-1965 periods of record were analyzed separately. Flow duration curves were prepared for all gauging stations, and low flows (Q90, Q95), medium flows (Q50), and high flows (Q5, Q10) in the two time periods were examined. Multiple stream gauging stations in the same river basin generally showed consistent changes in stream flows, although deviations from a typical river basin pattern were noted at a few gauging stations.
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