Historical Trends in Flood Discharges on the Upper Mississippi River

by H. Vernon Knapp, Illinois State Water Survey, Champaign, United States,

Document Type: Proceeding Paper

Part of: Hydraulic Engineering


Long-term streamgage records in the Upper Mississippi River Basin were analyzed using a Kendall Tau-b analysis to determine trends in flooding and average flows. Over the 130 years of gaging there have been various periods in which the frequency and magnitude of floods have fluctuated. For southern Minnesota, eastern Iowa, and northern Illinois, flows over the last three decades have been higher than any earlier period on record. Trends in flooding and average flow are strongly correlated to coincident increases in average annual precipitation. Though human-induced modifications may have significant impact on flows at the local scale, these influences are not apparent for the large rivers, and may be masked by the climatic variability.

Subject Headings: Floods | Water discharge | Rivers and streams | Fluid flow | Flow measurement | River flow | Water discharge measurement | Flood frequency | Mississippi River | Minnesota | Iowa | Illinois | United States

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