Title

Sediment Loads in the Minnesota River Increase the Rate of Channel Migration

Authors

Tim Beach

Document Type

Presentation

Journal/Book Title/Conference

USU Student Showcase

Publication Date

4-2014

Faculty Mentor

Patrick Belmont

Abstract

The presence of sediment in rivers is normal, but excess sediment loads can lead to impairment of water quality and loss of aquatic biota. The Minnesota River, which flows across the southern end of Minnesota, has an unusually high suspended sediment load. The Blue Earth River and its major tributary, the Le Sueur River, disproportionally contribute suspended sediments to the Minnesota. The Le Sueur connects near the mouth of the Minnesota River and adds at least 30 percent of the total Minnesota River sediment load. Excess sediment in a channel influences the rate of lateral migration. The results of this study show how the Minnesota River has migrated as a response to the increase in sediment load. Methods consisted of aerial photo analysis from a portion of the river upstream from the city of Mankato, Minnesota (where the Le Sueur meets the Minnesota River), directly downstream from Mankato, and even further downstream from Mankato. Photos from the years 1991, 2001, 2007 and 2012 were analyzed in ESRI's ArcGIS, and the distances the channel migrated between each year were charted. The portion of the Minnesota River directly downstream from Mankato experienced one of the greatest changes in location, from which we can infer that additional sediment loads from the Le Sueur River directly influence the rate of channel migration.

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