SEDIMENT DELIVERY CHANGES RELATED TO PERSISTING SEDIMENT YIELDS FROM THE BUFFALO RIVER, WEST-CENTRAL WISCONSIN

Authors: FAULKNER, DOUGLAS - UNIV MISSOURI-KANSAS CIRY; McIntyre, Sherwood

Submitted to: Water Resources Bulletin
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Despite application of soil conservation practices and changes in land use that have reduced erosion in agricultural watersheds over the past sixty years, sediment yields from some watersheds have remained high. A case in point is the Buffalo rive watershed in southwestern Wisconsin. The watershed was investigated in 1993 using aerial photographs, historical land use records, and Cs-137 techniques to determine the cause of the continued high sediment yield. Results of the study indicated that through time stream channels that drain the watershed have enlarged, decreasing alluvial sediment storage and increasing sediment conveyance. Study findings are significant because they indicate that erosion control on agricultural land does not insure reductions in sediment yields. Findings further indicate that entire watershed systems must be considered to determine the cause of continued sediment yield and to plan management strategies for sediment.

Technical Abstract: The Buffalo River is a tributary to the Mississippi River in west-central Wisconsin that drains a watershed dominated by agricultural land uses. Since 1935, backwater from Lock and Dam 4 on the Mississippi River has inundated the mouth of the Buffalo s valley. Resurveys of a transect first surveyed across the lake in 1935 and cesium-137 dating of backwater sediments reveal that sedimentation rates at the Buffalo s mouth have remained unchanged since the mid 1940s. This indicates that sediment yields from the watershed have persisted at relatively high levels over a period of several decades despite pronounced trends toward less cultivated land and more forested land, and despite major efforts to control soil erosion from agricultural land. The maintenance of sediment yields is probably due to increased channel conveyance capacities resulting from incision along some tributary streams since the early 1950s. This episode of incision extended the network of historical incised tributary channels, enhancing the efficient delivery of sediment from upland sources to downstream sites.