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Much time and money has been spent over the last 40 years in the U.S. by farmers, soil scientists, hydrologists, geomorphologists, engineers, and ecologists attempting to document how agricultural best management practices, natural vegetation in riparian corridors, and stream rehabilitation or bank stabilization reduces sediment yields and improves ecological conditions at watershed outlets. These issues are especially pertinent in the steep erodible landscape of the Driftless Area in southwest Wisconsin, where many miles of world-class spring-fed trout streams remain on state impaired waters lists from excessive sedimentation and degraded habitat even though this area was the birthplace of the conservation movement...
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We investigate stream response to the La Valle Dam removal and channel reconstruction by estimat- ing channel hydraulic parameter values and changes in sedimentation within the reservoir. The designed channel reconstruction after the dam removal included placement of a riffle structure at the former dam site. Stream surveys undertaken in 1984 by Federal Emergency Management Agency and in 2001 by Doyle et al. were supple- mented with surveys in 2009 and 2011 to study the effects of the instream structure. We created a model in HEC- RAS IV and surface maps in Surfer© using the 1984, 2009, and 2011 surveys. The HEC-RAS IV model for 2009 channel conditions indicates that the riffle structure decreases upstream channel...
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Agricultural landscapes are more sensitive to climatic variability than natural landscapes because tillage and grazing typically reduce water infiltration and increase rates and magnitudes of surface runoff. This paper evaluates how agricultural land use influenced the relative responsiveness of floods, erosion, and sedimentation to extreme and nonextreme hydrologic activity occurring in watersheds of the Upper Mississippi Valley. Temporally overlapping stratigraphic and historical instrumental records from southwestern Wisconsin and northwestern Illinois show how agricultural modification of a natural prairie and forest land cover affected the behavior of floods and sedimentation during the last two centuries....
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Understanding the time scales and pathways for response and recovery of rivers and floodplains to episodic changes in erosion and sedimentation has been a long standing issue in fluvial geomorphology. Floodplains are an important component of watershed systems because they affect downstream storage and delivery of overbank flood waters, and they also serve as sources and temporary sinks for sediments and toxic substances delivered by river systems. Here, 14C and 137Cs isotopic dating methods are used along with ages of culturally related phenomena associated with mining and agriculture to determine rates of sedimentation and morphologic change for a reach of the upper Mississippi River and adjacent tributaries in...
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