Submitted to: Journal of Hydraulic Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2007
Publication Date: 7/1/2008
Citation: Langendoen, E.J., Simon, A. 2008. Modeling the evolution of incised streams. II: Streambank erosion. Journal of Hydraulic Engineering. 134(7):905-915. Interpretive Summary: Many of the 3.5 million miles of rivers in the United States are in a degraded condition. Rivers have been channelized and their floodplains have been overtaken by development. Channels have responded by adjusting their shape. ARS scientists have shown that in the midsouth and midwestern United States up to 80% of the sediments eroded from the stream channel may originate from the banks of the channel. The USDA-ARS National Sedimentation Laboratory (NSL) conducts field studies to characterize physical processes responsible for streambank erosion. Results from these studies are used to enhance the NSL's long-term channel evolution computer model CONCEPTS. The model has been field validated on the Goodwin Creek, Mississippi. The CONCEPTS model accurately predicts the retreat of the outside bank of a river bend of the creek. CONCEPTS is a state-of-the-art tool used successfully by the USDA Natural Resources Conservation Service, the U.S. Army Corps of Engineers-Vicksburg District, the U.S. Geological Survey-Omaha, NE, and Kalamazoo, MI, Districts, to assess the impact of instream hydraulic structures to control channel erosion.
Technical Abstract: Incision and ensuing widening of alluvial stream channels is widespread in the midsouth and midwestern United States. The U.S. Department of Agriculture, Agricultural Research Service, National Sedimentation Laboratory (NSL) conducts field studies to characterize the resistance of cohesive materials to hydraulic erosion, the impact of pore-water pressures on failure dimensions and shearing resistance, and the role of riparian vegetation on matric suction, streambank permeability, and shearing resistance. Results from these studies are used to enhance the NSL's long-term channel evolution model CONCEPTS. This paper discusses the conceptualization of the above physical processes, and demonstrates the ability of CONCEPTS to simulate streambank failure processes. The model has been tested against observed streambank erosion of a bendway in the Goodwin Creek, Mississippi, between March 1996 and February 2001. It accurately predicts the rate of retreat of the outside bank of the bendway. The observed average top-bank retreat of the outside bank within the central section of the bendway is 2.94 m, whereas CONCEPTS predicted an average retreat of 3.10 m.