Submitted to: Journal of Hydraulic Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/20/2007
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. Scientists of the U.S. Department of Agriculture-Agricultural Research Service 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 U.S. Department of Agriculture, Agricultural Research Service, 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 tested on the Goodwin Creek, Mississippi for the period between March 1996 and February 2001. It accurately predicts the retreat of the outside bank of a river bend of the creek. CONCEPTS is therefore a tool that can be used by the U.S. Army Corps of Engineers and the U.S. Department of Agriculture-Natural Resources Conservation Service 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 fine-grained 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 on Goodwin Creek, Mississippi between March 1996 and March 2001 where it accurately predicts the rate of retreat of the outside bank of the bendway. The observed change in average channel width within the central section of the bendway is 2.96 m over the simulation period, whereas CONCEPTS predicted a retreat of 3.18 m. The observed top-bank retreat within the central section of the bendway is 3.54 m over the simulation period, whereas CONCEPTS predicted a retreat of 3.01 m.