Submitted to: Proceedings of the World Environmental and Water Resources Congress Conference
Publication Type: Proceedings
Publication Acceptance Date: 2/15/2010
Publication Date: 5/16/2010
Citation: Ramirez-Avila, J.J., Langendoen, E.J., Mcanally, W.H., Martin, J.L., Ortega-Achury, S.L., Diaz-Ramirez, J.N. 2010. Streambank erosion assessment in southeastern plains ecoregion channels using in situ monitoring and submerged jet testing. Proceedings of the World Environmental and Water Resources Congress Conference. Interpretive Summary: Stream channels in the Town Creek watershed in northeastern Mississippi were channelized in the early 20th century to improve drainage of the adjacent floodplain for cultivation and increase transport of sediments eroded from the adjacent hill slopes. The consequent unnatural channel form has caused an acceleration of erosional processes, especially eroding fine-grained sediments from streambanks. In order to develop practices to reduce the detrimental impact of the increased stream bank loadings on downstream habitat and infrastructure, it is necessary to understand and quantify how streambank erosion depends on bank material properties and the location of the streambank within the watershed. Researchers at the U.S. Department of Agriculture-Agricultural Research Service-National Sedimentation Laboratory and the Department of Civil and Environmental Engineering of Mississippi State University are collecting a comprehensive data set of bank material properties and erosion rates along selected reaches of Town Creek. This data set is used to develop relationships between bank material properties and bank erosion rates for streams in the Southeastern Plain Ecoregion. Preliminary analysis shows erosion rates to vary greatly from upstream to downstream. Erosion dominates in upstream reaches, whereas deposition dominates in downstream reaches. The improved understanding of how bank erosion relates to soil properties, runoff, location within the watershed, and management of the riparian zone can be used by federal, state, and local action agencies to develop more effective practices to reduce stream bank erosion.
Technical Abstract: Channel width adjustment due to stream bank erosion is a common mode of channel form adjustment as streams respond to changes in runoff and sediment supply from the surrounding landscape. This is particularly observed in the highly disturbed watersheds of Northeastern Mississippi. Research is being conducted in the Town Creek watershed, MS to better understand how streambank erosion is affected by the position and characteristics of the eroding streambank in the watershed. Measurements of streambank profile adjustment using erosion pins and topographic surveys, flow velocity, and streambank soil erodibility using a jet test device was conducted at three different locations within the watershed. Soil chemical and physical properties were determined to evaluate effects on streambank soil erodibility. Erosion pins were monitored over a one year period. Topographic surveying has been performed on headwater unstable channels with actively eroding streambanks for six months. Streambank erosion and deposition processes were observed simultaneously at erosion pin locations. Erosion depths ranged from 1 mm to 560 mm, whereas sediment deposition depths varied between 1 and 360 mm. Preliminary survey results indicate erosion varying between 3 and 600 mm due to mass wasting and basal clean-out during and after storm runoff events. Soil streambank critical shear stress and detachment rate coefficient determined by jet testing indicate a wide range of erodibility throughout the test locations.