Streambank Erosion Assessment in Southeastern Plains Ecoregion Channels Using In Situ Monitoring and Submerged Jet Testing

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 (τ_c) and detachment rate coefficient (k_d) determined by jet testing indicate a wide range of erodibility throughout the test locations.