A sediment budget for Town Creek Watershed: preliminary results from streambank erosion processes and rates assessment

Authors: RAMIREZ-AVILA, JOHN - Mississippi State University; Langendoen, Eddy; MCANALLY, WILLIAM - Mississippi State University; ORTEGA-ACHURY, SANDRA - Mississippi State University; MARTIN, JAMES - Mississippi State University

Submitted to: Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE)
Publication Type: Proceedings
Publication Acceptance Date: 4/15/2010
Publication Date: 6/20/2010
Citation: Ramirez-Avila, J.J., Langendoen, E.J., Mcanally, W.H., Ortega-Achury, S.L., Martin, J.L. 2010. A sediment budget for Town Creek Watershed: preliminary results from streambank erosion processes and rates assessment. In: Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE). Paper No. 1009205. 8 pp.

Interpretive Summary: Many streams 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 the affect of bank soil physical properties on erosion rates. 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 have collected a comprehensive data set of bank material properties and erosion rates along selected reaches of Town Creek located in northeastern Mississippi. 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 showed stream bank materials to be highly erodible and to vary significantly along the stream. Erosion rates greatly depended on the presence of riparian vegetation, channel runoff and channel form. 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: Increased streambank erosion results not only in accelerated sediment yield, but also destabilizes streams with associated changes in stream type. This document reports preliminary results from a study which main objective is to evaluate streambank erosion rates and generate empirical correlations to estimate streambank erosion involving physical, geometric, and morphologic variables in the Town Creek watershed in Mississippi. A combination of methods is used for the study including field reconnaissance and detailed data collection, surveying, and channel modeling. Higher rates of increase in sediment load and yield from the northern headwaters were observed from unstable active streambank profiles near agricultural lands and limited or with no presence of riparian vegetation. Streambank failure events at these channels tend to be periodic, most frequently occurred during stormflow events season. Channel morphology changes from incised V-shaped channels to wide U-shaped channels with an increase in riparian vegetation density along the middle 20-km of the principal channel. Streambank erosion pins were installed on two representative places along the middle 20-km of the principal channel. Streambank erosion rate was assessed by measuring the length of the exposed pins after stormflow events on each plot. Assessment showed sediment deposition in most of the pin erosion plots. Jet testing results described streambank soils with high and very high potential to be eroded. Combined preliminary results, watershed characterization and field observation initially point to season and channel morphology as the more important factors affecting streambank erosion and deposition rates on streambanks and streambeds.