Predicting streambank erosion rates and instabilities in incised streams using the model CONCEPTS

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

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/31/2018
Publication Date: 9/24/2018
Citation: Ramirez-Avila, J.J., Langendoen, E.J., Mcanally, W., Martin, J.L., Ortega-Achury, S.L., Bingner, R.L. 2018. Predicting streambank erosion rates and instabilities in incised streams using the model CONCEPTS. Proceedings of the XIII Brazilian Meeting of Sediment Engineering, Victoria/ES, Brazil, September 24-28, 2018,(http://www.abrh.org.br/xiiienes_en/index.php?ID=211). 8 PP.

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 stream banks causing navigation problems downstream on the Tennessee-Tombigbee Waterway. Because the prediction of erosion is an important component in the development of land management strategies, researchers at USDA, ARS, Oxford, MS, and the Department of Civil and Environmental Engineering of Mississippi State University have evaluated the ability of the USDA Conservational Channel Evolution and Pollutant Transport System (CONCEPTS) computer model to predict stream bank erosion along the Town Creek Watershed. Model predictions over a 13 month period were compared with cross section surveys at 8 transects along an incised reach (Yonaba Creek). Results showed that CONCEPTS accurately predicted top bank retreat and timings and magnitudes of stream bank failures. Results from field monitoring and computational modeling offered important insights into the relative effects of land and stream bank erosion on the stream water quality and sediment budget for Town Creek Watershed. Further, reduction of suspended sediment loads should focus on the stabilization of reaches and agricultural lands near stream banks along the headwaters of the watershed.

Technical Abstract: The ability of the CONCEPTS model to predict streambank erosion in disturbed streams was tested through its application to a 270-m reach along the Yonaba Creek in Mississippi, USA. Model predictions were compared with cross section resurveys of 8 transects along the modeling reach for a 13-month period (February 2009 to March 2010). Streambank gravitational failure was the dominant mechanism inducing streambank erosion for the studied reach. Results showed that CONCEPTS was accurate in predicting top width retreat and streambank failures in time and magnitude. CONCEPTS simulation yielded streambank degradation predictions comparable to those observed during the studied period. A maximum annual widening rate of about 3.62-m and annual streambank sediment load of about 2,000-Mg of streambank material were assessed by both methods; field measurements and CONCEPTS modeling. However, CONCEPTS did not account for sediment deposition that occurred on the streambank, a condition that slightly reduced the observed net amount of sediment yield contributed by in-stream processes. CONCEPTS is a tool capable to support decision making regarding reduction of sediment loads, especially for assessment of in-stream management processes and evaluation of stabilization of eroding streambanks and/or stream restoration designs.