Modeling of fluvial geomorphic processes in river channels impacted by agriculture

Authors: JIA, YAFEI - University Of Mississippi; Langendoen, Eddy

Submitted to: International Conference on Hydroscience and Engineering (ICHE)
Publication Type: Proceedings
Publication Acceptance Date: 7/10/2014
Publication Date: 9/28/2014
Citation: Jia, Y., Langendoen, E.J. 2014. Modeling of fluvial geomorphic processes in river channels impacted by agriculture. International Conference on Hydroscience and Engineering (ICHE). Sep 28-Oct 2, 2014, Hamburg, Germany, pp. 1147-1155.

Interpretive Summary: The US Environmental Protection Agency lists sediment as a leading cause of reduced stream water quality. Sediments eroded from the banks of disturbed streams are a significant contributor of fine-grained sediment. Elevated rates of bank erosion are often caused by scour of the river bed. In-stream structural measures such as drop structures to control channel grade, and spur dikes, large wood and planting of riparian vegetation to control bank erosion have been constructed to reduce channel erosion and its resulting sediment load. Through funding of the US Department of Agriculture scientists at the USDA, ARS National Sedimentation Laboratory and the National Center for Computational Hydroscience and Engineering at the University of Mississippi have developed a suite of computer models ranging from fairly simple to highly complex to assess sediment management strategies in rivers. These models have been successfully tested against a variety of sediment transport problems: scour around bridge piers, channel incision, dam removal, etc. A major conclusion of this long-term effort is that due to the complexity of sediment transport and soil erosion processes, models designed for problems of distinct spatial and time scales will have to be applied in an integrated fashion to be the most cost-effective and to reduce predictive uncertainty.

Technical Abstract: Sediment in water resources has been found to be a major contributor to water quality degradation. Fine-grained sediment emanating from agricultural watersheds is a concern for protecting water resources and environment. A large portion of the sediments may be contributed by channel erosion processes including channel incision, headcut migration, bank erosion, or local scouring. In-stream structural measures such as drop structures to control channel grade, and spur dikes, large wood and planting of riparian vegetation to control bank erosion have been constructed to reduce channel erosion and its resulting sediment load. In the past decades, computer simulation models have been developed to help researchers and engineers understand and resolve these sedimentation problems. Among others, the U.S. Department of Agriculture has developed the one-dimensional CONservational Channel Evolution and Pollutant Transport System (CONCEPTS) for flow and sediment transport routing including bank erosion in river channels at the stream corridor scale. The National Center for Computational Hydroscience and Engineering has developed the multi-dimensional suite of CCHE2D/3D computer models for simulating these processes in more detail at smaller spatial scales, thus emphasizing localized problems. Successful applications of these models have demonstrated their effectiveness and usefulness. Due to the complexity of sediment transport and soil erosion processes, models designed for problems of distinct spatial and time scales will have to be applied in an integrated fashion. An integrated approach to make state-of-the-art numerical models available for research and practical applications will be the most cost-effective.