Title: A computational platform for physically-based bank evolution and long-term meander migration Authors
|Garcia, Marcello -|
|Motta, Davide -|
|Abad, Jorge -|
Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: September 15, 2010
Publication Date: September 21, 2010
Citation: Garcia, M.H., Motta, D., Abad, J.D., Langendoen, E.J. 2010. A computational platform for physically-based bank evolution and long-term meander migration. In: Proceedings of the 1st Congreso Internacional de Hidrologia de Llanuras, Sept. 21-24, 2010, Buenos Aires, Argentina. 8 Pages. Interpretive Summary: No easy-to-use, physically- and process-based tools exist to evaluate the long-term stability of restored meandering streams. Scientists at the USDA-ARS National Sedimentation Laboratory in collaboration with researchers from the University of Illinois have developed a new model that combines the stream bank erosion component of the ARS channel evolution model CONCEPTS with the meander model RVR MEANDER developed by the University of Illinois. This model can be executed within a geographical information system (GIS), which provides the user with an integrated platform to design and evaluate meander planform alignment over aerial imagery. The functioning of the proposed approach is demonstrated through application to a meander restoration project in the Lake Tahoe Basin, CA, and the Mackinaw River, IL. The platform should be beneficial to federal action agencies, such as the US Geological Survey, the US Bureau of Reclamation, the US Corps of Engineers, and the Natural Resources Conservation Service, to design the planform of re-meandering streams and assess the long-term stability and benefits.
Technical Abstract: RVR Meander is a simplified two-dimensional (2D) hydrodynamic and migration model (Abad and Garcia, 2006) while CONCEPTS (CONservational Channel Evolution and Pollutant Transport System) is a one-dimensional (1D) hydrodynamic and morphodynamic model (Langendoen and Alonso, 2008; Langendoen and Simon, 2008; Langendoen et al., 2009). Originally, RVR Meander reported only the use of Ikeda et al. (1981)’s hydrodynamic model, where the bank migration (M) was modeled by using the concept of near bank excess velocity (u_e). In this regard, the bank migration was expressed as M = C * u_e, where C is a bank migration coefficient, calibrated upon historical centerlines. The bed morphology was not modeled according to the sediment mass conservation (Exner equation), but instead it was assumed that the transversal bed slope was directly related to local curvature. On the other hand, CONCEPTS uses an advanced treatment of the bank retreat. However, since CONCEPTS is a 1D model, it does not incorporate corrections for secondary flow and transversal bed slope: therefore its applicability to meander bends might underestimate the shear stress along the stream banks and consequently underpredict the migration rate. This paper shows results of an ongoing effort to merge both models, with the goal of implementing a hydrodynamic and morphodynamic model capable of reproducing the flow field and the river migration for predicting long-term evolution needed in engineering and geological applications.