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ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Watershed Physical Processes Research » Research » Publications at this Location » Publication #224259
Title: Modeling Flow and Vegetation Effects in a Curved Channel

Author
item JIA, YAFEI - NCCHE, U. OF MISSISSIPPI
item Alonso, Carlos
item Simon, Andrew
item Wells, Robert - Rob
item WANG, SAM - NCCHE, U. OF MISSISSIPPI

Submitted to: Environmental and Water Resources Institute World Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/20/2008
Publication Date: 5/12/2008
Citation: Jia, Y., Alonso, C.V., Simon, A., Wells, R.R., Wang, S. 2008. Modeling Flow and Vegetation Effects in a Curved Channel. Environmental and Water Resources Institute World Congress Proceedings. pp 1-13 (doi 10.1061/40976(316)472).

Interpretive Summary: Streamflow in a meandering channel covered to varying degrees by vegetation is very complex. This is particularly important when trying to predict whether streamflow has sufficient force to erode the bed and the base of the bank. To calculate the forces acting of the stream bed and channel banks requires a sophisticated numerical model that can simulate flow in three dimensions. A numerical model developed by the National Center for Computational Hydroscience Engineering at the University of Mississippi was used to predict the stress imposed by flowing water along a bendway of Goodwin Creek, Mississippi. Using data collected at the bendway, simulation results show lateral variations in stress typical of a meander bend but are largely effected by vegetation growing at the margins of the channel. Maximum stresses were simulated just downstream of the bend apex. The vegetation serves to slow flow velocities and reduce the stress imposed on the channel boundary, thereby limiting the potential for erosion.

Technical Abstract: Channel bank erosion devastates land of agriculture, contributes largely to the sediment yield from watersheds, and deteriorates the downstream channel morphology and water quality. An important part of the bank erosion is due to bank failure known to be related to many factors including properties of bank materials, porous water, roots of vegetation in the bank, and the hydrological process in the channel. However, bank erosion is also affected by the hydrodynamics of the channel flow, the shear stress due to the flow would erode the bed (bank toe) and the bank surfaces resulting in not only sediment yield directly but also more potential mass failures. In this study, the numerical models developed at the NCCHE, CCHE3D/2D, were applied to simulate the flow in a natural channel, Goodwin Creek, Northern Mississippi, with a complex topography. Vegetation effects were modeled, since woody vegetations occupy a large portion of the channel strongly affecting the flow distribution. In addition, the main flow, helical secondary current and the associated shear stress distribution in the main channel are affected by the flow from a side channel. This study is intended to resolve the 3D flow field and its associated shear stress distribution in this curved channel. The information of flow pattern and shear stress from the numerical analysis will be applied to bank erosion and channel change studies. Flow data, channel topography, and in-stream vegetation condition were provided by the National Sedimentation Laboratory.