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Title: NUMERICAL SIMULATION OF TWO-DIMENSIONAL HEADCUT MIGRATION

Author
item WU, WEIMING - CCHE, OXFORD, MS
item WANG, SAM - CCHE, OXFORD, MS
item JIA, YAFEI - CCHE, OXFORD, MS
item Robinson, Kerry

Submitted to: American Society of Civil Engineers Water Resources Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/8/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Predicting the evolution of a stream channel can be a complex process. Channel meandering, bank stability, headcut movement and sediment transport rates are just a few of the processes that must be accurately modeled. This research was conducted to predict the rate of headcut movement and the resulting channel responses. The model predicted the forces on the boundary yof a headcut and determined the rate of headcut movement, scour hole development, and sediment transport. The model does a reasonable job of representing measured data. The results should be of interest to water resource managers, engineers, and other researchers interested in channel evolution. This model enhances our understanding of a complex process.

Technical Abstract: Headcut migration is determined by a time-averaged headcut migration model that considers the frictional erosion on the vertical surface of a headcut due to the hydraulic shear of the flow and geotechnical failure of a headcut due to the scour at the toe of the headcut. The local scour process below the headcut is simulated with the sediment transport model of FAST3D.river code, in which van Rijn's formula for the bed-load transport rate and near-bed suspended-load concentration are implemented after modified by considering the influence of the dynamic pressure gradient, downward flow, bed slope and turbulent intensity on sediment movements. The flow model of FAST3D.river code is verified by using twenty out of 107 sets of experimental data of Robinson (1992). The magnitude and distribution of the shear stresses on the vertical surface and basin floor as well as the main flow features of jet impingement are reasonably predicted. The numerical model is applied to calculate the headcut migration experimentally studied by Bennett et al. (1997). The morphology of scour hole and the headcut migration rate calculated by the numerical model agree well with those measured in the experiment.