Abstract

The need to know how river morphology changes due to sedimentation is increasingly important as we attempt to predict future events. Engineers use numeric models to predict effects of changed morphology on river systems. The numerical model Two-dimensional Unsteady Flow (TUFLOW) has recently added, and is continually improving, its capability to model sediment transport in rivers and coastal systems. This paper evaluates the new tools for modeling sediment transport presently contained within TUFLOW and compares these tools with analytical and laboratory case studies. Currently TUFLOW simulates combined bed and suspended load transport of noncohesive sediments under the effect of currents using the Van Rijn method. New TUFLOW capabilities which have not been extensively tested before include recognized sediment transport relationships such as those of Meyer-Peter and Mueller, Bagnold, and Ackers & White. It is important to note that the software evaluated herein is a snapshot of a continuing software development process. The aim of the TUFLOW developers is to address any shortcomings outlined in this paper where feasible. Eleven different test cases are modeled in the Surface-water Modeling System (SMS) software. The test cases are designed to examine how well TUFLOW simulates sediment transport modeling with channels of varying degrees of slope and contractions. Eight of the test cases are taken from Analysis of the Sediment Transport Capabilities of FESWMS. Three cases simulate a simple flume with varying midsection slopes. Four cases use a simple flume with no slope and different contractions: a short abrupt contraction, a long abrupt contraction, a long gradual contraction, and a wide contraction. Two of the test cases are from laboratory flume experiments that were performed at St. Anthony Falls Laboratory. The last test case consists of a river entering a reservoir. The results show that TUFLOW is presently capable of representing sediment transport and morphology reasonably on moderate and shallow slopes and channels with contractions. However, more work is required to improve TUFLOW's morphological capabilities on steep slopes when hydraulic jumps are present. The results show TUFLOW can handle long term simulations. The results show that TUFLOW is not capable at this time of recreating the lab flumes and more features need to be added to accurately portray the flumes. TUFLOW did show perturbations, common for semi-coupled models, in the results for certain test cases. Filtering, a common way of removing perturbations was implemented and gave varying results. The developers are in the process of developing a more advanced scheme for filtering.

Degree

College and Department

Ira A. Fulton College of Engineering and Technology; Civil and Environmental Engineering

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