Application of a Depth-Averaged 2-D Model in River Restoration

A depth-averaged 2-D model has been developed for analyzing the impact of river restoration projects on flow, sediment transport, water quality, and ecology in aquatic systems. The hydrodynamic model solves the depth-averaged 2-D shallow water equations using the finite volume method on a non-staggered, curvilinear grid. It uses SIMPLE(C) procedures with Rhie and Chow's momentum interpolation technique to handle the pressure-velocity coupling. The model simulates the nonequilibrium transport of nonuniform total-load sediment. The non-cohesive sediment transport capacity is determined by one of four formulas that all account for the hiding and exposure effects among different size classes in bed material. The model is enhanced to consider the effect of helical flow motions on main flow and sediment transport in curved channels, local scour around bridge piers and spur-dikes, effect of vegetation on fluvial processes, and cohesive sediment transport. The model also simulates heat transfer, pollutant transport and water quality in aquatic systems. The habitat suitability for various fish species is analyzed by using the simulated results of flow depth, velocity, temperature, dissolved oxygen, etc. The model has been well tested using experimental and filed data, and applied to help solve problems in river restoration projects.