Watershed Runoff and Erosion Modeling with a Hybrid Mesh Model

Abstract

Distributed watershed modeling has gained popularity in recent years. Prevalent models in the United States include CASC2D and WEPP, among others. Although the existing models have been successful for some applications, a number of limitations exist. This paper presents a new watershed runoff and erosion model, SRH-W, with the aim to improve the numerical methods used by the existing models. The new model builds upon process features of the existing models such as CASC2D. However, a new representation of the watershed geometry with the zonal hybrid mesh is proposed, and a new solution technique with the conservative finite-volume formulation is implemented. The modeling concept and the mathematical and numerical formulations are first described. An illustrative case is then simulated to show some new features of the model. A number of verification and validation cases are also presented to demonstrate the model performance, accuracy, and efficiency. The new model is flexible, overcomes some shortcomings of the existing models, and performs well in the selected verification cases.