Simulating Runoff and Sediment Yield on Semiarid Watersheds

by V. L. Lopes, Univ of Arizona, United States,
L. J. Lane, Univ of Arizona, United States,



Document Type: Proceeding Paper

Part of: Watershed Planning and Analysis in Action

Abstract: This paper describes a computer program called WESP (Watershed Erosion Simulation Program), a physically-based, distributed parameter, event-oriented, one-dimensional numerical model for simulating surface runoff and sediment yield on small semiarid watersheds. The program includes components for computing rainfall excess rates, broad sheet flow (interrill flow), concentrated flow (rill and stream channel flow), erosion, sediment transport, and deposition. Rainfall excess is computed using the W.H. Green & G.A. Ampt equation with the ponding time calculation for an unsteady rainfall. The broad sheet and concentrated flow components are based on the kinematic wave equations. The sediment yield component is based on nonequilibrium dynamic sediment transport equations for simultaneous rates of entrainment and deposition. The model was tested using sediment yield data from rainfall simulator plots and small semiard watersheds in Tombstone, Arizona.

Subject Headings: Sediment | Watersheds | Computer models | Sheet flow | Flow simulation | Sediment transport | Channel flow | Runoff | Arid lands | Computer software | Arizona | North America | United States

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