Integrated Watershed Modeling

In the past 30 years, lumped-parameter watershed models have been employed for integrated surface water and groundwater modeling to calculate surface and base runoffs. Physics-based, process-level models that employ consistent sets of governing equations for integrated overland, river, vadose, and groundwater flow have been practically nonexistent until early 1990s. This paper presents the development of an integrated media, physics-based watershed model. Complete coupling simulations among system components of land surfaces, river networks, vadose zones, and groundwater or partial couplings between any two components can be conducted with the model. Various rigorous coupling strategies based on physics and numerics for interactions among these components are described. Two examples were employed to discuss the issues of coupling. One was used to demonstrate differences and implications between continuity and linkage approaches when the surface water and groundwater are in direct connection. Another one, a watershed modeling in Florida, was used to illustrate that complete and partial couplings yield quite different simulations.