Reclamation Information Sharing Environment (RISE)

Heavy rainfall and subsequent sediment and mercury movement from watersheds have serious economic, environmental and social impacts on communities around the world. Hydrological models have become useful decision support tools for flood warning, watershed management and mercury delivery to reservoirs. The development of a process-based, mesh-distributed watershed model, however, is complex as it involves a range of disciplines and spans multiple spatial and temporal scales. In this research, a process-based and mesh-distributed model, suitable for both event-based and continuous simulations, was developed. The watershed is conceptualized in three distinct zones: a surface region and two subsurface zones representing the unsaturated soil and groundwater. Overland runoff is governed by the 2D diffusive wave equation with an optional 1D channel network solver; water in the unsaturated zone is modeled through mass conservation assuming dominant vertical processes; and the saturated groundwater flow is governed by the 2D Dupuit approximation. Soil erosion and sediment transport are governed by multi-size non-equilibrium equations incorporating the processes of soil entrainment, deposition and transport. The mercury is routed using also the mass conservation equation. The model is driven by meteorological input, taking into account vegetation characteristics to compute evaporation and plant transpiration, and land use and soil type properties. The new model represents a generalization of the existing models in an attempt to overcome some of the current model shortcomings.