SHETRAN: Distributed River Basin Flow and Transport Modeling System

Physically based spatially distributed (PBSD) river basin models have been available for over 10 years. One of their strengths lies in the way the surface and subsurface are represented as coupled parts of a whole, giving ground-water flows that are controlled by such factors as realistic surface saturation and infiltration, and surface conditions that are controlled by realistic groundwater levels, discharges, and so forth. PBSD sediment and solute transport models can be integrated into PBSD river basin modeling systems, and the integrated systems are powerful tools for studying the environmental impacts associated with land erosion, pollution, and the effects of changes in land use and climate, and also in studying surface-water and ground-water resources and their management. SHETRAN takes PBSD river basin modeling a step further, in that multifraction sediment transport and multiple, reactive solute transport are handled within a single system, fully coupled to water flow, and the subsurface is modeled as a fully 3D variably saturated heterogeneous medium. SHETRAN therefore has a substantial capability for addressing environmental and water resources problems that span the traditional disciplines of river basin and groundwater modeling.