Precipitation Runoff Modeling System (PRMS) version 5.2.0

The need to assess the effects of variability in climate, biota, geology, and human activities on water availability and flow can be assessed with computer models that simulate the hydrologic cycle at a watershed scale. The Precipitation-Runoff Modeling System (PRMS) is a deterministic, distributed-parameter, physical process-based modeling system developed to evaluate the response of various combinations of climate and land use on streamflow and general watershed hydrology. The primary objectives of PRMS are: (1) simulate hydrologic processes including evaporation, transpiration, runoff, infiltration, and interflow as determined by the energy and water budgets of the plant canopy, soil zone, and snowpack on the basis of distributed climate information (temperature, precipitation, and solar radiation); (2) simulate hydrologic water budgets at the watershed scale for temporal scales ranging from days to centuries; (3) integrate PRMS with other models used for natural-resource management or with models from other scientific disciplines; and (4) provide a modular design that allows for selection of alternative hydrologic-process algorithms from the standard PRMS module library. The PRMS version 5.2.0 includes an executable, source code, and examples problems.