PRMS version 5.0.0: Precipitation-Runoff Modeling System

The need to assess the effects of variability in climate, biota, geology, and human activities on water availability and flow requires 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 are: (1) simulate hydrologic processes including evaporation, transpiration, runoff, infiltration, and interflow as determined by the energy and water budgets of the plant canopy, snowpack, and soil zone 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.

This major release adds new functionality for: (a) input of dynamic parameters and water use data; (b) Muskingum streamflow routing with simulation of lakes; (c) output of subbasin, stream segment, and basin variables to Comma-Separated-Variable (CSV) files; (d) an option to compute potential evapotranspiration by using the Penman-Monteith formulation on the basis of specified windspeed and humidity data in the Data File; and (e) distribution of air temperature on the basis of specified minimum and maximum data in the Data File. Also, corrected major bugs in the potet_pm and potet_pt modules and minor bugs in the soilzone and gwflow modules.