The Precipitation Runoff Modeling System (PRMS) version 5.2.1.1

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, water use, and land use on streamflow and general watershed hydrology. The primary objectives of PRMS are: (1) simulate hydrologic processes including evaporation, transpiration, snow accumulation and melt, 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 (maximum and minimum air temperature and precipitation, and depending on climate distribution options selected, potential evapotranspiration, solar radiation, humidity, and windspeed); (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 release documents describe updates to the PRMS software from previous release through version 5.2.1.1.

The PRMS is packaged for personal computers using one of the Linux or Microsoft Windows operating systems. An executable file compiled for 64-bit operating systems is provided. The Linux executable was compiled using the gfortran and gcc compilers (9.4.0 version). The Windows executable was compiled using the Microsoft Visual Studio Community 2022 (64-bit), Version 17.7.5 and the Intel Fortran version 2023.2 and Intel C++ Classic version 19.2 compilers.

Included with the release are several documents that use the Portable Document Format (PDF) file structure. The PDF files are readable and printable on various computer platforms using Acrobat Reader from Adobe. The Acrobat Reader is freely available from the following World Wide Web site: http://www.adobe.com/

IMPORTANT: Users should review the file .\Release_notes_prms_5.2.1.1.pdf for a description of, and references for, and changes that have been introduced into PRMS with each official release; these changes may substantially affect model results. See file .\PRMS_tables_5.2.1.1.pdf that provides replacements tables 2, 1-1, 1-2, 1-3, 1-4, and 1-5 in Markstrom and others, 2015 that documented the Precipitation Runoff Modeling System (PRMS) version 4.0.3. A new table is included that documents variables that can be input in Climate-By-HRU Files.