Water Resources Applications Software

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Summary of PRMS

       prms - Precipitation-Runoff Modeling System

       PRMS is a modular-design, deterministic, distributed-parameter
       modeling system developed to evaluate the impacts of various
       combinations of precipitation, climate, and land use on streamflow,
       sediment yields, and general basin hydrology.  Basin response to
       normal and extreme rainfall and snowmelt can be simulated to
       evaluate changes in water-balance relationships, flow regimes, flood
       peaks and volumes, soil-water relationships, sediment yields, and
       ground-water recharge.  Parameter-optimization and sensitivity
       analysis capabilities are provided to fit selected model parameters
       and evaluate their individual and joint effects on model output.
       The modular design provides a flexible framework for continued
       model-system enhancement and hydrologic-modeling research and

       A watershed is divided into subunits based on such basin
       characteristics as slope, aspect, elevation, vegetation type, soil
       type, land use, and precipitation distribution.  Two levels of
       partitioning are available. The first divides the basin into
       homogeneous response units (HRU) based on the basin characteristics.
       Water and energy balances are computed daily for each HRU.  The sum
       of the responses of all HRU's, weighted on a unit-area basis,
       produces the daily system response and streamflow for a basin.  A
       second level of partitioning is available for storm hydrograph
       simulation.  The watershed is conceptualized as a series of
       interconnected flow planes and channel segments.  Surface runoff is
       routed over the flow planes into the channel segments; channel flow
       is routed through the watershed channel system.  An HRU can be
       considered the equivalent of a flow plane or it can be delineated
       into a number of flow planes.

       1991 version - Added option to output computed time series to the
          Watershed Data Management (WDM) file

       1984 version - A WDM file replaces the ISAM file for the time-series
          data management

       1983 version - Original version

       For daily streamflow computations, a minimum of daily precipitation
       and daily maximum and minimum air temperature are required.  For
       snowmelt computations, daily short-wave solar radiation data are
       recommended.  For areas without snowmelt, daily pan evaporation data
       can be substituted for temperature data.  For storm hydrograph and
       sediment computations, short time-interval precipitation,
       streamflow, and sediment data are needed.  Physical descriptive data
       on the topography, soils, and vegetation are input for each
       watershed subunit.  The spatial and temporal variation of
       precipitation, temperature and solar radiation are also needed.  The
       input time-series data are read from a WDM file.

       The observed (if available) and predicted mean daily discharge for
       the basin is output in tabular form.  Annual and monthly summaries
       of precipitation, interception, potential and actual
       evapotranspiration, and inflows and outflows of the ground water and
       subsurface reservoirs are available.  The time series available at a
       monthly time step may also be output at a daily time step along with
       the available soil moisture, percent snow cover, pack water
       equivalent, and snowmelt.  Most of the computed daily time series
       can also be written to the WDM file.  This information is also
       available for the individual HRU's.  A summary table of observed and
       predicted peak flows and runoff volumes for each storm period is
       output in tabular form. The inflow and outflow for user selected
       overland flow plans and channel segments can be output in tabular
       form, as "printer" plots, or to the WDM file.

       PRMS is written in Fortran 77 with the following extension: use of
       include files. Some variable and routine names are longer than 6
       characters. The UTIL, ADWDM, and WDM libraries from LIB are used. A
       subset of these libraries is provided with the code and may be used
       instead of the libraries; this subset uses INTEGER*4 and mixed type
       equivalence. For more information, see System Requirements in LIB.

       Leavesley, G.H., Lichty, R.W., Troutman, B.M., and Saindon, L.G.,
          1983, Precipitation-Runoff Modeling System: User's Manual:  U.S.
          Geological Survey Water-Resources Investigations Report 83-4238,
          207 p.

       Flynn, K.M., Hummel, P.R., Lumb, A.M., and Kittle, J.L., Jr., 1995,
          User's manual for ANNIE, version 2, a computer program for
          interactive hydrologic data management:  U.S. Geological Survey
          Water-Resources Investigations Report 95-4085, 211 p.

       Carey, W.P., and Simon, A., 1984, Physical basis and potential
          estimation techniques for soil erosion parameters in the
          Precipitation-Runoff Modeling System (PRMS):  U.S. Geological
          Survey Water-Resources Investigations Report 82-4218, 32 p.

       Cary, L.E., 1984, Application of the U.S. Geological Survey's
          Precipitation-Runoff Modeling System to the Prairie Dog Creek
          basin, Southeastern Montana: U.S. Geological Survey Water-
          Resources Investigations Report 84-4178, 98 p.

       Kidd, R.E., and Bossong, C.R., 1987, Application of the
          precipitation-runoff model in the Warrior Coal Field, Alabama:
          U.S. Geological Survey Water-Supply Paper 2036, 42 p.

       Kuhn, G., 1989, Application of the U.S. Geological Survey's
          Precipitation-Runoff Modeling System to Williams Draw and Bush
          Draw basins, Jackson County, Colorado:  U.S. Geological Survey
          Water-Resources Investigations Report 88-4013, 38 p.

       Norris, J.M., and Parker, R.S., 1985, Calibration procedure for a
          daily flow model of small watersheds with snowmelt runoff in the
          Green River coal region of Colorado:  U.S. Geological Survey
          Water-Resources Investigations Report 83-4263, 32 p.

       Parker, R.S., and Norris, J.M., 1989, Simulation of streamflow in
          small drainage basins in the southern Yampa River Basin,
          Colorado:  U.S. Geological Survey Water-Resources Investigations
          Report 88-4071, 47 p.

       Puente, C., and Atkins, J.T., 1989, Simulation of rainfall-runoff
          response in mined and unmined watersheds in coal areas of West
          Virginia:  U.S. Geological Survey Water-Supply Paper 2298, 48 p.

       Scott, A.G., 1984, Analysis of characteristics of simulated flows
          from small surface-mined and undisturbed Appalachian watersheds
          in the Tug Fork basin of Kentucky, Virginia, and West Virginia:
          U.S. Geological Survey Water-Resources Investigations Report
          84-4151, 169 p.

       Watershed Systems Modeling I (SW2008TC), offered annually at the
       USGS National Training Center.

       Operation and Distribution:
          U.S. Geological Survey
          Hydrologic Analysis Software Support Program
          437 National Center
          Reston, VA 20192

       Official versions of U.S. Geological Survey water-resources analysis
       software are available for electronic retrieval via the World Wide
       Web (WWW) at:


       and via anonymous File Transfer Protocol (FTP) from:

         (path: /pub/software).

       The WWW page and anonymous FTP directory from which the PRMS
       software can be retrieved are, respectively:

       annie(1) - Program to list, table, plot data in a WDM file
       iowdm(1) - Program to store time-series data in a WDM file
       wdm(1) - Watershed Data Management system

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