Description of the National Hydrologic Model for use with the Precipitation-Runoff Modeling System (PRMS)

Abstract

This report documents methods to derive the Precipitation-Runoff Modeling System (PRMS) parameter values as used in the U.S. Geological Survey (USGS) National Hydrologic Model (NHM). These parameter values are available from the NHM Parameter Database. Spatial subsets of the NHM Parameter Database, that is individual watersheds derived on the basis of stream segment or USGS streamgage identification numbers, can be retrieved using the NHM Bandit software tool. This report relies heavily upon (1) USGS Techniques and Methods, book 6, chapter B7 (Markstrom and others, 2015, https://dx.doi.org/10.3133/tm6b7) that documents PRMS-IV and (2) USGS Techniques and Methods, book 6, chapter B4 that documents the GIS Weasel (Viger and Leavesley, 2007, https://pubs.usgs.gov/tm/2007/06B04/). Summaries of changes to input and output values for the PRMS are available on the PRMS software distribution page (https://wwwbrr.cr.usgs.gov/projects/SW_MoWS/PRMS.html, accessed September 30, 2017) by selecting, "Changes in the specification of user inputs are reported as updates to tables in the Users' Manual (tables 2, 1-2, 1-3, and 1-5)" under Information. Changes in these tables since the publication of the PRMS-IV documentation report are highlighted in various colors. This report provides brief descriptions of the PRMS, the NHM, and the Geospatial Fabric for National Hydrologic Modeling (https://wwwbrr.cr.usgs.gov/projects/ SW_MoWS/GeospatialFabric.html, accessed September 30, 2017) upon which the NHM is discretized.