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Robert S Regan

Research, development and application of the PRMS, GSFLOW, and MODSIM-GSFLOW modeling codes and National Hydrologic Modeling Infrastructure


U.S. Geological Survey

Denver Federal Center, Box 25046, MS 412

Denver, Colorado 80225



Masters of Divinity (2000). Wesley Theological Seminary, Washington, D.C.

BA Environmental Science (1987). University of Virginia, Charlottesville, Virginia,


DATES From: 2003 To: Present

DESCRIPTION: Research, development, and applications focuses on incorporating new simulation algorithms and enhancements of existing algorithms within the Precipitation-Runoff Modeling System (PRMS), the coupled Modular Groundwater Flow Model (MODFLOW) and PRMS simulation model—GSFLOW, the coupled MODSIM-GSFLOW simulation code, and the National Hydrologic Modeling (NHM) Infrastructure. Development is driven by WMA research objectives of improving the understanding and simulation of watershed-scale hydrologic processes to climate and anthropogenic influences, environmental characteristics with input and requests from USGS and other Federal agencies, the academic community, and private sector scientists.



Research and development of the PRMS simulation model, most recently developing methods for input of historic and projected climate; dynamic parameters; and water-use information and enhancement of surface-depression storage and spatial and temporal characterization of model parameters for use in large model domains.

Research and development of the coupled groundwater/surface-water simulation model (GSFLOW) and MODFLOW UZF and AG Package, and MODSIM-GSFLOW coupled simulation code.

Research and development of a loosely-coupled, sub-daily simulation model using PRMS, NOAA-NWS Lag and K river routing model, and USACE HEC-ResSim Reservoir System Simulation model for a large watershed spanning portions of NY, NJ, and PA.


Hydrologist, member of the Modeling of Watershed Systems (MoWS) project, USGS National Research Program, Central Region, Lakewood, Colorado (2003-2016)

Senior Pastor, Greenwood United Methodist Church, Winchester, Virginia (1999-2002)

Hydrologist, project chief and member of the Hydrologic Analysis Software Support Section, Reston, Virginia (1992-1996)

Computer Scientist, project chief and site admistrator USGS National Research Program, Northeast Region, Office of Surface Water, Office of Groundwater, and Office of Water Quality, Reston, Virginia (1986-1992)

Hydrologist, member of the Modeling of Hydrodynamic Systems project, USGS National Research Program, Northeast Region, Reston, Virginia (1981-1986)