Products: Integrated Groundwater and Surface Water Model (IGSM)

The IGSM is a comprehensive hydrologic model that simulates both surface water and groundwater flow systems, including the land surface processes, such as crop consumptive use. Originally developed by researchers at the University of California at Los Angeles (UCLA), IGSM has been upgraded to a state-of-the- art comprehensive hydrologic modeling system through numerous project applications in California, other states in the U.S.A., and in Europe. The latest version of IGSM is Version 6.0, which was completed in 2003, under the sponsorship of the Department of Water Resources (WRIME, 2003). Main features of IGSM are outlined on this sheet. For detailed description of IGSM capabilities and features refer our web site at www.wrime.com and click on the Integrated Modeling link.

WRIME, Inc., offers expert services in integrated modeling of surface water systems and groundwater systems.  The two principals of WRIME, Inc., Dr. Saquib Najmus and Dr. Ali Taghavi, are the co-authors of the Integrated Groundwater and Surface water Model (IGSM), which has been widely used in California by federal, state, and local agencies.

The IGSM is a modeling tool that includes numerous options and algorithms for implementing the main model features, including groundwater simulation using a finite element quasi-three-dimensional methodology in a multiple layer aquifer system; stream flow simulation and stream-aquifer interaction simulation; rainfall/runoff simulation algorithms for surface hydrologic processes, infiltration, percolation, and evapotranspiration; simulation of soil moisture accounting and unsaturated flow to integrate surface and subsurface hydraulic and hydrologic processes; estimation of agricultural water demands using crop consumptive methodology that relies on regional land use, evapotranspiration rates, minimum soil moisture requirements, and irrigation efficiencies. In addition, the IGSM simulates the operation of river/reservoir system by computing reservoir storage and releases to meet downstream diversions and/or minimum in-stream flow requirements. The land subsidence module is based on theory of aquifer compaction and simulates the changes in aquifer storage due to permanent compaction of interbed layers as a result of groundwater pumping.