The beta version of the Fine Grid California Central Valley Groundwater-Surface Water Simulation Model (C2VSimFG Beta) is a computer program that simulates water movement through the linked land surface, groundwater, and surface water flow systems in California’s Central Valley using the DWR-developed software, Integrated Water Flow Model Version 2015 (IWFM-2015). C2VSimFG Beta contains monthly historical stream inflows, surface water diversions, precipitation, evapotranspiration, and land use acreages from October 1973 through September 2015 (Data is available in the input files for 1922 through 2015).
C2VSimFG Beta dynamically calculates crop water demands, allocates contributions from precipitation, soil moisture and surface water diversions, and calculates the groundwater pumpage required to meet the remaining demand. It simulates the historical response of the Central Valley’s groundwater and surface water flow system to historical stresses, and can also be used to simulate the response to projected stresses. DWR is providing C2VSimFG Beta to Groundwater Sustainable Agencies (GSAs) and other related entities as an optional tool that can be used to perform analysis during development and implementation of their Groundwater Sustainability Plans (GSPs).
C2VSimFG Beta has a finite element grid with over 35,000 elements. The model has a typical run-time of approximately 6 hours. Model input data have been specified on a per element basis based on available information. The model elements are also grouped into 21 water budget subregions for estimating regional water budgets. The C2VSimFG Beta model has undergone limited calibration of the land surface budgets and aquifer parameters. A calibrated version of C2VSimFG is expected in Fall 2018.
One of the purposes of the C2VSimFG Beta is for GSAs to be able to review and verify the input data in the model. In many cases, it may be appropriate to update the model further using local knowledge and information. The locally revised model may then provide a closer estimate of the total water budget in a groundwater basin or subbasin and be able to more closely simulate the local hydrogeological response due to management and use.