MODFLOW2000_FMP1_1 model used to simulate the groundwater flow of the Central Valley Aquifer, California

Abstract

A three-dimensional groundwater flow model (MODFLOW200-FMP1_1) of the Central Valley in California was developed to aid water managers in understanding how water moves through the aquifer system, to predict water-supply scenarios, and to address issues related to water competition. The USGS Groundwater Resources Program made a detailed assessment of groundwater availability of the Central Valley aquifer system, which includes: (1) the present status of groundwater resources; (2) how these resources have changed over time; and (3) tools to assess system responses to stresses from future human uses and climate variability and change. This effort builds on previous investigations, such as the USGS Central Valley Regional Aquifer System and Analysis (CV-RASA) project and several other groundwater studies in the Valley completed by Federal, State and local agencies at differing scales. The principal product of this new assessment is a tool referred to as the Central Valley Hydrologic Model (CVHM) that accounts for integrated, variable water supply and demand, and simulates surface-water and groundwater-flow across the entire Central Valley system. The current model was extended to incorporate a slightly larger geographic area, has a finer spatial and temporal discretization, uses a more-detailed depiction of subsurface geology. In addition, the model utilizes a modified version of MODFLOW2000 (version 1.15.03) to include an updated and refined Farm Process (FMP!) to simulate groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis for April 1961 through September 2003. This USGS data release contains all of the input and output files for the simulation and calibration of the CVHM described in the associated model documentation report (https://pubs.er.usgs.gov/publication/pp1766).