_(Released November 17, 2022)_ The California Central Valley Groundwater–Surface Water Simulation Model - Coarse Grid (C2VSimCG) is an integrated hydrologic model that simulates the movement of water through the linked land surface, groundwater, and surface water flow systems in the 20,000 square mile area defined by the alluvial Central Valley Aquifer. C2VSimCG was developed using the Integrated Water Flow Model (IWFM2015) application, an open-source software package that couples a three-dimensional finite element groundwater flow simulation component with one-dimensional land surface, stream flow, lake, unsaturated zone, and small-stream watershed components. C2VSimCG Version 1.0 dynamically calculates crop water demands, allocates contributions from precipitation, soil moisture and surface water diversions, and calculates the supplementary groundwater pumping required to meet the remaining unmet consumptive water demands. The model simulates the response of the Central Valley’s groundwater and surface water flow system to predefined stresses and can also be used to simulate the alternative scenarios. Two applications of the C2VSimCG v1.0 are available: __Historical Run:__ Simulates the historical period for water years 1974 through 2015. The input data uses historical values for precipitation, land use, evapotranspiration, reservoir releases, and surface water diversions. Required groundwater pumping is computed dynamically. __Baseline Runs:__ The baseline model represents “Existing Conditions” and serves as a representation of the historical hydrology with a current level of land use development and water demands. The C2VSimCG Baseline model can be run with two sets of initial conditions for groundwater levels: pre-drought conditions (representing Fall 2010-2012) and post-drought conditions (representing Fall 2018-2020). Each simulation runs for water years 1922-2015, a period of 94 years.

,

The original Central Valley Hydrologic Model (CVHM) did not simulate tile drain discharge in the west side of the San Joaquin Valley. The updated Central Valley Hydrologic Model (CVHM2) does simulate on-farm drains. The data for the drain flow and locations were obtained from the Berkeley National Laboratory is from (WESTSIM2) (N. Quinn, Berkeley National Laboratory, written communication., 2010). This component of the data release includes:e (1) three datasets included are a spreadsheet of the available observations with the drain flows in acre-ft/month, (2) a shapefile of the WESTSIM2 drain cells, and (3) a shapefile of the original WESTSIM2 drain cells translated to the CVHM2 model grid.

This digital dataset contains the surface water data used for both the Salinas Valley Watershed Model (SVWM) and the Lower Salinas Valley Hydrologic Models (Salinas Valley Integrated Hydrologic Model (SVIHM) and Salinas Valley Operational Model (SVOM)). The surface water dataset includes two regions of the Salinas River Watershed; the upper region is primarily within San Luis Obispo County, California and lower region of the Salinas River Watershed is contained within Monterey County, California. Subcatchments within the Salinas River watershed were delineated using the U.S. Geological Survey (USGS) 10m digital elevation model (DEM), USGS National Hydrography Dataset Best Resolution (NHD) watershed boundaries, and the NHD stream data (U.S. Geological Survey, 2019). For each defined subcatchment, a pourpoint was defined that connects the watershed outflow to the tributary streams or ephemeral stream channels defined for the Salinas River in the lower and upper Salinas Valley Watershed. For the stream network of the lower Salinas River Watershed, NHD defined streams were used to initially define the network. The lower Salinas River Watershed stream network was refined to account for diversion canals and undefined ephemeral channels that drain into the Lower Salinas Valley in cooperation with Monterey County. For the lower Salinas Valley, the stream network and subcatchment data were defined simultaneously. For the upper Salinas Valley the pourpoints were defined based upon where previously defined subcatchments intersected with the stream network defined by the Paso Robles Basin Model (Fugro West, Inc and Cleath Associates, 2002; Fugro West, Inc, ETIC Engineering, Inc, and Cleath and Associates, 2005). The stream network spatial data were not provided from San Luis Obispo County as a vector shape, and the USGS did not develop the Paso Robles Basin Model (PRBM), therefore a shapefile of locations where the PRBM grid contained a stream reach was used as a proxy for linear features of the stream network in the upper Salinas River Watershed. This data set includes the following files: - Shapefiles for stream network, both lower and upper watersheds - Streamflow gage data and location - Ungaged tributary inflow points, both lower and upper watersheds

,