The Central Valley, and particularly the San Joaquin Valley, has a long history of land subsidence caused by groundwater development. The extensive withdrawal of groundwater from the unconsolidated deposits of the San Joaquin Valley lowered groundwater levels and caused widespread land subsidence—reaching 9 meters by 1981. More than half of the thickness of the aquifer system is composed of fine-grained sediments, including clays, silts, and sandy or silty clays that are susceptible to compaction. In an effort to aid water managers in understanding how water moves through the aquifer system, predicting water-supply scenarios, and addressing issues related to water competition, the United States Geological Survey (USGS) developed a new hydrologic modeling tool, the Central Valley Hydrologic Model (CVHM; Faunt and others 2009). The data presented in this data release will be used to facilitate updates to the original CVHM and represent subsidence and aquifer-system compaction observations (measurements) using various methods during 1926–2018. In the context of this report, subsidence is defined as the lowering of the land-surface elevation as a result of aquifer-system compaction and is calculated by differencing repeated elevation measurements derived from geodetic surveys, continuous GPS (CGPS), and Interferometric Synthetic Aperture Radar (InSAR) techniques. Aquifer-system compaction is measured using vertical borehole extensometers to monitor changes in the distance between the top of a cable or pipe that is anchored or placed at depth, and a reference point at or near land surface. For more detailed information on the methods discussed in this data release, please see Sneed and others, 2013; 2018).

The updated Central Valley Hydrologic Model (CVHM2) is similar to the original Central Valley Hydrologic Model (CVHM) in terms of the basic units of model discretization. Both versions simulated monthly stress periods on the same one square mile cell spatial discretization. Although the simulation period for CVHM1 was water years 1962-2003, the CVHM2 simulation period is water years 1962-2019. Both CVHM and CVHM2 have a 6 month spin up period from April-September of 1961. The CVHM2 is now composed of 13 layers compared to the ten in the CVHM. As in CVHM, hydraulic properties are generally based on percentage of coarse-grained deposits and these values are adjusted based on depth, spatial location (geomorphic province), and geologic units as described by Faunt and others (2009).

This digital dataset includes three sets of observational data (groundwater level, streamflow, subsidence) used to calibrate the updated Central Valley Hydrologic Model (CVHM2). CVHM2 is a tool that can be used to quantify the sustainability of groundwater resources in the Central Valley.

This data release provides updated borehole information to build upon and further refine a three-dimensional (3-D) texture model of valley-fill deposits in the Central Valley created by Faunt and others (2009). This model aids in understanding the aquifer system of the entire valley and will be later utilized in a groundwater flow model. The original database contained approximately 8,500 boreholes and with the addition of new data, the model now contains 14,683 boreholes. The new borehole lithologic data was sourced from the California Department of Water Resources (DWR) Online System of Well Completion Reports (OSWCR) and the California Central Valley Groundwater-Surface Water Simulation Model (C2VSim). This dataset contains (1) tabular data of individual borehole general location and construction information, (2) downhole lithologic interval data derived from well driller’s lithology logs and parsed to a series of textural descriptors.

This digital dataset contains datasets used to develop the Multi Node Well (MNW2) Package in CVHM2. It includes well locations, well properties for Municipal Pumping, Rural Pumping, Recovery Pumping, and Agricultural Pumping. The data release also includes pumping rates for Municipal Pumping, Rural Pumping, Recovery Pumping. Agricultural Pumping are estimated in CVHM2 by the farm process, and thus are not included in the virtual farm well child item. The data release also documents how urban water use was estimated in CVHM2 from population and other base datasets.

This digital dataset contains the soil data for the updated Central Valley Hydrologic Model (CVHM2). The soil data is based on California Department of Water Resource’s C2VSim’s fine grid model soil curve number data set (C2VSimFG Version 1.0 - Datasets; CNRA, 2011). These values were originally obtained from the U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey Geographic Database (SSURGO) soil map of the State of California (USDA, 2004), and then an area-weighted average value for each hydrologic soil group within each subregion was calculated to the C2VSim element. Curve number values obtained from SSURGO were converted for use in C2VSimFG. To translate the curve number from the C2VSim grid to the CVHM2 grid, the curve number from the C2VSim that covered the largest area of a CVHM2 cell was used as zone number. There were 8 unique curve numbers in C2VSimFG. Then each of these numbers were given a different zone number for each of the four regions (Sacramento, Delta-Eastside, San Joaquin, and Tulare), resulting in 26 unique zones for CVHM2. The use of regional zones for curve numbers along with that introduced by the large scale of cell sizes (one square mile) introduces some unavoidable errors into the calculations, but this is expected for errors inherent in estimating runoff rates over such a large area without using a dedicated and complex model (Loague and Freeze, 1985).

This digital dataset contains groundwater level observations for 364 wells, in addition to well construction information, from 1916 to 2014 in the Central Valley, California. Groundwater level observations are used to create groundwater level contours and to calibrate the groundwater levels for the updated Central Valley Hydrologic Model (CVHM2). Groundwater level observations were collected from five sources (USGS, 2018; SLDMWA, 2018; CADWR, 2004; CRNA, 2018).

This digital dataset contains the municipal pumping dataset used to develop the Multi Node Well (MNW2) Package in the updated Central Valley Hydrologic Model (CVHM2). It includes well locations, well properties, and pumping rates for Municipal Pumping.

The model setup of the updated Central Valley Hydrologic Model (CVHM2) is similar to the original Central Valley Hydrologic Model (CVHM). The differences in the model setup are described here as either model discretization, tidal influence, or drain flow. For model discretization, CVHM2 has 13 layers compared to 10 in CVHM. Tidal data for the San Francisco Bay and its influence on the general head boundary was added in CVHM2. Drain flow was not included in CVHM1 for the west side of the San Joaquin Valley, and was added in CVHM2.

This digital dataset contains the rural pumping dataset used to develop the Multi Node Well (MNW2) Package in the updated Central Valley Hydrologic Model (CVHM2). It includes well locations, well properties, and pumping rates for rural pumping.