This digital dataset defines the well locations, perforated intervals, and time series of hydraulic-head observations used in the calibration of the transient hydrologic model of the Central Valley flow system. The Central Valley encompasses an approximate 50,000 square-kilometer region of California. The complex hydrologic system of the Central Valley is simulated using the U.S. Geological Survey (USGS) numerical modeling code MODFLOW-FMP (Schmid and others, 2006b). This simulation is referred to here as the Central Valley Hydrologic Model (CVHM) (Faunt, 2009). Utilizing MODFLOW-FMP, the CVHM simulates groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis from 1961-2003. The USGS and CA-DWR maintain databases of key wells in the Central Valley that are web-accessible (http://waterdata.usgs.gov and http://www.water.ca.gov/waterdatalibrary/, respectively). These data were combined to form a database of available water levels throughout the Central Valley from 1961 to 2003. More than 850,000 water-level altitude measurements from more than 21,400 wells have been compiled by the USGS or CA-DWR and have been entered into their respective databases. However, only a small portion of these wells have both sufficient construction information to determine the well-perforation interval and water-level measurements for the simulation period. For model calibration, water-level altitude data were needed that were (1) distributed spatially (both geographically and vertically) throughout the Central Valley; (2) distributed temporally throughout the simulation period (years 1961-2003); and (3) available during both wet and dry climatic regimes. From the available wells records, a subset of comparison wells was selected on the basis of perforation depths, completeness of record, climatic intervals, and locations throughout the Central Valley. Water-level altitude observations (19,725) for 206 wells were used as calibration targets during parameter estimation. The CVHM is the most recent regional-scale model of the Central Valley developed by the U.S. Geological Survey (USGS). The CVHM was developed as part of the USGS Groundwater Resources Program (see "Foreword", Chapter A, page iii, for details).

This digital dataset defines the well locations for hydraulic-head observations used in the calibration of the transient hydrologic model of the Central Valley flow system. The Central Valley encompasses an approximate 50,000 square-kilometer region of California. The complex hydrologic system of the Central Valley is simulated using the USGSs numerical modeling code MODFLOW-FMP (Schmid and others, 2006). This application is referred to here as the Central Valley Hydrologic Model (CVHM) (Faunt, 2009). Utilizing MODFLOW-FMP, the CVHM simulates groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis from 1961-2003. The USGS and DWR maintain databases of key wells in the Central Valley that are web-accessible (http://waterdata.usgs.gov and http://www.water.ca.gov/waterdatalibrary/, respectively). These data were combined to form a database of available water levels throughout the Central Valley from 1961 to 2003. More than 850,000 water-level altitude measurements from more than 21,400 wells have been compiled by the USGS or DWR and have been entered into their respective databases. However, only a small proportion of these wells have both sufficient construction information to determine the well-perforation interval and water-level measurements for the simulation period. For model calibration, water-level altitude data were needed that were (1) distributed spatially (both geographically and vertically) throughout the Central Valley, from the valley trough to the foothills; (2) distributed temporally throughout the simulation period (1961-2003); and (3) available during both wet and dry climatic regimes. From the available wells records, a subset of comparison wells was selected on the basis of perforation depths, completeness of record, climatic intervals, and locations throughout the Central Valley. Water-level altitude observations (19,725) for 206 comparison wells were used as calibration targets during parameter estimation. The CVHM is the most recent regional-scale model of the Central Valley developed by the U.S. Geological Survey (USGS).The CVHM was developed as part of the USGS Groundwater Resources Program (see "Foreword", Chapter A, page iii, for details).

This digital dataset defines the model grid, active model cells in the 10 model layers, and hydraulic-head values in the 10 model layers used to initiate the transient hydrologic model of the Central Valley flow system. The Central Valley encompasses an approximate 50,000 square-kilometer region of California. The complex hydrologic system of the Central Valley is simulated using the USGS numerical modeling code MODFLOW-FMP (Schmid and others, 2006). This simulation is referred to here as the Central Valley Hydrologic Model (CVHM) (Faunt, 2009). Utilizing MODFLOW-FMP, the CVHM simulates groundwater- and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis from 1961-2003. The total active modeled area is 20,334 square-miles on a finite-difference grid comprising 441 rows and 98 columns. Slightly less than 50 percent of the cells are active. The CVHM grid has a uniform horizontal discretization of 1x1 square mile and is oriented parallel to the valley axis, 34 degrees west of north (Faunt, 2009). The starting heads are based on the water table and potentiometric surface developed by Williamson and others (1989). The CVHM is the most recent regional-scale model of the Central Valley developed by the U.S. Geological Survey (USGS). The CVHM was developed as part of the USGS Groundwater Resources Program (Faunt, 2009. See "Foreword", Chapter A, page iii, for details).

This digital dataset defines the spring 1961 hydraulic head in the lower pumped zone of California's Central Valley. It was used to initiate the water-level altitudes for the lower zones of the transient hydrologic model of the Central Valley flow system. The Central Valley encompasses an approximate 50,000 square-kilometer region of California. The complex hydrologic system of the Central Valley is simulated using the USGS numerical modeling code, MODFLOW-FMP (Schmid and others, 2006). This simulation is referred to here as the Central Valley Hydrologic Model (CVHM) (Faunt, 2009). Utilizing MODFLOW-FMP, the CVHM simulates groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis from 1961-2003. The starting heads are based on the water-table and potentiometric surface developed by Williamson and others (1989). Maps of the spring 1961 water-table and hydraulic head in the lower pumped zone are shown in Figure 31 of Williamson and others (1989). The CVHM is the most recent regional-scale model of the Central Valley developed by the U.S. Geological Survey (USGS). The CVHM was developed as part of the USGS Groundwater Resources Program (Faunt, 2009. See "Foreword", Chapter A, page iii, for details).

This digital dataset defines the spring 1961 hydraulic head in the lower pumped zone of California's Central Valley. It was used to initiate the water-level altitudes for the lower zones of the transient hydrologic model of the Central Valley flow system. The Central Valley encompasses an approximate 50,000 square-kilometer region of California. The complex hydrologic system of the Central Valley is simulated using the USGS numerical modeling code, MODFLOW-FMP (Schmid and others, 2006). This simulation is referred to here as the Central Valley Hydrologic Model (CVHM) (Faunt, 2009). Utilizing MODFLOW-FMP, the CVHM simulates groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis from 1961-2003. The starting heads are based on the water-table and potentiometric surface developed by Williamson and others (1989). Maps of the spring 1961 water-table and hydraulic head in the lower pumped zone are shown in Figure 31 of Williamson and others (1989). The CVHM is the most recent regional-scale model of the Central Valley developed by the U.S. Geological Survey (USGS). The CVHM was developed as part of the USGS Groundwater Resources Program (Faunt, 2009. See "Foreword", Chapter A, page iii, for details).

This digital dataset defines the model-grid and hydraulic-property data arrays of the Multiplier (MULT) Package used in the transient hydrologic model of the Central Valley flow system. The MULT package defines multiplier arrays for calculation of model-layer characteristics from parameter values. The Central Valley encompasses an approximate 50,000 square-kilometer region of California. The complex hydrologic system of the Central Valley is simulated using the USGS numerical modeling code, MODFLOW-FMP (Schmid and others, 2006). This simulation is referred to here as the Central Valley Hydrologic Model (CVHM) (Faunt, 2009). Utilizing MODFLOW-FMP, the CVHM simulates groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis from 1961-2003. The total active modeled area is 20,334 square-miles on a finite-difference grid comprising 441 rows and 98 columns. Slightly less than 50 percent of the cells are active. It has a uniform horizontal discretization of 1x1 square mile and is oriented parallel to the valley axis, 34 degrees west of north (Faunt, 2009). The MULT Package includes the percentage of coarse-grained deposits in each of the 10 model layers, specific yield, and the altitudes of the tops of model layers 1-4. In order to better characterize the aquifer-system deposits, lithologic data from approximately 8,500 drillers' logs of boreholes ranging in depth from 12 to 3,000 feet below land surface were compiled and analyzed. The percentage of coarse-grained sediment, or texture, then was computed for each 50-foot depth interval of the drillers' logs. A 3-dimensional texture model was developed by interpolating the percentage of coarse-grained deposits onto a 1-mile spatial grid at 50-foot depth intervals from land surface to 2,800 feet below land surface. The specific yield data were extrapolated from the percentage of coarse-grained deposits in model layer 1. The CVHM is the most recent regional-scale model of the Central Valley developed by the U.S. Geological Survey (USGS). The CVHM was developed as part of the USGS Groundwater Resources Program (see "Foreword", Chapter A, page iii, for details).

This digital dataset contains the name and location for the diversions from the surface-water network for the Central Valley Hydrologic Model (CVHM). The Central Valley encompasses an approximate 50,000 square-kilometer region of California. The complex hydrologic system of the Central Valley is simulated using the USGS numerical modeling code MODFLOW-FMP (Schmid and others, 2006). This simulation is referred to here as the CVHM (Faunt, 2009). Utilizing MODFLOW-FMP, the CVHM simulates groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis from 1961-2003. The total active modeled area is 20,334 square-miles. The CVHM includes complex surface-water management processes. The hydrology of the present-day Central Valley and the CVHM model are driven by surface-water deliveries and associated groundwater pumpage. The Streamflow Routing Package (SFR1) is linked to MODFLOW-FMP to facilitate the simulated conveyance of surface-water deliveries. If surface-water deliveries do not meet the farm-delivery requirement, the FMP invokes simulated groundwater pumping to meet the demand. The surface-water network represents a subset of the entire stream network in the valley. Even so, it covers about 3,000 kilometers of surface-water and is simulated using 208 stream segments that represent 2244 stream reaches, with 43 inflows and 66 diversion locations providing 64 routed and 41 non-routed deliveries. Most of these inflows are regulated by dams and most of the deliveries are conveyed through an extensive canal network. The routed deliveries are conveyed through the simulated surface-water network, while the non-routed delivery conveyance typically occurs through small canals or diversion ditches and are not directly simulated. Much of the surface-water diversion and delivery information was compiled by the California Department of Water Resources (DWR) for 21 water-balance subregions (WBSs) covering the valley floor (C. Brush, California Department of Water Resources, written commun., February 21, 2007). The CVHM is the most recent regional-scale model of the Central Valley developed by the U.S. Geological Survey (USGS). The CVHM was developed as part of the USGS Groundwater Resources Program (see "Foreword", Chapter A, page iii, for details).

This digital dataset contains the name and location for the diversions from the surface-water network for the Central Valley Hydrologic Model (CVHM). The Central Valley encompasses an approximate 50,000 square-kilometer region of California. The complex hydrologic system of the Central Valley is simulated using the USGS numerical modeling code MODFLOW-FMP (Schmid and others, 2006). This simulation is referred to here as the CVHM (Faunt, 2009). Utilizing MODFLOW-FMP, the CVHM simulates groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis from 1961-2003. The total active modeled area is 20,334 square-miles. The CVHM includes complex surface-water management processes. The hydrology of the present-day Central Valley and the CVHM model are driven by surface-water deliveries and associated groundwater pumpage. The Streamflow Routing Package (SFR1) is linked to MODFLOW-FMP to facilitate the simulated conveyance of surface-water deliveries. If surface-water deliveries do not meet the farm-delivery requirement, the FMP invokes simulated groundwater pumping to meet the demand. The surface-water network represents a subset of the entire stream network in the valley. Even so, it covers about 3,000 kilometers of surface-water and is simulated using 208 stream segments that represent 2244 stream reaches, with 43 inflows and 66 diversion locations providing 64 routed and 41 non-routed deliveries. Most of these inflows are regulated by dams and most of the deliveries are conveyed through an extensive canal network. The routed deliveries are conveyed through the simulated surface-water network, while the non-routed delivery conveyance typically occurs through small canals or diversion ditches and are not directly simulated. Much of the surface-water diversion and delivery information was compiled by the California Department of Water Resources (DWR) for 21 water-balance subregions (WBSs) covering the valley floor (C. Brush, California Department of Water Resources, written commun., February 21, 2007). The CVHM is the most recent regional-scale model of the Central Valley developed by the U.S. Geological Survey (USGS). The CVHM was developed as part of the USGS Groundwater Resources Program (see "Foreword", Chapter A, page iii, for details).

This digital dataset contains the name and location for the inflows to the surface-water network for the Central Valley Hydrologic Model (CVHM). The Central Valley encompasses an approximate 50,000-square-kilometer region of California. The complex hydrologic system of the Central Valley is simulated using the USGS numerical modeling code MODFLOW-FMP (Schmid and others, 2006b). This simulation is referred to here as the CVHM (Faunt, 2009). Utilizing MODFLOW-FMP, the CVHM simulates groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis from 1961-2003. The total active modeled area is 20,334 square-miles. The CVHM includes complex surface-water management processes. The hydrology of the present-day Central Valley and the CVHM model are driven by surface-water deliveries and associated groundwater pumpage. The Streamflow Routing Package (SFR1) is linked to MODFLOW-FMP to facilitate the simulated conveyance of surface-water deliveries. If surface-water deliveries do not meet the farm delivery requirement, the FMP invokes simulated groundwater pumping to meet the demand. The surface-water network represents a subset of the entire stream network in the valley. Even so, it covers about 3,000 kilometers of surface-water and is simulated using 208 stream segments that represent 2244 stream reaches, with 43 inflows and 66 diversion locations providing 64 routed and 41 non-routed deliveries. Most of these inflows are regulated by dams and most of the deliveries are conveyed through an extensive canal network. The routed deliveries are conveyed through the simulated surface-water network, while the non-routed delivery conveyance typically occurs through small canals or diversion ditches and are not directly simulated. Much of the surface-water diversion and delivery information was compiled by the California Department of Water Resources (DWR) for 21 water-balance subregions (WBSs) covering the valley floor (C. Brush, California Department of Water Resources, written commun., February 21, 2007). The CVHM is the most recent regional-scale model of the Central Valley developed by the U.S. Geological Survey (USGS). The CVHM was developed as part of the USGS Groundwater Resources Program (see "Foreword", Chapter A, page iii, for details).

This digital geospatial data set contains the locations, values, and uncertainties of 700 hydraulic-head observations used in the steady-state, prepumped period of the transient model of the Death Valley regional ground-water flow system (DVRFS), a 100,000-square-kilometer region of southern Nevada and California. Hydraulic-head observations, which are the composite of one or more water-level measurements made at a well, are used to calibrate ground-water flow models. To develop hydraulic- head observations for the DVRFS ground-water flow model, nearly all available water levels for the DVRFS region through 2004 were compiled in Ground-Water Site Inventory (GWSI), the ground-water component of the U.S. Geological Survey (USGS) National Water Information System (NWIS) database. Water levels suitable for developing hydraulic-head observations representative of regional, steady-state ground-water flow conditions were identified through analyses. The resulting water levels were averaged for each well to produce one hydraulic-head observation value at each of 700 wells. The uncertainty of each hydraulic-head observation was statistically quantified from the values of uncertainties associated with well altitude and location, nonsimulated transient stress, and measurement accuracy.