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i17 Delta Levees Anatomy 2007
The use of high-resolution LiDAR, and the products derived from it, allow for levee anatomy to be captured for the surveyed area. The resulting data is a catalog of precise levee location and components. This data can further be used for levee maintenance and management, flood modeling and prediction, as well as levee inventories. In the Delta Anatomy Mapping Project all levee anatomies were delineated using slope grids built from available LIDAR data points. LIDAR data points were converted to digital elevation models and subsequently into slope grids. Thresholds were identified that capture the levee crown, levee landside, levee waterside, ramps and toe ditches. Visual interpretations of slope thresholds were used in conjunction with heads-up digitizing to maintain smooth boundaries at a scale of 1:550. The delineation thresholds were derived from a combination of mapping scale, slope grid resolution and slope thresholds used for each anatomy classification. All anatomy has gone through an internal quality control process to ensure a minimum accuracy of +/- 3 feet. Anatomy was further reviewed and tested by DWR for compliance with an interpretive mapping standard of 80% accuracy. This data depicts the levee anatomy at the time of the LiDAR survey (2007) and are only accurate for that time. Users should be aware that temporal changes may have occurred since this data set was created and some parts of this data may no longer represent actual surface conditions. This version created by mapping from the 2007 Delta LIDAR. The associated data are considered DWR enterprise GIS data, which meet all appropriate requirements of the DWR Spatial Data Standards, specifically the DWR Spatial Data Standard version 3.1, dated September 11, 2019. DWR makes no warranties or guarantees — either expressed or implied — as to the completeness, accuracy, or correctness of the data. DWR neither accepts nor assumes liability arising from or for any incorrect, incomplete, or misleading subject data. Comments, problems, improvements, updates, or suggestions should be sent to GIS@water.ca.gov
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i12 Delta Hydrology
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,This point dataset represents the location of gaging stations in the Sacramento-San Joaquin Delta and Suisun Marsh that have historic and statistical hydrologic data, specifically various river stage data. Stages are given in NAVD88, units feet. Specific stages are given for peak stages, 100-year stages produced under 2 separate US Army Corps of Engineers hydrology reports from 1976 and 1992, the year of previous peak stages cited by the 1976 and 1992 reports, and approximate typical tidal values as approximately estimated based on long term data records. This 2023 version of this datset replaces the prior 2020 version, and should be used as a complete replacement. The underlying analyses did not change, but the USACE peak observed stage field names from the prior version were corrected and supplemental USACE 50- and 100-year stages were added accordingly. In addition, the vertical datum conversion used at specific gages was added. The vertical datum conversion is based on DWR survey and North Central Regional Office information that is maintained for each gage station. The stage data was compiled by Karen Tolentino, engineer with Delta Levees, and by Joel Dudas, Senior Engineer in DWR's Division of Engineering, based on a wide variety of sources, including the HYDSTRA database, various historic bulletins, raw data, station histories, and other information provided by DWR's North Central Region Office, USGS, and other misc sources. They also adjusted all data to approximate NAVD88-related stages. Observed data periods of record varied widely by station, but go back as far as 1905. All peak values were derived from start of records until up to May, 2017.,The associated data are considered DWR enterprise GIS data, which meet all appropriate requirements of the DWR Spatial Data Standards, specifically the DWR Spatial Data Standard version 3.5, dated April 12, 2023. DWR makes no warranties or guarantees —either expressed or implied — as to the completeness, accuracy, or correctness of the data. DWR neither accepts nor assumes liability arising from or for any incorrect, incomplete, or misleading subject data. Comments, problems, improvements, updates, or suggestions should be forwarded to GIS@water.ca.gov.,
Spring 1961 water table of California's Central Valley (from Williamson and others, 1989)
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This digital dataset defines the spring 1961 water-table altitude for the California's Central Valley. It was used to initiate the water-level altitudes for the upper 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, 2009). 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).
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