Digital data for 3-D Geologic Framework and Textural Models for Cuyama Valley Groundwater Basin, California

This digital dataset was created as part of a U.S. Geological Survey study in cooperation with the Santa Barbara County Water Agency to conduct a hydrologic resource assessment and develop an integrated numerical hydrologic model of the hydrologic system of Cuyama Valley, CA. As part of this larger study, the USGS developed this digital dataset of geologic data and three-dimensional hydrogeologic framework models, referred to here as the Cuyama Valley 3-D hydrogeologic framework models (3DHFM), that define the elevation, thickness, extent, and lithology-based texture variations of three hydrogeologic units in the Cuyama Valley, CA, groundwater basin. A USGS report that described the construction of 3-D geologic framework and textural models for Cuyama Valley groundwater basin was published in 2013 (Sweetkind and others, 2013). This data release formalizes the input geologic data and model outputs as a digital dataset. The Cuyama Valley 3DHFM incorporates as input data stratigraphic and lithologic information derived from water, monitoring, and oil and gas wells, as well as data from geologic maps and interpreted structure contour maps. Input surface and subsurface data have been reduced to points that define the top elevation and textural or grain-size characteristics of each hydrogeologic units at x,y locations; these point data sets serve as digital input to the framework models. The location of wells used sources of subsurface stratigraphic and lithologic information are provided as separate point feature classes in a geospatial database. Faults that offset hydrogeologic units are provided as a separate line feature class. Borehole data are also provided in a Microsoft Excel spreadsheet that includes separate TABs for well location, stratigraphic information of the depths to top and base of hydrogeologic units intercepted downhole. Two types of geologic frameworks were constructed: (1) a hydrostratigraphic framework where the elevation, thickness, and spatial extent of the three basin-fill hydrogeologic units were defined based on interpolation of the input data, and (2) a textural model for each hydrogeologic unit based on kriging-based interpolation of classed downhole lithologic data. Each of the frameworks is stored within a second geospatial database as an array of polygonal cells or cell centroids: essentially a “flattened”, two-dimensional representation of a digital 3D geologic framework. The elevation and thickness of the hydrogeologic units are contained within a point feature class which contains a mesh of cell centroids that represent model cells that have multiple attributes including x,y location, elevation, and thickness of each hydrogeologic unit. Computed textural information for each of the three basin-fill hydrogeologic units are stored in separate feature classes of polygonal cells where a single textural variable “percent coarse grained” is an attribute at each x,y location. The spatial data are accompanied by non-spatial tables that describe the sources of geologic information, a glossary of terms, a description of model units, and a Data Dictionary that duplicates the Entity and Attribute information contained in the metadata file. Spatial data are also presented as shapefiles and borehole data are provided in Microsoft Excel spreadsheet. The elevation, thickness, and textural model of each hydrogeologic unit are also released as raster files.