Aquifer framework datasets used to represent the Kingshill aquifer, Island of St. Croix

The Kingshill aquifer resides under St. Croix, an Island in the U.S. Virgin Islands. The Island of St. Croix is mountainous in the northwestern and eastern regions of the island and the central and southwest regions contain rolling hills and plains. The Kingshill aquifer underlies the plains of St. Croix. The aquifer is composed primarily of limestone and marl and has a maximum saturated thickness of 200 feet. The aquifer doesn't produce large quantities of water and much of the groundwater is suboptimal for human consumption, but it is the primary source of water in the Virgin Islands (HA 730-N).    
 
This product provides source data for the U.S. Virgin Islands, Island of St. Croix, Kingshill aquifer framework including:
Georeferenced image: 
1. i_56KNGSHL_bot.tif: Digitized figure of altitude contour lines representing the bottom of the Kingshill aquifer. This figure also includes the Kingshill aquifer extent. The original figure was from the Groundwater Atlas (HA 730-N) figure 114. 
 
Extent shapefiles: 
1. p_56KNGSHL.shp: Polygon shapefile containing the areal extent of the Kingshill aquifer (HA 730-N). The original figure was from the Groundwater Atlas (HA 730-N) figure 114.
 
Contour line shapefile: 
1. c_56KNGSHL_bot.shp: Contour line dataset containing altitude values, in feet reference to National Geodetic Vertical Datum of 1929 (NGVD29), across the bottom of the Kingshill aquifer. These data were sourced from HA 730-N and were used to create the ra_56KNGSHL_bot.tif raster dataset.
 
Altitude raster files: 
1. ra_56KNGSHL_top.tif: Altitude raster dataset of the top of the Kingshill aquifer. Top of aquifer was assumed to be equal with land surface, but it should be noted that HA 730-N indicates about 25 percent of aquifer is overlain with a blanket of alluvium, alluvial fan, debris flow, and slope wash deposits as much as 80 feet thick. This raster was created using the Digital Elevation model (DEM) dataset (NED, 100-meter) and the altitude values are in meters reference to North American Vertical Datum of 1988 (NAVD88).
2. ra_56KNGSHL_bot.tif: Altitude raster dataset of the bottom of the Kingshill aquifer. This raster was interpolated from the c_56KNGSHL_bot.shp file and the altitude values are in meters reference to NAVD88.
 
Depth raster files: 
1. rd_56KNGSHL_top.tif: Depth raster dataset of the top of the Kingshill aquifer. The depth values are in meters below land surface (NED, 100-meter). All values in this raster are “0” because it was assumed the top of the aquifer was equal with land surface, but it should be noted that HA 730-N indicates about 25 percent of aquifer is overlain with a blanket of alluvium, alluvial fan, debris flow, and slope wash deposits as much as 80 feet thick.
2. rd_56KNGSHL_bot.tif: Depth raster dataset of the bottom of the Kingshill aquifer. The depth values are in meters below land surface (NED, 100-meter).