Thickness of the Chicot aquifer system of southwestern Louisiana’s surficial confining unit and shallow sand lenses

The Chicot aquifer system is a vital water resource for Southwestern Louisiana, providing nearly half of the fresh groundwater the region consumes (Sargent, 2011). The aquifer’s surficial confining unit (scu) consists of a wedge-shaped thickening sequence of south to southeastern dipping, interbedded clays and courser material (primarily sand and gravel). In collaboration with the Louisiana Department of Transportation and Development (LDOTD), Sargent and others (2004) extracted data from driller’s logs, geophysical logs, and well construction information for 2094 wells overlying the Chicot aquifer to enhance the delineation of the thickness and occurrence of the aquifer’s surficial confining unit. These data were applied here to create tabular data and a shapefile of discrete points that contain thickness data of the confining unit and tops and bottoms of sand and clay layers within the confining unit. A better understanding of the thickness and extent of the Chicot aquifer’s surficial confining unit will provide a framework for future aquifer characterization and will enhance the understanding of groundwater accessibility and availability for the southeast region. 1. Sargent, B.P., Frederick, C.P., Roberts, F.C., 2004, Thickness data for the Chicot aquifer system surficial confining unit: Louisiana Department of Transportation and Development Water Resources Basic Records Report no. 22, 91 p. 2. Sargent, B.P., 2011, Water use in Louisiana, 2010: Louisiana Department of Transportation and Development Water Resources Special Report no. 17, 135 p.