ABSTRACT

Lafayette Parish uses 35.7 Mgal/d of groundwater that comes primarily from the Chicot Aquifer. In the Lafayette area the Chicot Aquifer consists of approximately 270 meters (800 feet) of Late Pleistocene arenaceous deposits. A major clay bed approximately 30 meters (100 feet) thick divides the aquifer into two informal units: an "Upper Sand Unit" and a "Lower Sand Unit".

This hydrogeological study integrates information from over 40 petroleum well logs, 40 municipal water well logs, several private wells, and several sand-analysis reports to produce a detailed top-of-sand map for both sand units in Lafayette Parish. These were input with key well logs and modeled with the Stratamodel 3D program to generate three dimensional pictures of resistivity that are called geobodies. These geobodies are an indication of the highest flow locations in the aquifer.

These three dimensional geobodies are significant in identifying possible water-well sites for local municipalities as well as in mapping ancestral deposition patterns. The top of sand map for the "Upper Sand Unit" is also significant in locating areas in the parish where the aquifer is closest to the surface and more rapid vertical migration is possible. This could be important for managing land use or the siting of future water resource projects and solid waste disposal facilities.