THE EFFECT OF FAULTS UPON GROUND-WATER FLOW IN THE BATON ROUGE FAULT SYSTEM, LOUISIANA

The Baton Rouge Fault (BRF) is a growth fault that traverses Baton Rouge Parish. This fault is a part of the Baton Rouge Fault System (BRFS), located in South Louisiana. There are ten aquifers in the Baton Rouge area, which are the main source of freshwater. Beds dip and thicken southward toward the Gulf of Mexico. Aquifers in the Baton Rouge area are disrupted by the BRF. Aquifers contain fresh water in the updip (north of the BRF) and saline water in the downdip (south of the BRF) directions.

Saline water has intruded into some of the aquifers north of the BRF as a result of overpumping. It was assumed until recently that the BRF is acting as a leaky barrier for the movement of saline water north of the fault. In 2002 two studies asserted that this fault is acting as a conduit for saline water to migrate upward from deeper sources. The main purpose of this study was to analyze this controversy by review of previous literature, modeling, and geochemical analysis. The USGS model MOCDENSE was used to simulate density-driven two-dimensional flow. Five different scenarios were developed to explore the alternative explanations of movement of saline water. Available USGS geochemical and hydrological data plus geochemical data collected by Stoessell were used to calibrate the model. Modeling indicates that the fault can act as either a leaky barrier or a conduit for saline water to migrate north of the fault. Geochemical data also indicates that a dual role is likely.