State Water Resources Research Institute Program (WRRI)

Details for Project ID 2008LA57B, 2008

Electrical Resistivity Tomography (ERT) Laboratory Experiments on Saltwater Encroachment Tracking and Modeling in Saturated Heterogeneous Sediment

Institute: Louisiana
Start Date: 2008-03-01 End Date: 2009-02-28
Total Federal Funds: $16,500 Total Non-Federal Funds: $33,002

Principal Investigators: Frank Tsai

Abstract: Rapid population growth and economic development in southeastern Louisiana have led to increased ground water demand. The largest ground water withdrawals have occurred in the East Baton Rouge (EBR) Parish and have induced the movement of saltwater across the Baton Rouge fault into many freshwater aquifers. Moreover, the EBR population has been almost doubled since Hurricane Katrina; and the Southern Louisiana has been suffered from the extreme drought since October 2005. EBR is facing a water demand challenge while experiencing the drought. Although ground water is anticipated to be one of the quick solutions for gaining additional water supply, excessive ground water withdrawal in the Capital Area will deteriorate the existing saltwater encroachment problem. Although ground water management plan is urgently needed for managing the Capital Area water resources, a utilitarian management plan relies on the fundamental understanding of the saltwater encroachment and a functioning tool to predict saltwater encroachment in the coastal aquifers. In other words, Louisiana coastal water resources would directly benefit through the better understanding of the saltwater encroachment processes in the subsurface and the development of a prediction model to be incorporated into a decision making system. The project proposes a systematic approach to better understand the saltwater encroachment in the coastal aquifer. The objectives include (1) saltwater encroachment experiments in a lab-scale sediment physical model; (2) electrical resistivity tomography (ERT) for saline plume characterization; and (3) numerical simulation to predict the saltwater encroachment. A number of significant parameters (e.g., dissolved salt dispersivity and hydraulic conductivity) in ground water flow and saltwater transport equations will be characterized and estimated through the ERT experiments and the inverse method. The research tasks include (1) electrical resistance/voltage measuring; (2) electrical potential modeling and ERT inversion; (3) saltwater encroachment modeling; (4) model calibration; and (5) model uncertainty analysis. The project outcomes will better understand saltwater encroachment mechanism and better the management model development. The ERT model will also serve as an educational and research tool to promote the understanding of saltwater encroachment in sediment to the undergraduate and graduate students.