Salinization Simulation for the “1,200-1,500-1,700-foot” Sands of the Baton Rouge Area, Southeastern Louisiana

Nima Chitsazan, Jeffrey Hanor, Hai Pham, and Frank Tsai
[email protected]

Groundwater resources are vital for Louisiana's economic and demographic developments. Many freshwater aquifers underneath Baton Rouge are being contaminated by saltwater intrusion due to excessive groundwater withdrawals. This study developed a SEAWAT model to simulate salinization in the '1,200-foot' sand, the '1,500-foot' sand and the '1,700-foot' sand in the Baton Rouge area. A geological architecture was reconstructed by well log data, and then converted into a MODFLOW computational grid. The SEAWAT model was calibrated using 2805 groundwater head data and chloride data from 1975 to 2010 from 21 USGS observation wells. The initial chloride concentration distribution was derived from USGS water quality database and from estimated salinity using spontaneous potential (SP) and deep electrical resistivity curves from 42 well logs in the area. We developed a parallel version of the Covariance Matrix Adaptation-Evolution Strategy (CMA-ES) for high performance computing (HPC) in supercomputers to calibrate the SEAWAT model and estimate model parameters. Based on the simulation result, the Baton Rouge (BR) fault and the Denham Springs-Scotlandville (DSS) fault were found to be low-permeability faults that restricted horizontal groundwater flow. The head difference was estimated 20 meters across the BR fault and 10.8 meters across the DSS fault in 2010 in the '1,200-foot' sand. The head difference was estimated 29.4 meters across the BR fault and 7.6 meters across the DSS fault in 2010 in the '1,500-1700-foot' sands. The SEAWAT model showed a distinct saltwater intrusion pattern moving northward from south of the Baton Rouge fault towards the Lula pumping station.

AAPG Search and Discovery Article #90167©2013 GCAGS and GCSSEPM 63^rd Annual Convention, New Orleans, Louisiana, October 6-8, 2013