Semester of Graduation

Summer 2024

Degree

Master of Science in Civil Engineering (MSCE)

Department

Department of Civil and Environmental Engineering

Document Type

Thesis

Abstract

The Sparta-Memphis aquifer is one of the major sources of domestic and industrial water supplies in the Mississippi Embayment region. However, besides altering the natural direction of flow, several serious complications such as elevated chloride concentration, significant water level decline, large cones of depression, and land subsidence have arisen from excessive groundwater consumption. To better understand the Sparta-Memphis aquifer condition, a high-resolution groundwater flow model for the Sparta-Memphis aquifer was developed in this study to assess groundwater availability and analyze aquifer responses to future groundwater withdrawal scenarios. For the development of the groundwater flow model, firstly about 3,700 electrical log data was interpreted. Secondly, monthly groundwater usage data from 1995 to 2020 has been compiled from 5 states. Thirdly, a MODFLOW 6 groundwater flow model was developed utilizing the unstructured grid approach and finally, the model was calibrated using the trial-and-error method. The simulation from January 2004 to December 2020 showed an improvement in the minimum groundwater head from -227.73 meters to -115.33 meters due to the reduction of groundwater withdrawal by Arkansas and Tennessee after 2015. The zone budget analysis reveals that the Sparta-Memphis aquifer constantly loses groundwater to the nearby streams. The contribution of the surficial recharge was found to be very small, however, the Middle Claiborne Confining Unit was found to be the largest inflow source of the aquifer. An analysis of five hypothetical withdrawal scenarios has revealed that a 50% or less reduction in withdrawal from Union County, Jefferson County, and Ouachita Parish does not result in a significant recovery in the hydraulic head, however, such reduction is effective in Shelby County. The improvement in the potentiometric surface of Union County, Jefferson County, and Ouachita Parish can be achieved by shutting down some of the high-producing industrial wells.

Date

7-5-2024

Committee Chair

Tsai, Frank

DOI

https://doi.org/10.31390/gradschool_theses.5997

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