Saltwater intrusion in coastal aquifers subjected to freshwater pumping

Abstract

Investigations are carried out to analyze the effect of freshwater pumping on saltwater intrusion in coastal aquifers in the presence of a semipervious subsurface barrier along the coast. A conceptual, unconfined aquifer with a subsurface barrier subjected to simultaneous freshwater pumping at single/multiple locations perpendicular to the coast is considered for the analysis. The location, width, and the conductivity of the subsurface barrier being held constant, the effect of freshwater pumping at seaward and landward locations from the barrier is investigated on the interface motion. The performance of the barrier is compared with a nonbarrier condition. The numerical model developed predicts the behavior of the saltwater-freshwater interface and the piezometric surface due to simultaneous pumping at single/multiple wells across the sea cost. The barrier is effective in checking the progress of saltwater for freshwater pumping on the landward side of the barrier compared to no barrier condition. The freshwater pumping on the seaward side of the barrier should be limited to smaller rates. Additionally, safer zones for simultaneous freshwater withdrawal are identified for single, two, three, and four wells without the advancement of saltwater intrusion. The results obtained are of general nature and would be useful in determining the ideal location and rate of freshwater withdrawal minimizing the saltwater intrusion in coastal aquifers. © 2014 American Society of Civil Engineers.