Sustainable management of two‐directional lateral and upconing saltwater intrusion in coastline aquifers to alleviate water scarcity

Abstract

AbstractLateral saltwater intrusion (LSWI) and vertical saltwater intrusion (VSWI) are the major problems in coastal aquifers. Coastal aquifers are subjected to natural and artificial changes, including sea‐level rise, decreasing inland recharge, and overexploitation of production wells' water resources. Therefore, this study investigates the influence of changing the coastal aquifers boundary conditions considering climate changes' effect. Parameters describing the upward saline well parameters based on the abstraction conditions, also, the top layer properties were studied based on the erosion and sediments, irrigation, and drainage conditions. For this purpose, the SEAWAT model was employed to simulate lateral SWI based on Henry's problem principle. The sensitivity analysis of the mentioned parameters was accomplished considering as a case study the Biscayne aquifer in the Cutler Ridge area near Deering Estate, Florida, USA, where the LSWI and VSWI were also investigated. The results indicate that the boundary conditions, abstraction well parameters, and top layer cost significantly impact aquifer LSWI and water upconing. The simulation results of the Biscayne aquifer for a saline water head of 84.86 cm for 2060 indicate a decrease in freshwater recharge by 30% and increasing the saltwater concentration by 14.30%. At the same time, the LSWI increased by 3.30%, 22.80%, and 8.70%, while the relative upconing heights reached 0.63, 0.60, and 0.47 compared with 0.42 for the current situation. Increasing the upward saline abstraction well discharge rates by 50% increases the LSWI by 9.40%. In contrast, increasing the depth by 10%; decreases the distance by 30%, the screen length by 30%, the LSWI decreased by 1.80%, 25.10%, and 1.30%, respectively. At the same time, the relative VSWI height reached 0.60, 0.39, 0.48, and 0.40, respectively. Moreover, decreasing the top layer hydraulic conductivity by 25% and increasing the aquitards layer depths by 200% decreased the LSWI by 4.90% and 7.80%, respectively. At the same time, the relative VSWI height reached 0.34 and 0.30, respectively. In addition, the saline water heads, a freshwater recharge should be controlled to manage SWI; the upward well should be utilized at a low abstraction rate, far from the seaside, and with minimum screen length. The agriculture activity for decreasing the soil permeability for the top layer must be extended for better management of the SWI. The solution‐oriented findings resulting from this study might be useful for decision‐makers and engineers to develop effective management measures to tackle the SWI issue in coastal aquifers.