The use of injection wells and a subsurface barrier in the prevention of seawater intrusion: a modelling approach

摘要

Damsarkho (Latakia, Syria) coastal aquifer is under severe hydrological stress due to the overexploitation of a shallow groundwater table for irrigation and tourism. Excessive pumping during the past few decades has caused a significant lowering of groundwater levels, which has in turn lead to seawater intrusion into the aquifer. Meteoric infiltration and flow from the adjoining carbonate aquifer recharges the Damsarkho aquifer. Natural outflow occurs through a diffuse flow into the sea, while artificial outflow occurs through intensive extraction of groundwater via wells. Water exchange in the aquifer takes place both naturally (leakage) and artificially (multi-screened wells). For the purpose of planning and management, SEAWAT, a variable density solute transport computer code, was used to study groundwater volume and quality. Seawater intrusion was represented by a three-dimensional finite difference model using the SEAWAT numerical code of VisualModflow software; the conceptual model is based on field and laboratory data collected between 1960 and 2003. Results obtained from the model establish that seawater intrusion is essentially due to withdrawal near the coast during the irrigation season, which occurs almost entirely in the Damsarkho plain. This simulation also demonstrates that the use of injection wells or a subsurface barrier would both represent a good method with which to improve water quality and prevent seawater intrusion.