WELL LOCATION INFLUENCE ON SEAWATER INTRUSION IN COASTAL AQUIFERS

Coastal aquifers serve as an important freshwater resource for millions, but the increased groundwater extraction has exacerbated the risk of seawater intrusion (SWI). By understanding the influence of well pumping on SWI, we can better identify vulnerable aquifers and suggest water management policies to prevent contamination. Using 2-D SEAWAT groundwater flow and salt transport numerical models, we assess the extent of SWI in various aquifer characteristics (e.g. hydraulic conductivity, confining characteristics, recharge, etc.) and pumping schemes. Findings suggest that wells with deeper screened intervals located closer to the coast are most vulnerable to contamination, however well distance from the coastline matters more than well depth. If a system is not limited by recharge and the inland freshwater is at a constant head, the location of the pumping well is significant. This corresponds to topography-limited systems (i.e. aquifers in which the hydraulic heads are limited by topography rather than recharge). In addition to predicting which hydrogeologic conditions and well locations matter, we identify numerical model characteristics that may help water managers assess which existing well networks may be at the highest risk of contamination or determine future optimal pumping schemes.