VULNERABILITY OF COASTAL AQUIFERS TO SALINIZATION BY SEAWATER: INFLUENCE OF SEA-LEVEL RISE, STORM SURGES, AND GEOLOGIC STRUCTURE

In the coming decades, changes in sea level, precipitation, and temperature are likely to impact groundwater resources, particularly in coastal areas where salinization by seawater already threatens aquifer systems. Understanding the primary factors that affect aquifer vulnerability to changes in salinity and submarine groundwater discharge and determine the magnitude of system response are critical to developing effective management plans in coastal zones. We use a variety of methods to model variable-density groundwater flow and solute transport in coastal zones to evaluate mechanisms of salinization, including lateral (classical) seawater intrusion, vertical infiltration from surface floods, and impacts of pumping. We also use geostatistical modeling methods to explore the influence of geologic structure on salinity distributions, aquifer vulnerability, and submarine groundwater discharge. We consider in particular the case of the Bengal Delta, one of the most vulnerable regions in the world to sea-level rise due to its low topographic elevation and dense population, and we generalize this to include other types of hydrogeologic systems.