Characterizing the Hydrogeology of Bell Harbour Catchment, a Coastal Karstic Aquifer Influenced by the Tide and Affected by a Saltwater Intrusion

A hydrogeological study focused on a karstic aquifer of a small catchment (~50 km²) located on the south coast of Galway Bay is described. The key aim of the study is to better understand the freshwater/seawater interaction in this coastal region west of Ireland. Discharge from the catchment is entirely through intertidal diffuse springs and submarine groundwater discharges (SGD). Logging of temperature, conductivity and water levels at coastal springs, turloughs and boreholes in the catchment is underway; water samples have been recovered for chemical analysis and water tracing has been undertaken. Initial results clearly show a tidal influence up to 2.5 km inland and an intrusion of seawater at least up to 1 km inland. This saltwater intrusion varies, depending on the balance between the tidal periods (spring/neap) and the groundwater level.