Strategies for monitoring groundwater discharge into Kinvara Bay, Galway, Ireland

Submarine and intertidal groundwater discharge (SIGD) is of increasing global significance due to its role in transporting freshwater to the ocean as well as contaminants or nutrients. The increasing anthropogenic impacts on... [ view full abstract ]

Submarine and intertidal groundwater discharge (SIGD) is of increasing global significance due to its role in transporting freshwater to the ocean as well as contaminants or nutrients. The increasing anthropogenic impacts on the environment pose significant risks to the quality of aquatic systems, specifically in highly vulnerable karst systems. Past groundwater monitoring programs have classified the Western River Basin District and specifically the Kinvara-Gort groundwater body to be of high risk for contamination. This ground water body is primarily underlain by limestone that includes large fissures, cracks, and tunnels that act as preferential flow paths for groundwater. This project located the various SIGD occurrences in Kinvara Bay using a fusion of data collected via the Earth Observation satellite, small aircraft and in-situ sensors. Over the course of a four day field campaign in late August 2015, ~65,000 in-situ temperature and salinity measurements were collected in accordance with aircraft flyovers. The in-situ data was spatially interpolated with ArcGIS software and will be used to ground truth thermal infrared imagery. Processed in-situ data illustrate clear gradients in temperature and salinity at the southern end of Kinvara Bay where freshwater springs are identified at low tide. Salinity values near the southern end of the bay were found to be as low as 1-2 ppt opposed to 29-31 ppt on average closer to the mouth of the bay. This variance in salinity indicates the presence of a freshwater wedge that extends some distance outwards from the Kinvara Springs where it mixes with seawater.