nuig biogeoscience research group

karst groundwater study

Background

• Coastal regions in western parts of Ireland (Counties Galway and Clare) are characterized by vulnerable karst aquifer systems.

• A karst aquifer is a type of bedrock aquifer that is composed of soluble rock (e.g., limestone).

• Fast flowing groundwater in karst aquifers is usually concentrated within conduits.

• Conduits in karst aquifers are often much larger than the pore spaces that are present in sand/gravel aquifers.  As a result, groundwater flow rates in karst aquifers are much faster (up to km/day) than groundwater flow rates in sand/gravel aquifers (m/day).
  

• The presence of conduits in coastal karst aquifers has several consequences:
  • contamination of groundwater and seawater can occur easily and spread widely;
  • there may be little or no natural attenuation of contaminants in the system;
  • the ingress of saltwater may occur easily; and
  • large amounts of potentially usable freshwater supplies may be lost to the sea.

• Climate change impacts may have a significant impact on water quality in coastal karst systems:
  • sea-level rise could result in an increase in the extent of saltwater ingress in coastal zones, possibly reducing the availability of potable water supplies;
  • increased flooding frequency could result in a greater groundwater contamination risk, and possibly affect marine water quality at groundwater discharge points.

project goals

• The aim of this study is to provide a good understanding of the hydrogeology and biogeochemistry of coastal karst aquifer systems.

• In order to achieve this objective, the following aspects of the karst systems located in Co. Galway and Co. Clare will be studied in detail:
  • groundwater chemistry;
  • biogeochemical reactions;
  • groundwater flow paths, discharge, and residence times;
  • nutrient and contaminant loading;
• saltwater intrusion.

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