Groundwater flood risk mapping and management: examples from a lowland karst catchment in Ireland.

The complexity of groundwater flooding poses unique challenges to policy makers and flood risk management agencies. An understanding of the interactions among recharge, storage and transport mechanisms during flood conditions is a precursor to effective groundwater flood risk assessment, but is often absent due to a lack of adequate data. The example of the Gort Lowlands, a major lowland karst catchment in the Republic of Ireland, is used to elucidate key flood mechanisms which must be considered when characterising groundwater flood risk in a lowland karst setting. The combination of large quantities of allogenic recharge, a high-capacity conduit system and deep surface depressions renders the catchment susceptible to groundwater flooding. Observed flood mechanisms include backwater flooding of sinks, overland flow caused by the overtopping of sink depressions, high water levels in turlough basins and surface ponding in local epikarst watersheds. Flood hazard maps are developed for the region using data collected during a major flood event in the winter of 2009, representing a significant contribution in the assessment and management of groundwater flood risk in Ireland. Major challenges to groundwater flood management and forecasting remain, however, and are discussed in the context of the prevailing hydrogeological and ecohydrological setting. [ABSTRACT FROM AUTHOR]