Flooding project commenced by Geological Survey of Ireland

The Geological Survey of Ireland (GSI) has commenced a three year project on groundwater flooding related to turloughs. The project will see turloughs in Counties Roscommon, Galway and Longford studied in unprecedented detail.

The project will both provide an advisory service and also collect valuable flood data from high priority groundwater flooding sites in the Shannon Catchment and Gort lowlands. The GSI's collaboration with local authorities and the Office of Public Works (OPW) will help to effectively understand the subsurface role in flood risk zones and assess potential solutions.

Groundwater flooding is an issue of significant importance with two record-breaking flood events occurring since 2009. Unlike river or coastal flooding, where the floods are concentrated along a river or coastline, groundwater flooding is more widespread and is controlled by regional and local geology. Groundwater flooding predominantly occurs in the karstified limestone of West and North-West of Ireland and has historically been most severe in the Gort lowlands in Co. Galway. Rural areas are predominantly impacted by floods, which are typically linked with seasonal lakes known as turloughs. Excessive flooding in turloughs rarely poses a risk to life but does cause damage to properties and prolonged disruption due to the relatively long flood duration. At present, a number of turloughs in Counties Roscommon and Longford are still severely inundated due to the high rainfall from November and December 2015.

Turloughs are complex subsurface systems, and each one behaves differently. It is therefore crucial to develop a better understanding of their flooding patterns so that they can be managed more effectively.

Approximately 20 vulnerable sites will have fixed telemetric water level monitoring stations installed. Data from these stations will be assessed to monitor, understand and delineate groundwater flooding in Ireland.  Aerial surveys such as LIDAR and UAV imagery will also be utilised to improve current groundwater flood mapping in hazard zones. Furthermore, satellite remote sensing data will used to provide up-to-date flood mapping for unmonitored turlough systems.

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