From source to sink: the response and recovery of coastal catchment ecosystems to large perturbations.

PI: Dr. E. Farrell, NUIG,

Dr. M. Bourke, TCD,

Dr K. Lynch, NUIG,

Dr T. Henry, NUIG,

Dr T. Morley, NUIG,

Dr. J. Turner, UCD

Funding:

index

Project summary:

From December 2013 to February 2014 Ireland was impacted by a series of large storms – some of the largest on record. These storms caused substantial coastal erosion, particularly along the west and south coast in Counties Mayo, Galway, Clare, Kerry, Cork, Waterford and Wexford. Extreme high water levels from the coupling of storm surge and very high spring tides eroded many beaches and dunes on the coast.

Currently there is very little knowledge about the resilience and recovery rates of Irish beach-dune systems in the aftermath of the low frequency, high magnitude storm surge events. Based on predictions of future scenarios, the frequency of intense cyclones (storms) over the North Atlantic area in the vicinity of Ireland will increase by about 15% for the period 2021-2060 compared with the current climate (EPA, 2005). There has also been an increase of about five percent in the long-term average annual rainfall for Ireland (comparing 1961-1990 against 1981-2010) (Walsh, 2012). Coupled with even modest sea level rises likely to occur in the coming decades the risk of coastal zone flooding is increasing.

Therefore, documenting the geomorphological and ecological effects of major storms is critical to assess the resilience of our unique coastal dune ecosystems – especially as they are a valuable defence against flooding and function naturally as a control on coastal erosion. Direct utilization of coastal dunes and beaches form an important economic role in many rural and urban coastal communities, rendering them key physical components in the socio-economic fabric.

Ecosystem services provided by beach-dune systems include recreational and tourism benefits, carbon sequestration, and habitat “functions” such as water purification, erosion control and habitat provision (Barbier et al., 2001). These are unique environments and, in many cases, are designated as Special Areas of Conservation (SAC) under the European Union (Natural Habitats) Regulations, 1997 and Natural Heritage Areas (NHA), designated under the Wildlife (amendment) Act 2000. Special attention must be paid to the needs of these areas where species are dependent on the water habitat resulting in receptor water bodies been designated as more sensitive to pressures.

Work Package 3 Dr Bourke:

 The coastal dune system is an inherently dynamic geomorphological landform that has high sensitivity to water fluxes (groundwater and near surface flow) through the system and climate shifts. Landform instability is a natural phenomenon in any dune field’s evolution. This instability is inherently linked to the ecology helping to construct species diversity. Jackson and Cooper (2011) have identified a rapid bio-geomorphic response on Irish coastal dunes as a result of recent climate change. The storms of 2013/2014 have perturbed the western coastal dune system causing erosion, destabilisation, and a fresh supply of sediment. The near surface water (vadose zone) of dunes influences species diversity. However, it is unknown how this vadose zone responds to significant erosion and depositional events. This poor understanding has limited our knowledge of the fundamental drivers of change in coastal dune field dynamics.

Objective 1 – Measure moisture flux changes in coastal dunes after sediment erosion and/or deposition.

Objective 2 – Determine how emplacement (rates and volumes) of moisture from precipitation events impacts dunes.

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