Fingal East Meath Flood Risk Assessment and Management Study

Study background

The FEM FRAMS is one of many studies being carried out to meet the requirements of the EU Floods Directive which was introduced on the 26 November 2007. The study will focus on urban areas known to have experienced flooding in the past and areas subject to significant development pressure both now and in the future.

Work on the study started in May 2008 and will continue until mid 2010 when a Flood Risk Management Plan (FRMP) will be published. This plan will define the levels of existing and future flood risk in the Fingal-East Meath area and set out how this will be managed both now and into the future.

Flood Risk in the Fingal East Meath Area

Fingal and Meath have suffered significant flooding over the last 12 years: August 1986 (Hurricane Charlie), November 2000 and November 2002 all resulted in considerable flood damage in the area. The highest recorded tidal levels in Dublin Bay occurred in February 2002, resulting in tidal damage to properties along the Fingal and Meath coast.

Fingal and Meath’s populations are rising rapidly, with an increase of over a fifth for both counties between 2002 and 2006. Fingal is now considered Ireland’s fastest growing area. Significant pressure now exists throughout Fingal and East Meath to develop marginal land.

The Fingal and East Meath region differs from other catchments in Ireland. Despite a low annual rainfall, small catchment areas and catchment slope, the region is highly susceptible to extreme flood events, as particularly demonstrated in the recent years. Our previous studies have indicated that major flood events in Fingal are often preceded by very wet periods (as occurred in November 2002), resulting in exceptional runoff. Radar plots at Dublin Airport also suggest that some extreme storms can stall over the south western catchments in the region resulting in intense prolonged rainfall.

Flood risk can also be increased by local conditions. These include bridges and culverts restricting high flows, debris causing blockages and environmental and land use changes. A table of the most significant recent flooding in the catchment is shown below. For more information on each of these flood events please visit the OPW's National Flood Hazard Mapping website.

Flood event	Main flood mechanism	Rivers affected	Areas affected
November 1982	Fluvial	Ward River, Broadmeadow River	Swords Area
August 1986	Fluvial	Broadmeadow River, Ward River, Mill Stream	Swords, Skerries, Balbriggan, Duleek,
June 1993	Fluvial	Mayne River, Nanny River	Balgriffen, Duleek
October 1993	Fluvial	Nanny River	Duleek
February 2002	Tidal	Ward River, Mayne river, Turvey River, Sluice river	Swords, Portmarnock, Maynetown, Skerries, Portrane
October 2002	Fluvial	Ward River, Sluice River	Portmarnock, Swords Area
November 2002	Fluvial	Broadmeadow River, Ward River, Rush Town Stream	Balbriggan, Swords Area, Rush

Study area

The study area of the project is indicated in the table below. This area constitutes the Irish Hydrometric Area 8 and some of Area 9, as defined by the Environmental Protection Agency (EPA) and is approximately 771.69 sq km in plan area.

Mayne River
Sluice River
Gaybrook Stream
Broadmeadow River
Ward River
Lissenhall Stream
Turvey River

Ballyboghil River
Corduff River
Nanny River
Balleally Stream
Bride’s Stream
Jone’s Stream
Rush Town Stream

St Catherine’s Stream
Mill Stream
The Bracken River
Delvin Stream
Mosney Stream

The main urban areas within the study catchment are listed below.

Bettystown
Laytown
Balbriggan
Rush
Ratoath
Duleek

Lusk
Portrane
Skerries
Dublin Airport
Dunshaughlin
Stamullen

Portmarnock
Donabate
Swords
Ashbourne

In addition to the above there are a number of urban clusters/villages including Naul, Ballyboghil, Carristown and Oldtown.

Objectives

The objectives of the FEM FRAMS are to:

Identify and map the existing and potential future flood hazard and risk areas within the study area.
Build the strategic information base necessary for making informed decisions in relation to managing flood risk
Identify viable structural and non-structural measures and options for managing the flood risks for localised high-risk areas and within the catchment as a whole.
Prepare a Flood Risk Management Plan for the study area, and associating Strategic Environmental Assessment, that sets out the measures and policies, including guidance on appropriate future development, that should be pursued by the local authorities, the OPW and other stakeholders to achieve the most cost effective and sustainable management of flood risk within the study area taking account of the effects of climate change and complying with the requirements of the Water Framework Directive.

The flood hazards and risks to be addressed include both those that currently exist and those that might potentially (foreseeably) arise in the future. The risk management measures, options and management plan should equally address both existing and potential future hazards and risks.

The Flood Risk Management Plan will include prioritized studies, actions and works (structural and non-structural), including indicative costs and benefits, to manage the flood risk in the area in the long-term, and make recommendations in relation to appropriate development planning. The project is intended to develop a strategic flood risk management plan, and is not intended to develop detailed design of individual risk management measures.