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Flooding

Flooding

Flooding in Ireland can have a significant impact on property, people, communities, the environment and cultural heritage. It is likely that climate change will increase flood risk in Ireland due to rising sea levels, increased rainfall in winter, more heavy rain days and more intense storms.
 

Sources of Flooding

Flooding can occur from a range of sources, individually or combines

The Office of Public Works (OPW) is the lead organistion for flood risk management in Ireland and has the national authority for the implementation of the EU Directive on the Assessment and Management of Flood Risks 2007/60/EC.

Flood Policy Background

1945 Arterial Drainage Act (amended 1995)
The Arterial Drainage Act of 1945 provided for a national drainage plan that was focused on arterial drainage for the benefit of agricultural improvement. Arising from increasing flood risk in urban areas, the Act was amended in 1995 to permit the OPW to implement flood relief schemes to provide flood protection to cities, towns and villages.

Under the Act construction and alteration of watercourse, bridges, weirs and embankments require the prior consent of the OPW.
 
2004 Flood Risk Policy
A review of national flood policy was undertaken in 2003-2004 by an Interdepartmental Review Group. Their report included a review of the roles and responsibilities for managing flood risk and set out new policy for flood risk management in Ireland. The report was approved by Government and published in September 2004. Further details can be found here.
 
EU Flood Directive & SI No. 122 of 2010
The EU ‘Floods’ Directive looks to reduce the adverse consequences of flooding on human health, the environment, cultural heritage and economic activity. The Directive which came into force in 2007 requires Member States to undertake three key steps of analysis and planning:
 
  1. A Preliminary Flood Risk Assessment (FRA) based on available or readily-derivable information.
  2. The preparation of Flood Hazard and Risk Maps
  3. The preparation of Flood Risk Management Plans (FRMPs) setting out objectives and a set of measures aimed at the management and reduction of flood risk.
The flood maps and the FRMPs are available on www.floodinfo.ie.

The EU Floods Directive was transposed into Irish Law by the European Communities (Assessment and Management of Flood Risks) Regulations 2010, S.I. No. 122 of 2010 and amended by S.I. No. 495  of 2015.

Government’s National Flood Risk Policy

There are three strategic pillars to the Government’s National Flood Risk policy; Prevention, Protection, Preparedness.
 

Prevention

Flood risk prevention is aimed at averting flood risk, for example by avoiding construction in flood prone areas.
 
Planning System and Flood Risk Management Guidelines
Local Authorities are to regard the Planning System and Flood Risk Management guidelines issued under Section 28 of the Planning & Development Act 2000,  in their functions, such as preparing development plans and determining planning applications.
 

Protection

Protection measures are aimed at both structural and non-structural interventions to reduce the likelihood and/or impact of flood events in an area, such as defending areas at risk against flooding, diverting the peak flood flows or reducing flood levels.
 
Major Flood Relief Schemes
The OPW can work in association with the relevant local authority or funds local authorities directly to undertake major flood relief schemes throughout the country. 

OPW Flood Defence Schemes are generally carried out under the Arterial Drainage Act 1945 and the Arterial Drainage Amendment Act 1995, although in recent years some phases of schemes have been carried out by the Local Authorities under the Planning and Development Regulations.

Links to information on Flood Defence Schemes are available here.

Minor Works & Coastal Erosion
The OPW provides funding to local authorities through the  Minor Flood Mitigation Works and Coastal Protection Scheme to undertake minor flood mitigation works or studies to address localised flooding and coastal protection problems within their area.

The scheme generally applies where a solution can be readily identified and achieved in a short timeframe. Funding of up to 90% of the cost is available under the scheme for projects that are estimated to cost not more than €750,000 in each instance.

Details of the scheme and works approved are available here.
 
Arterial Drainage Schemes
Under the Arterial Draining Act 1945, the OPW have carried out a number of arterial drainage schemes to improve land for agriculture and to mitigate flooding.

The OPW is responsible for  approx. 11,500km of river channel, including approx. 800km of embankments of which most is tidal, and almost 20,000 structures, which form part of the Arterial Drainages Schemes completed since 1945.  The purpose of the scheme was to ensure that the 3-year flood was retained in bank.

The OPW Benefiting Lands maps show land which would (or have) benefited from an arterial drainage scheme. These maps are not based on a ‘design flood’ but  indicate low lying,  poorly drained land. 

Under section 37 of the 1945 Act, the OPW is required to maintain the drainage works in proper repair and in an effective condition through an annual maintenance programme. This work is organised on a regional basis, with regional offices in Mungret, Co. Limerick, Headford Co. Galway and Trim, Co. Meath.

A list of the major completed Arterial Drainage Schemes carried out by OPW can be found here. An online map of the country with detailed information on the location of OPW Arterial Schemes can also be found on www.floodinfo.ie.

Drainage Districts Schemes
Prior to the Arterial Drainage Act of 1945, District Drainage was carried out by the Commissioners of Public Works to improve land for agriculture and to mitigate flooding. When a 1945 scheme covered the same ground as one of an earlier scheme that Drainage District was abolished.

Local authorities are charged with responsibility to maintain Drainage Districts and have an obligation to make annual returns to the OPW stating the expenditure and summarising the work completed on all of the Districts.

The Arterial Drainage Act, 1945 contains a number of provisions for the management of Drainage Districts in Part III and Part VIII of the act.
 
Guidance to Landowners
The OPW published a guidance document in January 2020 aimed at owners of land or property which is located on banks of a watercourse, commonly termed, ‘riparian owners’.

The guidance outlines the rights and responsibilities of ripeiaran owners and provide practical advice on management of watercourse. A copy of the ‘Living Near Watercourse – A Guide to the Rights and Responsibilities of Landowners” can be downloaded here.
 

Preparedness

Actions and measures that can be taken to reduce the consequences of flooding to ensure that people and communities are prepared for flood events.
 
Weather Forecasting
Met √Čireann issue three categories of weather warnings ahead of severe weather; yellow, orange and red warning. Further information can be found here.
 
National Flood Forecast System
Following a Government decision in January 2016, Met √Čireann, in collaboration with the OPW, are a National Flood Forecasting and Warnings Service (NFFWS) to forecast for fluvial and coastal floods. It is expected to become operational in Q3-2021.

The CAROs have been involved in the Communications Steering Group for the system.

OPW Tidal & Storm Surge Forecasting
The national Tide and Storm Surge Forecasting Service operated by the OPW provides Local Authorities with up to three days advance warning of impending coastal surge events.
 
European Flood Awareness System (EFAS)
EFAS is a medium range (typically 3 to 10 days) operational flood forecasting system based on metrological forecasts from a number of European centres that provides complementary, added-value information to the relevant national and regional authorities. Further information can be found here.
 
Real-Time Water Level Data
The OPW, together with local authorities and Waterways Ireland own, operate and maintain the vast majority of surface water hydrometric gauges. The EPA maintains the Register of Hydrometric Stations in Ireland.

The data from surface water gauging stations at over 300 river, lake and tidal locations is available in real-time at www.waterlevel.ie. The website also hosts an archive of assessed water level and flow data presented in various commonly used formats including daily mean water level and flow data, water level and flow duration curves and annual maxima water level and flow series.
 
Emergency Planning
Under the Major Emergency Management Framework, local authorities are the lead agency for flood emergency response and disseminates flood warning to the other Principal Response Agencies and to the public as necessary. Further information can be found here.