10.2.6 Flooding

opendate_range22 Dec, 2020, 9:00am - 12 Mar, 2021, 5:00pm
10.2.6 Flooding

Flooding is a natural phenomenon of the hydrological cycle.  There are many factors that influence flood behaviour and the degrees of risk that it possesses.  Like other natural processes, flooding cannot be completely eliminated, but its impacts can be minimised with proactive and environmentally sustainable management. The accepted national policy response to flood protection is now to manage the risk to life and property as sustainably as possible and to consider flood risk and its related impacts on development on a catchment basis, rather than on an individual location basis.  This will facilitate sustainable development through the reduction of future flood damage, and hence reduce the associated potential economic and social costs.

The Office of Public Works (OPW) is the lead agency for flood risk management in Ireland. The Planning System and Flood Risk Management – Guidelines for Planning Authorities were published in 2009 and these are incorporated here. 

The Guidelines outline three key principles that should be adopted by regional authorities, local authorities, developers and their agents when considering flood risk. These are:

  • Avoid the risk, where possible,
  • Substitute less vulnerable uses, where avoidance is not possible, and
  • Mitigate and manage the risk, where avoidance and substitution are not possible

Avoidance of development in flood risk areas

Flood zones are geographical areas within which the likelihood of flooding is in a particular range and they are a key tool in flood risk management within the planning process as well as in flood warning and emergency planning. There are three types or levels of flood zones defined for the purposes of the guidelines:

  • Flood zone A – where the probability of flooding is highest (greater than 1% or 1 in 100 for river flooding or 0.5% or 1 in 200 for coastal flooding) and where a wide range of receptors would be vulnerable;
  • Flood zone B – where the probability of flooding is moderate (between 0.1% or 1 in 1000 and 1% or 1 in 100 for river flooding and between 0.1% or 1 in 1000 year and 0.5% or 1 in 200 for coastal flooding); and
  • Flood zone C – where the probability of flooding is low (less than 0.1% or 1 in 1000 for both river and coastal flooding).

A Strategic Flood Risk Assessment has been carried out for the County as part of the Strategic Environmental Assessment.


​​​​​​​​​​​​​​ Flood Management:

It is Council policy to adopt a comprehensive risk-based planning approach to flood management to prevent or minimise future flood risk. In accordance with the Planning System and Flood Risk Management – Guidelines for Planning Authorities, the avoidance of development in areas where flood risk has been identified shall be the primary response. Development Management Requirements
  • Any area within or adjoining a flood zone, or flood risk area, shall be the subject of a site-specific Flood Risk Assessment appropriate to the type and scale of the development being proposed.  This shall be undertaken in accordance with the Flood Risk Assessment Guidelines.
  • If a Site Specific FRA demonstrates an unmanageable level of flood risk and/or impacts to 3rd party lands, development cannot proceed. 
  • Proposals for mitigation and management of flood risk will only be considered where avoidance is not possible and where development can be clearly justified with the Guidelines’ Justification Test.