Ministerial guidelines
The Planning System and Flood Risk Management: Guidelines for Planning Authorities
Flood Zones A, B and C, the sequential approach and the Justification Test for development in areas at risk of flooding.
Department of the Environment, Heritage and Local Government and the Office of Public Works · November 2009 · 81 pages
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- 53 Guidelines for Planning Authorities The Planning System and Flood Risk Management Fig. 5.1: Consideration of flood risk in the development management process Development Management Stage Consideration of Flood Risk Management 1. Pre-application 2. Lodgement 3. Processing 5. Appeals 4. Decision Notification Further revisions Grant Refuse Possible revisions, Further information, etc. 1. Proposer to gather relevant flood information (historic and predictive). Refer to Appendix A for sources. 2. Is application consistent with a development plan that has been prepared in accordance with these Guidelines? 3. Is a review of policy on flood risk in the development plan forthcoming? 4. Based on the above are there any issues of prematurity? (see paragraphs 5.19-5.27 for further information). 5. Consultation between LA and proposer to discuss application of Justification Test. Proposer to carry out appropriate FRA and/or EIA as required to support the application if the site is considered suitable for development (see paragraphs 5.15-5.18 for further information). 1. Any known flood history on a site to be declared and described in the planning application form as required by the Planning and Development Regulations 2006. 2. EIS or FRA to accompany application. 3. Application demonstrates use of Sequential Approach as appropriate. 1. Internal council consultation. 2. Prescribed bodies. 1. Further information or studies. 2. Amendments or additions to EIS and/or FRA. Grant with conditions: Sequential approach /Justification Test passed. Residual risks are acceptable following flood mitigation measures. Flood mitigation measures can be dealt with by reasonable conditions (e.g. appropriate use of SuDs). Refuse: Flood issues have not been, or cannot be addressed successfully with or without conditions. Residual risks are unacceptable. The application is inconsistent with development plan policies and objectives in relation to flood risk management. Proposal is premature prior to taking a review of flood risk in the current development plan (see paragraphs 5.19-5.27 for further information).
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- Under these Guidelines, regional authorities and planning authorities have a key role to play in ensuring that effective policy frameworks are put in place to require that new development is both located and provided in such a manner as to minimise the risk from flooding. Applicants for planning permission, their agents and developers also have a key role to play in working with the policy framework referred to above and in completing development in compliance with planning permissions granted. The Government is undertaking significant work to enhance the level of detail and coverage of flood maps and other information on flood risks, primarily through the preparation of flood risk management plans and to support the development of the policy framework referred to above. However, in advance of the preparation of these maps and plans for any particular area, it is to be expected that planning authorities should identify flood risk issues and, where necessary, undertake further stages of flood risk assessment at relevant stages of the planning and development management processes. Assessment of flood risk should inform the on-going revision of development plans and local area plans. Planning applications submitted after the publication of these Guidelines should be accompanied as appropriate by flood risk assessments, enabling their proper consideration by planning authorities and An Bord Pleanála with regard to flood risk, even though the relevant development plan or local area plan may not yet have been reviewed in the light of these Guidelines. Planning authorities must strike a fair balance between avoiding flood risk and facilitating necessary development, enabling future development to avoid areas of highest risk and ensuring that appropriate measures are taken to reduce flood risk to an acceptable level for those developments that have to take place, for reasons of proper planning and sustainable development, in areas at risk of flooding. The Minister will monitor the on-going implementation of these Guidelines to ensure that flood risk management is fully integrated into the planning process. 6.1 6.2 6.3 6.4 6.5 55 Conclusion Guidelines for Planning Authorities The Planning System and Flood Risk Management
- Glossary of Terms Terms Definition Breach of defences A structural failure at a flood defence allowing water to flow through. Catchment The area that is drained by a river or artificial drainage system. Catchment Flood Risk Assessment and Management Studies (CFRAMS) A catchment-based study involving an assessment of the risk of flooding in a catchment and the development of a strategy for managing that risk in order to reduce adverse effects on people, property and the environment. CFRAMS precede the preparation of Flood Risk Management Plans (see entry for FRMP). Climate change Long-term variations in global temperature and weather patterns, which occur both naturally and as a result of human activity, primarily through greenhouse gas emissions. Coastal erosion The gradual wearing away of the coastline through a combination of wave attack and, in the case of coastal cliffs, slope processes (e.g. high groundwater levels). This may include cliff instability, where coastal processes result in the periodic reactivation of landslide systems or promote rock falls. Coastal flooding Flooding from the sea which is caused by higher than normal sea levels and/or high waves resulting in the sea overflowing onto the land. Consequence of flooding Health, social, economic and environmental effects of flooding, some of which can be assessed in monetary terms, while other less tangible impacts are more difficult to quantify. Consequences depend on the hazards associated with the flooding and the vulnerability of receptors. Conveyance function When a river overflows its banks, it continues to flow over the flood plain, conveying water down-stream, as well as storing water where the flood plain may be obstructed and releasing it slowly. Core of an urban settlement The core area of a city, town or village which acts as a centre for a broad range of employment, retail, community, residential and transport functions. 56
- Detailed flood risk assessment A methodology to assess flood risk issues in sufficient detail and to provide a quantitative appraisal of flood hazard and potential risk to an existing or proposed development, of its potential impact on flood elsewhere and of the effectiveness of any proposed measures. Environmental Impact Assessment (EIA) Pursuant to EU Directive 85/ 337/ EEC (as amended in 1997), EIA is a legislative procedure used for identifying the environmental effects of development projects to be applied to the assessment of the environmental effects of certain public and private projects which are likely to have significant effects on the environment. Estuarial flooding Flooding from an estuary, where water level may be influenced by both river flows and tidal conditions, with the latter usually being dominant. Flash Flood A flash flood is a rapid flooding of an area of land as a result of intense or extreme rainfall events or failure of infrastructure designed to store or carry water or protect against flooding and is distinguished from general flooding by the sudden onset. Flooding (or inundation) Flooding is the overflowing of water onto land that is normally dry. It may be caused by overtopping or breach of banks or defences, inadequate or slow drainage of rainfall, underlying groundwater levels or blocked drains and sewers. It presents a risk only when people, human assets and ecosystems are present in the areas that flood. Flood Relief Schemes (FRS) A scheme designed to reduce the risk of flooding at a specific location. Flood defence A man-made structure (e.g. embankment, bund, sluice gate, reservoir or barrier) designed to prevent flooding of areas adjacent to the defence. Flood-detention reservoirs An embanked area designed to hold floodwater from areas upstream and release it slowly to reduce flooding downstream. Embankments may be constructed across the river or adjacent to the river, with flood flows being diverted into the reservoir area. Terms Definition 57 Guidelines for Planning Authorities The Planning System and Flood Risk Management
- Flooding from artificial drainage systems This occurs when flow entering a system, such as an urban storm water drainage system, exceeds its discharge capacity, becomes blocked or when the system cannot discharge due to a high water level in the receiving watercourse. Flood hazard The features of flooding which have harmful impacts on people, property or the environment (such as the depth of water, speed of flow, rate of onset, duration, water quality etc). Flood hazard assessment An assessment of the hazards that would arise from flooding, e.g. identifying where flooding would occur, how deep the water would be, how fast it would flow, how rapidly would it rise and how long it would remain. Floodplain A floodplain is any low-lying area of land next to a river or stream, which is susceptible to partial or complete inundation by water during a flood event. Flood risk An expression of the combination of the flood probability or likelihood and the magnitude of the potential consequences of the flood event. Flood risk assessment (FRA) FRA can be undertaken at any scale from the national down to the individual site and comprises 3 stages: Flood risk identification, initial flood risk assessment and detailed flood risk assessment. Flood risk identification A desk-based study to identify whether there may be any flooding or surface water management issues related to a plan area or proposed development site that may warrant further investigation. Flood Risk Management (FRM) FRM combines the function of mitigating and monitoring flood risks and may include pre-flood, floodevent or post-flood activities. Flood Risk Management Plans (FRMP) Plans which are developed in accordance with national flood policy and the EU Floods Directive and which provide the strategic direction for flood risk management decisions in a catchment. These will describe a range of traditional river or coastal defences to non-structural responses such as flood warning and resilience measures at property level. Terms Definition 58
- Flood storage The temporary storage of excess run-off or river flow in ponds, basins, reservoirs or on the floodplain. Flood zones A geographic area for which the probability of flooding from rivers, estuaries or the sea is within a particular range as defined within these Guidelines. Flooding Directive The EU Directive 2007/ 60/ EC of 23 October 2007 on the assessment and management of flood risks which is aimed at integrating the way flood risk is managed throughout the European Union. Fluvial flooding Flooding from a river or other watercourse. Groundwater flooding Flooding caused by groundwater escaping from the ground when the water table rises to or above ground level. Indicative Floodplain Map (IFM) A map that delineates the areas estimated to be at risk of flooding during an event of specified flood probability. Being indicative, such maps only give an indication of the areas at risk but, due to the scale and complexity of the exercise, cannot be relied upon to give precise information in relation to individual sites. Initial flood risk assessment A qualitative or semi-quantitative study to confirm sources of flooding that may affect a plan area or proposed development site, to appraise the adequacy of existing information, to provide a qualitative appraisal of the risk of flooding to development, including the scope of possible mitigation measures, and the potential impact of development on flooding elsewhere, and to determine the need for further detailed assessment. Inland flooding Any flooding away from the sea, the primary cause of which is prolonged and/or intense precipitation (or the failure of water-retaining infrastructure, such as burst water pipes or dam breaks). Terms Definition 59 Guidelines for Planning Authorities The Planning System and Flood Risk Management
- Justification Test An assessment of whether a development proposal within an area at risk of flooding meets specific criteria for proper planning and sustainable development and demonstrates that it will not be subject to unacceptable risk nor increase flood risk elsewhere. The justification test should be applied only where development is within flood risk areas that would be defined as inappropriate under the screening test of the sequential risk based approach adopted by this guidance. Likelihood (probability) of flooding A general concept relating to the chance of an event occurring. Likelihood is generally expressed as a probability or a frequency of a flood of a given magnitude or severity occurring or being exceeded in any given year. It is based on the average frequency estimated, measured or extrapolated from records over a large number of years and is usually expressed as the chance of a particular flood level being exceeded in any one year. For example, a 1 in 100 or 1% flood is that which would, on average, be expected to occur once in 100 years, though it could happen at any time. Mitigation measures Elements of a development design which maybe used to manage flood risk to a development, either by reducing the incidence of flooding both to the development and as a result of it and/or by making the development more resistant and/or resilient to the effects of flooding. Natura 2000 The EU-wide network of protected areas, recognised as ‘sites of Community importance’ under the EC Habitats Directive (Council Directive 92/43/EEC on the conservation of natural habitats and of wild fauna and flora). They comprise “Special Areas of Conservation” SACs) under the Habitats Directive and “Special Protection Areas” (SPAs) under the Birds Directive (Council Directive 79/409/EC on the conservation of wild birds). Overtopping of defences Failure of a flood defence or exceedance mechanism, when flood water reaches levels that are higher than the flood defence level and flows over the top of the structure. While the structure may remain stable, however, erosion of the landward face of the defence could cause the defence to collapse. Terms Definition 60
- Terms Definition Pathways These provide the connection between a particular source (e.g. high river or tide level) and the receptor that may be harmed (e.g. property). In flood risk management, pathways are often ‘blocked’ by barriers, such as flood defence structures, or otherwise modified to reduce the incidence of flooding. Pluvial flooding Usually associated with convective summer thunderstorms or high intensity rainfall cells within longer duration events, pluvial flooding is a result of rainfall-generated overland flows which arise before run-off enters any watercourse or sewer. The intensity of rainfall can be such that the run-off totally overwhelms surface water and underground drainage systems. Precautionary approach The approach to be used in the assessment of flood risk which requires that lack of full scientific certainty, shall not be used to assume flood hazard or risk does not exist, or as a reason for postponing cost-effective measures to avoid or manage flood risk. River Basin Management Plan (RBMP) As required by the EU Water Framework Directive (2000/ 60/ EC), these plans will establish a strategic plan for the long-term management of the River Basin District, set out objectives for waterbodies, and in broad terms identify what measures are planned to meet these objectives, and act as the main reporting mechanism to the European Commission. Regional Flood Risk Appraisal A desk-based study to provide a broad overview of the source and significance of flooding across a region and identify potential conflicts with existing and proposed areas of development, thus highlighting areas where further studies will be required at county or city scale as part of development plan preparation. Regional planning guidelines (RPG) These provide the regional context and priorities for applying national planning strategy to each NUTS III region and encourage greater co-ordination of planning policies at the city / county level. RPGs are an important part of the flood policy hierarchy as they can assist in co-ordinating flood risk management policies at the regional level. 61 Guidelines for Planning Authorities The Planning System and Flood Risk Management
- Resilience Sometimes known as “wet-proofing”, resilience relates to how a building is constructed in such a way that, although flood water may enter the building, its impact is minimised, structural integrity is maintained, and repair, drying & cleaning and subsequent reoccupation are facilitated. Resistance Sometimes known as “dry-proofing”, this relates to how a building is constructed to prevent flood water entering the building or damaging its fabric. Receptors Things that may be harmed by flooding (e.g. people, houses, buildings or the environment). Residual risk The risk which remains after all risk avoidance, substitution and mitigation measures have been implemented, on the basis that such measures can only reduce risk, not eliminate it. Run-off The flow of water, caused by rainfall, from an area which depends on how permeable the land surface is. Run-off is greatest from impermeable areas such as roofs, roads and hard standings and less from vegetated areas – moors, agricultural and forestry land. Sequential approach The sequential approach is a risk-based method to guide development away from areas that have been identified through a flood risk assessment as being at risk from flooding. Sequential approaches are already established and working effectively in the plan-making and development management processes. Site-specific Flood Risk Assessment An examination of the risks from all sources of flooding of the risks to and potentially arising from development on a specific site, including an examination of the effectiveness and impacts of any control or mitigation measures to be incorporated in that development. Source Source refers to a source of hazard (e.g. the sea, heavy rainfall). Terms Definition 62
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