Volume 3 Specific Built Heritage Objectives - Draft Cork City Development Plan 2022-2028
26 July 2021
Draft Plan Stage
Cork City Strategic Flood Risk Assessment Report
S TRATEGIC F LOOD R ISK A SSESSMENT
FOR THE
D RAFT C ORK C ITY D EVELOPMENT P LAN 2022-2028
Cork City Council City Hall Anglesea Street Cork
for:
by:
CAAS Ltd. 1 st Floor 24-26 Ormond Quay Upper Dublin 7
J ULY 2021
Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
Table of Contents
Introduction and Policy Background.......................................................1
1.1 Introduction and Terms of Reference .................................................................................1 1.2 Summary of Conclusion and Recommendations ...................................................................1 1.3 Flood Risk and its Relevance as an Issue to the Plan............................................................1 1.4 Flood Risk Management Policy ...........................................................................................2 1.5 Emerging Information and Disclaimer .................................................................................5 1.6 Content of the City Development Plan ................................................................................5 Stage 1 SFRA - Flood Risk Identification ................................................7 2.1 Introduction .....................................................................................................................7 2.2 Drainage, Defences and Early Warning Systems ..................................................................7 2.3 Other Flood Studies ..........................................................................................................9 2.4 Flood Risk Indicators.........................................................................................................9 2.5 Conclusion of Stage 1 SFRA.............................................................................................10 Stage 2 SFRA - Flood Risk Assessment .................................................11 3.1 Introduction ...................................................................................................................11 3.2 Findings and Adequacy of Existing Information and Delineation of Flood Zones....................11 3.3 Flood Risk Zone Mapping.................................................................................................11 3.4 Sensitivity to Climate Change...........................................................................................12 Recommendations.................................................................................13 4.1 Introduction ...................................................................................................................13 4.2 Land Use Zoning.............................................................................................................13 4.3 Integration of other provisions relating to flood risk management into the Plan....................15 4.4 Justification Tests ...........................................................................................................17 Conclusion .............................................................................................20
Appendix I Summary of the requirements of the Flood Guidelines for land uses in Flood Zones
Appendix II Flood Mapping
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Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
Introduction and Policy Background
1.1 Introduction and Terms of Reference Cork City Council has prepared the Draft Cork City Development Plan 2022-2028 hereafter referred to as the “Draft Plan”. The preparation of the Draft Plan is undergoing an appropriate level of Strategic Flood Risk Assessment (SFRA) in accordance with The Planning System and Flood Risk Management - Guidelines for Planning Authorities (Department of the Environment, Heritage and Local Government and Office of Public Works, 2009) and Department of the Environment, Community and Local Government Circular PL 2/2014. The SFRA provides an assessment of flood risk and includes mapped boundaries for Flood Risk Zones. The SFRA in an ongoing process, alongside the Plan-preparation process, and will be updated to take into account, for example, any new information or any future changes to the Draft Plan on foot of submissions. 1.2 Summary of Conclusion and Recommendations The purpose of this document is to detail the findings of the SFRA that is being undertaken alongside the preparation of the Draft Plan. The SFRA has informed the Draft Plan and enables compliance with the Flood Risk Management Guidelines. All SFRA recommendations – including those related to land use zoning and flood risk management provisions – have been integrated into the Draft Plan. 1.3 Flood Risk and its Relevance as an Issue to the Plan 1.3.1 Flood Risk Flooding is an environmental phenomenon and can pose a risk to human health as well as causing economic and social effects. Some of the effects of flooding are identified on Table 1 below. Certain lands within the City have the potential to be vulnerable to flooding and this vulnerability could be exacerbated by changes in both the occurrence of severe rainfall events and associated flooding. Local conditions such as low-lying lands and slow surface water drainage can increase the risk of flooding. Table 1 Potential effects that may occur as a result of flooding
Tangible Effects
Intangible Human and Other Effects
Damage to buildings (houses) Damage to contents of buildings Damage to new infrastructure e.g. roads
Loss of life Physical injury Increased stress
Loss of income
Physical and psychological trauma Increase in flood related suicide
Disruption of flow of employees to work causing knock on effects Enhanced rate of property deterioration and decay
Increase in ill health
Long term rot and damp
Homelessness Loss of uninsured possessions
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Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
1.4 Flood Risk Management Policy 1.4.1 EU Floods Directive
The European Directive 2007/60/EC on the assessment and management of flood risk aims to reduce and manage the risks that floods pose to human health, the environment, cultural heritage and economic activity. The Directive applies to inland waters as well as all coastal waters across the whole territory of the EU. The Directive requires Member States to: Carry out a preliminary assessment by 2011 in order to identify the river basins and associated coastal areas where potential significant flood risk exists (preliminary mapping was prepared and a list of Areas for Further Assessment finalised in 2012). Prepare flood extent maps for the identified areas (finalised in 2016 for inclusion in Flood Risk Management Plans – see below). Prepare flood risk management plans focused on prevention, protection and preparedness. These plans are to include measures to reduce the probability of flooding and its potential consequences. These Plans were adopted in 2018. Implementation of the EU Floods Directive is required to be coordinated with the requirements of the EU Water Framework Directive and the current National River Basin Management Plan. 1.4.2 National Flood Policy Historically, flood risk management focused on land drainage for the benefit of agricultural improvement. With increasing urbanisation, the Arterial Drainage Act, 1945, was amended in 1995 to permit the Office of Public Works (OPW) to implement localised flood relief schemes to provide flood protection for cities, towns and villages. In line with changing national and international paradigms on how to manage flood risk most effectively and efficiently, a review of national flood policy was undertaken in 2003-2004. The review was undertaken by an Inter-Departmental Review Group, led by the Minister of State at the Department of Finance with special responsibility for the OPW. The Review Group prepared a report that was put to Government, and subsequently approved and published in September 2004 (Report of the Flood Policy Review Group, OPW, 2004). The scope of the review included a review of the roles and responsibilities of the different bodies with responsibilities for managing flood risk, and to set a new policy for flood risk management in Ireland into the future. The adopted policy was accompanied by many specific recommendations, including: Focus on managing flood risk, rather than relying only flood protection measures aimed at reducing flooding; Taking a catchment-based approach to assess and manage risks within the whole-catchment context; and Being proactive in assessing and managing flood risks, including the preparation of flood maps and flood risk management plans. 1.4.3 National CFRAM Programme The national Catchment Flood Risk Assessment and Management (CFRAM) programme commenced in Ireland in 2011. The CFRAM Programme is intended to deliver on core components of the National Flood Policy, adopted in 2004, and on the requirements of the EU Floods Directive. The Programme is being implemented through CFRAM studies that have been undertaken for each of the river basin districts in Ireland.
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Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
The CFRAM Programme comprises three phases as follows: The Preliminary Flood Risk Assessment 1 (PFRA) mapping exercise, which was completed in 2012; The CFRAM Studies and parallel activities, with Flood Risk Management Plans finalised in 2018; and Implementation and Review. The Programme provides for three main consultative stages as follows: Consultation for the PFRA mapping that was adopted in 2012; Consultation for Flood Extent mapping, that was finalised in 2016 for inclusion in Flood Risk Management Plans; and Consultation for Flood Risk Management Plans, that were adopted in 2018. The OPW is the lead agency for flood risk management in Ireland. The coordination and implementation of Government policy on the management of flood risk in Ireland is part of its responsibility. The European Communities (Assessment and Management of Flood Risks) Regulations 2010 (S.I. No. 122) identifies the Commissioners of Public Works as the ‘competent authority’ with overall responsibility for implementation of the Floods Directive 2007/60/EC. The OPW is the principal agency involved in the preparation of CFRAM Studies. 1.4.4 Flood Risk Management Guidelines 1.4.4.1 Introduction In 2009, the OPW and the then Department of the Environment and Local Government (DEHLG) published Guidelines on flood risk management for planning authorities entitled The Planning System and Flood Risk Management - Guidelines for Planning Authorities . The Guidelines introduce mechanisms for the incorporation of flood risk identification, assessment and management into the planning process. Implementation of the Guidelines is intended to be achieved through actions at the national, regional, local authority and site-specific levels. Planning authorities and An Bord Pleanála are required to have regard to the Guidelines in carrying out their functions under the Planning Acts. The core objectives of the Guidelines are to: Avoid inappropriate development in areas at risk of flooding; Avoid new developments increasing flood risk elsewhere, including that which may arise from surface water run-off; Ensure effective management of residual risks for development permitted in floodplains; Avoid unnecessary restriction of national, regional or local economic and social growth; Improve the understanding of flood risk among relevant stakeholders; and Ensure that the requirements of EU and national law in relation to the natural environment and nature conservation are complied with at all stages of flood risk management. 1.4.4.2 Principles of Flood Risk Management The key principles of flood risk management set out in the flood Guidelines are to: Avoid development that will be at risk of flooding or that will increase the flooding risk elsewhere, where possible; Substitute less vulnerable uses, where avoidance is not possible; and Mitigate and manage the risk, where avoidance and substitution are not possible.
1 The PFRAs identified areas at risk of significant flooding and includes maps showing areas deemed to be at risk. The areas deemed to be most significant risk, where the flood risk that is of particular concern nationally, are identified as Areas for Further Assessment (AFAs). AFAs were identified within the Plan area include Cork City, Douglas, Glanmire, Togher and Tower.
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Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
The Guidelines follow the principle that development should not be permitted in flood risk areas, particularly floodplains, except where there are no alternative and appropriate sites available in lower risk areas that are consistent with the objectives of proper planning and sustainable development. Development in areas that have the highest flood risk should be avoided and/or only considered in exceptional circumstances (through a prescribed Justification Test ) if adequate land or sites are not available in areas that have lower flood risk. Most types of development would be considered inappropriate in areas that have the highest flood risk. Only water-compatible development such as docks and marinas, dockside activities that require a waterside location, amenity open space, outdoor sports and recreation and essential transport infrastructure that cannot be located elsewhere would be considered appropriate in areas of highest risk. 1.4.4.3 Stages of SFRA The Flood Risk Management Guidelines recommend a staged approach to flood risk assessment that covers both the likelihood of flooding and the potential consequences. The stages of appraisal and assessment are: Stage 1 Flood risk identification – to identify whether there may be any flooding or surface water management issues related to either the area of Regional Spatial and Economic Strategies, Development Plans and Local Area Plans or a proposed development site that may warrant further investigation at the appropriate lower-level plan or planning application levels. Stage 2 Initial flood risk assessment – to confirm sources of flooding that may affect a Plan area or proposed development site, to appraise the adequacy of existing information and to scope the extent of the risk of flooding which may involve preparing flood zone maps. Where hydraulic models exist the potential impact of a development on flooding elsewhere and of the scope of possible mitigation measures can be assessed. In addition, the requirements of the detailed assessment are scoped. Stage 3 Detailed flood risk assessment – to assess flood risk issues in sufficient detail and to provide a quantitative appraisal of potential flood risk to a proposed or existing development or land to be zoned, of its potential impact on flood risk elsewhere and of the effectiveness of any proposed mitigation measures. 1.4.4.4 Flood Zones Flood risk is an expression of the combination of the flood probability or likelihood and the magnitude of the potential consequences of the flood event. It is normally expressed in terms of the following relationship: Flood risk = Likelihood of flooding x Consequences of flooding Likelihood of flooding is normally defined as the percentage probability of a flood of a given magnitude or severity occurring or being exceeded in any given year. For example, a 1% Annual Exceedance Probability (AEP) indicates the severity of a flood that is expected to be exceeded on average once in 100 years, i.e. it has a 1 in 100 (1%) chance of occurring in any one year. Consequences of flooding depend on the hazards associated with the flooding (e.g. depth of water, speed of flow, rate of onset, duration, wave-action effects, water quality) and the vulnerability of people, property and the environment potentially affected by a flood (e.g. the age profile of the population, the type of development and the presence and reliability of mitigation measures). 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.
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Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
There are three types of flood zones defined for the purposes of the Flood Guidelines:
Flood Zone A – where the probability of flooding from rivers and the sea is highest (greater than 1% or 1 in 100 for river flooding or 0.5% or 1 in 200 for coastal flooding); Flood Zone B – where the probability of flooding from rivers and the sea 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 from rivers and the sea is low (less than 0.1% or 1 in 1000 for both river and coastal flooding). Flood Zone C covers all other areas that are not in zones A or B. A summary of the requirements of the Flood Guidelines for land uses across each of the above flood zones is provided at Appendix I . 1.5 Emerging Information and Disclaimer It is important to note that compliance with the requirements of the Flood Risk Management Guidelines is currently based on emerging and best available data at the time of preparing the assessment, including Flood Risk Management Plans, which will be updated on a cyclical basis as part of CFRAM activities. The SFRA process for the Draft Plan is ongoing and will be updated as relevant, including to take account of any Material Alterations that arise during the Plan-preparation process. Following adoption of the Plan, information in relation to flood risk may be altered in light of future data and analysis, by, for example, the OPW, or future flood events. As a result, all landowners and developers are advised that Cork City Council and their agents can accept no responsibility for losses or damages arising due to assessments of the vulnerability to flooding of lands, uses and developments. Owners, users and developers are advised to take all reasonable measures to assess the vulnerability to flooding of lands and buildings (including basements) in which they have an interest prior to making planning or development decisions. Any future SFRAs for the area will integrate other new and emerging data. 1.6 Content of the City Development Plan The Draft Cork City Development Plan is a land use plan and overall strategy for the proper planning and sustainable development of the functional area of Cork City over the six-year period 2022-2028. The Plan comprises a series of separate, but closely linked and interrelated elements. The Plan comprises two volumes: Volume 1 – Written Statement Volume 2 – Mapped Objectives Volume 3 – Built Heritage Objectives The structure of the Written Statement is as follows: Chapter 1 – Introduction Chapter 2 – Core Strategy Chapter 3 – Delivering Homes and Communities Chapter 4 – Transport and Mobility Chapter 5 – Climate and Environment Chapter 6 – Green and Blue Infrastructure, Open Space and Biodiversity Chapter 7 – Economy and Employment Chapter 8 – Heritage, Arts and Culture Chapter 9 – Environmental Infrastructure and Management Chapter 10 – Key Growth Areas and Neighbourhood Development Sites Chapter 11 – Placemaking and Managing Development Chapter 12 – Land Use Zonings Chapter 13 – Implementation Appendix 1 – Compliance with Ministerial Guidelines Appendix 2 – Strategic Environmental Assessment Appendix 3 – Appropriate Assessment Appendix 4 – Strategic Flood Risk Assessment
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Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
The Strategic Vision for Cork City included in the Plan is for Cork City to take its place as a world class city, driving local and regional growth, embracing diversity and inclusiveness and growing as a resilient, healthy, age-friendly and sustainable compact city with placemaking, communities and quality of life at its heart. This Strategic Vision is based on the following Key Strategic Principles: Compact growth: Integrate land-use and transport planning to achieve a compact city with 50% of all new homes delivered within the existing built-up footprint of the City on regenerated brownfield, infill and greenfield sites identified in the Core Strategy, and to achieve higher population densities aligned with strategic infrastructure delivery. A city of neighbourhoods and communities: Develop a sustainable, liveable city of neighbourhoods and communities based on the 15-minute city concept, ensuring that placemaking is at the heart of all development. Sustainable and active travel: To implement the Cork Metropolitan Area Transport Study (CMATS) and develop a transformed sustainable transport system with a significant shift toward walking, cycling and public transport and to enshrine this principle in all developments across the City. Enhanced built and natural heritage Protect, enhance, support and develop our built and natural heritage, our open spaces and parks, and our green and blue infrastructure, and expand our built heritage with new buildings, townscapes and public spaces achieved through the highest standards of architecture and urban design. A strong and diverse economy: Support Cork City’s role as the economic driver for the region and the creation of a strong, resilient, diverse and innovative economy. A resilient City: Contribute to a framework for the transition to a low-carbon and climate-resilient City, resilient to extreme weather events, pandemics, economic cycles and other potential shocks. A healthy, inclusive and diverse city: Build on Cork City’s status as a World Health Organisation designated Healthy City, offering an inclusive and vibrant environment for all whilst promoting healthy living and wellbeing. A connected city: Cork City will continue to be a highly connected city providing local, regional, national and international connectivity. A city of learning and culture: To build on Cork’s designation as a UNESCO Learning City and the city’s rich cultural heritage and to foster learning, culture, heritage and the arts throughout the City. The most relevant parts of the Plan for this SFRA relate to land use zoning and provisions relating to flood risk management 2 .
2 Flood risk management recommendations made by the SFRA process and integrated into the Draft Plan are provided under Section 4.
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Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
Stage 1 SFRA - Flood Risk Identification
2.1 Introduction Stage 1 SFRA (flood risk identification) was undertaken in order to identify whether there may be any flooding or surface water management issues within or adjacent to zoned lands and consequently whether Stage 2 SFRA (flood risk assessment) should be proceeded to. Cork City is subject to the Flood Risk Management Plan for the Lee, Cork Harbour and Youghal Bay River Basin (UOM19). Stage 1 SFRA is based on existing information on flood risk indicators based on historical evidence and computational models. Appendix II (pages 3-7) show the spatial distribution of City-wide historical and predictive flood risk indicators. Appendix II also provides larger scale maps of these historical and predictive indicators for areas within the City. 2.2 Drainage, Defences and Early Warning Systems With regard to areas benefitting from drainage and defences (flood relief scheme works), there are various measures that have been implemented in Cork City that will contribute towards flood risk management. These include the culverting of various streams and rivers in many urban areas. Embankments and associated predicted benefitting lands under a number of historical government schemes are mapped in Appendix II . The Flood Risk Management Plan for the Lee, Cork Harbour and Youghal Bay River Basin identifies various general measures under “Measures Applicable for all Areas”, including under the headings of: Sustainable Planning and Development Management Sustainable Urban Drainage Systems (SUDS) Adaptation Planning Land Use Management and Natural Flood Risk Management Maintenance of Channels not part of a Scheme Flood Forecasting and Warning Emergency Response Planning Promotion of Individual and Community Resilience Individual Property Protection Flood-Related Data Collection Voluntary Home Relocation With regard to Cork City (the City Centre), the Flood Risk Management Plan identifies two key measures as follow: Progress a Flood Relief Scheme for Lower Lee, Cork City (Status: Stage II: Planning Process) The proposed Lower Lee (Cork City) Flood Relief Scheme was initiated in 2013 following major flooding in 2009 and 2012 and includes flood defences along the River Lee downstream of Inniscarra dam and through Cork city, changes to the operating procedures for the Carrigadrohid and Inniscarra reservoirs for the purposes of flood risk management and a flood forecasting system to help guide decision-making on dam discharges and, if necessary, the erection of temporary / demountable defences downstream and in Cork City. The Scheme is expected to provide protection against the 100-year fluvial flood (1.0% Annual Exceedance Probability) from the River Lee, and against the 200-year tide (0.5% Annual Exceedance Probability) for about 2,100 properties. Progress a Flood Relief Scheme for the Bride River, Blackpool (Status: Stage II: Public Exhibition / Confirmation) The proposed Bride River (Blackpool) Flood Relief Scheme was initiated in 2013 following major flooding in 2012 and includes conveyance improvement, flood defence embankments and walls, and pumping stations. The scheme is expected to provide protection against the 100-Year flood (1% Annual Exceedance Probability) for about 285 properties from the Bride River.
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Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
With regard to Douglas and Togher, the Flood Risk Management Plan identifies the following key measure: Progress a Flood Relief Scheme for Douglas, including Togher Culvert (Status: Stage IV: Implementation/Construction) Project is being carried out in 3 Phases: Phase 1: Main Douglas Project, Construction of direct flood defences and conveyance improvement measures along the Ballybrack Stream, Grange Stream and Tramore River. The direct defences proposed include flood walls with the conveyance improvements consisting of channel widening, channel deepening and the replacement of culverts. Phase 2: Togher Culvert Service Diversions contract - Diversion of services on the L-2452 Togher prior to final phase. Phase 3: Togher Culvert main project -Construction of conveyance improvement measures, including a flood wall, along the Tramore River and replacement of culverts along the L-2452 Togher. With regard to Glanmire, the Flood Risk Management Plan identifies the following key measure: Progress a Flood Relief Scheme for Glashaboy FRS, Sallybrook/Glanmire (Status: Stage II: Public Exhibition / Confirmation) The proposed Glashaboy (Sallybrook/Glanmire) Flood Relief Scheme includes construction of new walls, construction of earthen embankments, upgrades and construction of new culvert, replacement of existing bridge with new reinforced bridge at Hazelwood Shopping Centre, clearance of bridge eyes at Riverstown Bridge and associated drainage works. The proposed scheme is expected to provide protection against a 100-Year fluvial flood (1% Annual Exceedance Probability). With regard to Tower, the Flood Risk Management Plan identifies the following key measure: Maintenance of the Existing Defences Undertake maintenance of the existing flood defences in Tower / Blarney. The provision of flood protection measures can significantly reduce flood risk. However, the Ministerial Guidelines require that the presence of flood protection structures should be ignored in determining flood zones. This is because of risks relating to failure and severe flood events that exceed design capacity (the risk of severe events is exacerbated with climate change). Notwithstanding this, new development can proceed in areas that are at elevated levels of flood risk subject to the Justification Test provided for by the Guidelines being passed, which takes into account proposals to manage flood risk, such as the development of defences. Although insurance can be challenging to attain in these instances. Various rivers and their banks and culverts in the City are maintained by the Office of Public Works/Cork City Council. The Plan provides various provisions for the protection of water courses and riparian zones, for example Development Management Paragraph Nos. 11.218 “Development proposals should incorporate an appropriately-sized buffer zone to maintain natural fluvial processes and to protect the water environment.…” and 11.219 “Development proposals should protect watercourses in accordance with Inland Fisheries Ireland’s “Planning for Watercourses in the Urban Area” including the protection of riparian sections of rivers and streams, where possible, as set out below. Existing development will be taken into account. (1) Protection of the streamside zone, (within 15m of riverbanks); (2) Utilisation of outer riparian buffer zone (>8m) for treatment and reduction of stormflow runoff; (3) Minimal disturbance of the corridor 15-30m from the river; (4) Explore opportunities for river corridors for access and use as local amenity; and (5) Encourage riparian buffer strips on agricultural land. Such protection will, in combination with the direction of development within the existing footprint of developed areas will help to safeguard flood plains from development throughout the City. Met Éireann currently issues flood warnings for Cork City. Met Éireann, in collaboration with the OPW, is currently engaged in the establishment of a National Flood Forecasting and Warnings Service to forecast for fluvial and coastal flood events.
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Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
2.3 Other Flood Studies Other Flood Studies considered in the preparation of this assessment include:
Flood Risk Management Plan (Lee, Cork Harbour and Youghal Bay River Basin), 2018; Websites and documentation for the following measures under the Flood Risk Management Plan including: o Lower Lee Flood Relief Scheme o Douglas Flood Relief Scheme o Glashaboy Flood Relief Scheme Previous relevant SFRAs in Cork City and County Regional Flood Risk Assessment for the Southern Regional Spatial and Economic Strategy. 2.4 Flood Risk Indicators Indicators of flood risk that are based on historical flooding events are identified and described on able 2 and mapped in Appendix II . Indicators of flood risk that are based on computational models – predictive flood risk indicators – are identified and described on Table 3 and mapped in Appendix II . able 2 Historical Flood Risk Indicators
Information Source
Description
Strategic Limitations
Recorded Flood Events from the OPW
This only provides a spot location dataset This only provides a spot location dataset
A flood event is the occurrence of recorded flooding at a given location on a given date. The flood event is derived from different types of information (reports, photographs etc.). A flood event that has occurred more than once at a certain area is named a recurring flood event. A flood extent is an inundated area as recorded at a certain moment in time. This layer of information includes floods recorded in 1999/2000 and 1954. Mineral alluvial soil mapping is indicative of recurrent or significant fluvial flooding at some point in the past and was generated by Teagasc with co-operation of the Forest Service, EPA and GSI. This project was completed May 2006. This drainage scheme mapping dataset was prepared on behalf of the Drainage Districts (Local Authorities with statutory responsibility for maintenance under the Arterial Drainage Act, 1925). These maps identify land that might benefit from the implementation of Arterial (Major) Drainage Schemes and indicate areas of land subject to flooding or poor drainage. This dataset indicates areas of land defended to some degree against flooding that were formerly the responsibility of the Land Commission.
Recurring Events
Flood
OPW Flood Extent
Coverage limited
Alluvium Soils
Drainage may have changed significantly since these soils were deposited. Identifies large broad areas - very low resolution for flood risk management
Drainage Districts (OPW)
Land (OPW)
Commission
Identifies broad areas - low resolution for flood risk management
Table 3 Predictive Flood Risk Indicators
Information Source
Description
Strategic Limitations
CFRAM Study, Flood Extent Mapping, 2016
Spatial spread is limited, including to the areas that are considered to be at most risk of flooding.
Following the undertaking of the PFRA, the OPW, through its engineering consultants and working with local authorities and other stakeholders, conducted extensive engineering assessments to better understand and detail the actual risk from flooding for areas that were at highest levels of risk. This was the subject of public consultation. The outcome of that work includes Predicted Flood Extent maps that were finalised in 2016. For fluvial flood levels, calibration and verification of the models make use of the best available data including hydrometric records, photographs, videos, press articles and anecdotal information. The OPW PFRA mapping dataset has been arrived at by: • Reviewing records of floods that have happened in the past; • Undertaking analysis to determine which areas might flood in the future, and what the impacts might be; and
OPW Flood
Preliminary
The PFRA is only a preliminary assessment, based on available or readily derivable information. Analysis has
Risk Assessment (PFRA) Fluvial, Groundwater and
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Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
Information Source
Description
Strategic Limitations
Pluvial flood maps, 2012 3
been to identify areas prone to flooding, and the risks associated with such flooding, but this analysis is purely indicative and undertaken for the purpose of completing the PFRA. The mapping has been developed using simple and cost-effective methods and is based on broad- scale simple analysis and may not be accurate for a specific location/use. undertaken
• Extensive consultation with each local authorities and other Government departments and agencies. This assessment has considered all types of flooding, including that which can occur from rivers, the sea and estuaries, heavy rain, groundwater, the failure of infrastructure, and so on. It has also considered the impacts flooding can have on people, property, businesses, the environment and cultural assets. Further information on the purpose and development of the OPW PFRA Maps are available on www.cfram.ie. National Coastal Protection Strategy Study flood and coastal erosion risk maps: the predicted flood extents that were produced under the Irish Coastal Protection Strategy Study (ICPSS) are based on analysis and modelling. The project included: Analysis of historic recorded sea levels Numerical modelling and statistical analysis of combined tide levels and storm surges to estimate extreme water levels along the national coastline for defined probabilities Calculation of the extent of the predictive flooding, by comparing calculated extreme tide and surge waters levels along the coast with ground level based on a Digital Terrain Model (DTM). These indicative national coastal flood maps are included in the Draft PFRA Maps, provided in a separate volume, for the purposes of consultation on the PFRA. The OPW NIFM project has produced second generation indicative fluvial flood spatial data that are of a higher quality and accuracy to those produced for the first cycle PFRA. This project has covered 27,000 km of river reaches, separated into 37 drainage areas, consisting of 509 sub-catchments.
National Indicative Fluvial Mapping (NIFM) 2021
Does not cover smaller sized catchments
2.5 Conclusion of Stage 1 SFRA The information detailed above indicates elevated levels of flood risk in various locations across the City; therefore, a Stage 2 SFRA has been proceeded to.
3 Appendix II of this assessment includes PFRA Fluvial and Coastal mapping. Pluvial and groundwater flood risk is present in the City, however; it is not taken into account in the delineation of flood zones. Nonetheless, it has informed the development of recommendations detailed in Section 4.
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Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
Stage 2 SFRA - Flood Risk Assessment
3.1 Introduction Stage 2 SFRA (flood risk assessment) has been undertaken to: Confirm the sources of flooding that may affect zoned and adjacent areas; Appraise the adequacy of existing information as identified by the Stage 1 SFRA; and Scope the extent of the risk of flooding through the preparation of flood zone maps. 3.2 Findings and Adequacy of Existing Information and Delineation of Flood Zones Desk and in-field studies were undertaken taking into account the following factors: OPW’s CFRAMS fluvial flood extent mapping and other predictive indicators; Historical indicators of flood risk; Documented local Council knowledge of flood risk; The potential source and direction of flood paths from the sea and rivers and streams; Vegetation indicative of flood risk; and The locations of topographic/built features that coincide with the flood indicator related boundaries/topographical survey. Within the annual exceedance probabilities specified by the Flood Guidelines for Flood Zones A and B, there are elevated levels of flood risk throughout the City, as shown in Appendix II . 3.3 Flood Risk Zone Mapping Flood Risk Zone maps have been produced taking into account the findings of the Stage 1 and Stage 2 SFRA desk and in field studies as identified above 4 . The maps are provided in Appendix II and identify Flood Zone A (darker blue) and Flood Zone B 5 (lighter blue). All other areas fall within Flood Zone C. As per the Guidelines, the flood zones in Cork City are as follows: Flood Zone A – where the probability of flooding from rivers and the sea is highest (greater than 1% or 1 in 100 for river flooding or 0.5% or 1 in 200 for coastal flooding); Flood Zone B – where the probability of flooding from rivers and the sea 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 from rivers and the sea is low (less than 0.1% or 1 in 1000 for both river and coastal flooding). Flood Zone C covers all other areas that are not in zones A or B.
4 Including taking into account predictive and historical indicators of flood risk, documented local Council knowledge of flood risk, the potential source and direction of flood paths from rivers and streams, vegetation indicative of flood risk and the locations of topographic/built features that coincide with the flood indicator related boundaries/topographical survey. 5 As identified by the Guidelines, in rivers with a well-defined floodplain or where the coastal plain is well defined at its rear, the limits of Zones A and B will virtually coincide. Zone B will only be significantly different in spatial extent from Zone A where there is extensive land with a gentle gradient away from the river or the sea.
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Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
3.4 Sensitivity to Climate Change ‘The Planning System and Flood Risk Management Guidelines for Planning Authorities and Technical Appendices, 2009' recommends that a precautionary approach to climate change is adopted due to the level of uncertainty involved in the potential effects. In this regard, the Guidelines recommends: Recognising that significant changes in the flood extent may result from an increase in rainfall or tide events and accordingly adopting a cautious approach to zoning land in these potential transitional areas; Ensuring that the levels of structures designed to protect against flooding such as flood defences 6 , land raising or raised floor levels are sufficient to cope with the effects of climate change over the lifetime of the development they are designed to protect (normally 85-100 years); and Ensuring that structures to protect against flooding and the development protected are capable of adaptation to the effects of climate change when there is more certainty about the effects and still time for such adaptation to be effective. Advice on the expected impacts of climate change and the allowances to be provided for future flood risk management in Ireland is given in the OPW Draft Guidance on Assessment of Potential Future Scenarios for Flood Risk Management (2009). Two climate change scenarios are considered. These are the Mid-Range Future Scenario (MRFS) and the High-End Future Scenario (HEFS). The MRFS is intended to represent a "likely" future scenario based on the wide range of future predictions available. The HEFS represents a more "extreme" future scenario at the upper boundaries of future projections. Based on these two scenarios the OPW recommended allowances for climate change in relation to river flows and sea levels are given in Table 4. These climate change allowances are particularly important at the development management stage of planning, and will ensure that proposed development is designed and constructed to take into account best current knowledge. Climate change allowances have been integrated into the recommendations provided at Section 4 of this report and MRFS and HEFS mapping is available from the OPW for certain areas, including AFAs, and provided in Appendix II to this SFRA report.
Table 4 Allowances for Future Scenarios (100-Year Time Horizon) 7
6 Defended areas are highly sensitive to climate change as the likelihood of defence failure and resulting flooding increases. 7 OPW Draft Guidance on Assessment of Potential Future Scenarios for Flood Risk Management (2009)
CAAS for Cork City Council
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Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
Recommendations
4.1 Introduction In order to comply with The Planning System and Flood Risk Management - Guidelines for Planning Authorities (Department of the Environment, Heritage and Local Government and Office of Public Works, 2009) and Department of the Environment, Community and Local Government Circular ( PL 2/2014 ) and contribute towards flood risk management within the Plan area, the recommendations below have been made by the SFRA process and integrated into the Draft Plan. 4.2 Land Use Zoning Text integrated into Chapter 11 “Placemaking and Managing Development” Flood Risk Assessment and Land Use Zoning Paragraph No. 11.256 The Flood Zones identified by the Strategic Flood Risk Assessment (refer to the SFRA report that accompanies the Plan) should be used in line with the requirements provided for by the Flood Guidelines for land uses in Flood Zones A and B. Paragraph No. 11.257 Land use zoning objectives provided by this Plan are subject to the following conditions: (1) Undeveloped land in Flood Zone A that is the subject of any zoning objective are only zoned for and shall only be developed for water compatible uses as identified in the Guidelines. (2) Undeveloped land in Flood Zone B that is the subject of any zoning objective are only zoned for and shall only be developed for water compatible or less vulnerable uses as identified in the Guidelines. (3) With respect to lands that have already been developed in Flood Zone A or B the potential conflict (between zoning and highly or less vulnerable development in Flood Zone A and between zoning and highly vulnerable development in Flood Zone B) will be avoided by applying the following zoning approach, subject to the exception areas set out in (iii) below: (i) Cork City Council will facilitate the appropriate management and sustainable use of these areas. This will mean generally limiting new development, but facilitating existing development uses that may require small scale development such as small extensions. Development proposals within these areas shall be accompanied by a detailed Flood Risk Assessment, carried out in accordance with The Planning System and Flood Risk Assessment Guidelines and Circular PL 2/2014 (or as updated), which shall assess the risks of flooding associated with the proposed development. (ii) Proposals shall only be considered favourably where it is demonstrated to the satisfaction of the Planning Authority that they would not have adverse impacts or impede access to a watercourse, floodplain or flood protection and management facilities, or increase the risk of flooding to other locations and be in accordance with the proper planning and sustainable development of the area. The nature and design of structural and non-structural flood risk management measures required for development in such areas (see relevant Flood Risk Assessments - section below) will also be required to be demonstrated, to ensure that flood hazard and risk will not be increased. Measures proposed shall follow best practice in the management of health and safety for users and residents of the development. (iii) Exceptional areas are the already developed City Centre and Docklands areas, which have undergone Justification Tests and have been zoned for development, and established built-up areas of Cork City including suburban areas such as Model Farm Road / Carrigrohane Road area and Douglas. Future development in these areas will: be subject to site-specific flood risk assessments; comply with the flood risk management provisions of this Plan, including the structural and non- structural risk management measures outlined under Flood Risk Assessments below, and relevant measures contained in the Council’s 2020 South Docks Drainage Strategy; and will benefit from Flood Relief Schemes being progressed by the OPW.
CAAS for Cork City Council
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Strategic Flood Risk Assessment for the Draft Cork City Development Plan 2022-2028
Flood Risk Assessments Paragraph No. 11.258
The Council will have regard to the Planning System and Flood Risk Management Guidelines for Local Authorities (DEHLG and OPW 2009) when assessing planning applications. All significant proposals for development identified as being vulnerable to flooding will be required to provide a site-specific Flood Risk Assessment (FRA) in accordance with the Guidelines. A detailed site-specific FRA should quantify the risks, the effects of selected mitigation and the management of any residual risks. Paragraph No. 11.259 Assessments shall consider and provide information on the implications of climate change with regard to flood risk in relevant locations. The 2009 OPW Draft Guidance on Assessment of Potential Future Scenarios for Flood Risk Management (or any superseding document) and available information from the CFRAM Studies shall be consulted to this effect. Paragraph No. 11.260 In Flood Zone C, where the probability of flooding is low (less than 0.1%, Flood Zone C), site- specific Flood Risk Assessment may be required and the developer should satisfy themselves that the probability of flooding is appropriate to the development being proposed. This Development Plan’s SFRA datasets and the most up to date CFRAM Programme mapping should be consulted by prospective applicants for developments in this regard and will be made available to Development Management processes in the Council. Paragraph No. 11.261 Further details are also included in Chapter 9 Environmental Infrastructure and Management. Paragraph No. 11.262 Applications for vulnerable development in flood risk zones, including within Flood Zones A and B in the City Centre and the Dockland areas and in areas at risk under the OPW’s Mid-Range Future Scenario, shall provide details of structural and non-structural risk management measures to include, but not be limited to specifications of the following: (1) Floor Levels In areas of limited flood depth, the specification of the threshold and floor levels of new structures shall be raised above expected flood levels to reduce the risk of flood losses to a building, by raising floor heights within the building structure using a suspended floor arrangement or raised internal concrete platforms. When designing an extension or modification to an existing building, an appropriate flood risk reduction measure shall be specified to ensure the threshold levels into the building are above the design flood level. However, care must also be taken to ensure access for all is provided in compliance with Part M of the Building Regulations. Where threshold levels cannot be raised to the street for streetscape, conservation or other reasons, the design shall specify a mixing of uses vertically in buildings - with less vulnerable uses located at ground floor level, along with other measures for dealing with residual flood risk. (2) Internal Layout Internal layout shall be designed and specified to reduce the impact of flooding (e.g. living accommodation, essential services, storage space for provisions and equipment shall be designed to be located above the predicted flood level). In addition, designs and specifications shall ensure that, wherever reasonably practicable, the siting of living accommodation (particularly sleeping areas) shall be above flood level. With the exception of single storey extensions to existing properties, new single storey accommodation shall not be deemed appropriate where predicted flood levels are above design floor levels. In all cases, specifications for safe access, refuge and evacuation shall be incorporated into the design of the development. (3) Flood-Resistant Construction Developments in flood vulnerable zones should specify the use of flood-resistant construction aimed at preventing water from entering buildings - to mitigate the damage floodwater caused to buildings. Developments should specify the use of flood resistant construction prepared using specialist technical input to the design and specification of the external building envelope – with measures to resist hydrostatic pressure (commonly referred to as “tanking”) specified for the outside of the building fabric. The design of the flood resistant construction shall specify the need to protect the main entry points for floodwater into buildings - including doors and windows (including gaps in sealant around frames), vents, air-bricks and gaps around conduits or pipes passing through external building fabric. The design of the flood resistant construction should also specify the need to protect against flood water entry through sanitary appliances as a result of backflow through the drainage system.
CAAS for Cork City Council
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