Engineers Ireland Water and Environmental Engineering Society The Irish Coastal Protection Strategy Study Background, Status and Outputs

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1 Engineers Ireland Water and Environmental Engineering Society The Irish Coastal Protection Strategy Study Background, Status and Outputs Jim Casey, Chartered Engineer, BEng., MIEI, MICE Office of Public Works 30 May 2011

2 Acknowledgements Office of Public Works Tony Smyth, Tom Bolger, Joshua Reilly Department of Agriculture, Marine & Food Gerard Farrell, John McHale RPS Adrian Bell, Malcolm Brian, Caroline Robinson, Naomi Shannon, Bjoern Elsaesser (QUB) Compass Informatics Paul Walsh

3 PRESENTATION OUTLINE Risks Coastal Flooding Coastal Erosion Climate Change ICPSS Background & Current Status ICPSS Current and Future Outputs WP1: GIS Coastal Database, DTMs & Aerial Photography WP2&3: Extreme Sea Level Predictions WP2&3: Coastal Flood Extent & Depth Maps WP4A: Coastal Erosion Hazard Maps WP9A: Integration of Climate Change into ICPSS Flood Maps WP6A: Development of Coastal Flood Forecasting System Summary and Conclusions

4 RISKS : COASTAL FLOODING Extensive coastal flooding has occurred in the past decade in many of our major urban centres - Dublin, Cork, Wexford, Bray and Arklow in Feb 2002 and Oct 2004 and in Waterford and Cork in March The Feb 2002 event ( ~ 1 in 70 yr RP) coincided with a storm surge of over 1m at Dublin Port. Extensive flooding followed in parts of Dublin City and along the Fingal Coastline.

5 RISKS : COASTAL FLOODING The mechanisms of coastal flooding are not always the same and can vary from location to location. They may be dominated by surge combined with astronomical tide or in some cases by wave overtopping. Always important to have a thorough understanding of the flood mechanism and of the relationship between sea and land levels which often are referenced to a different elevation datum e.g. Malin vs Chart Datum or Mean Sea Level. Access to good quality historical recorded tidal data is fundamental to understanding and managing the problem as is the ability to analyse this data. Photo courtesy Dublin City Co.

6 FLOODING EXAMPLES Waterford City, March 2008 Photo Courtesy of Waterford City Co

7 RISKS : COASTAL EROSION Previous studies (NCEC, 1991) suggest that approx km or 27% of National Coastline is at risk from erosion. Particularly high rates of erosion have been observed along parts of the soft Wexford and Wicklow coastlines. Typically m annually. This was confirmed by the ICPSS SE coast erosion assessment which found a mean annualised erosion rate of 0.6m for all SE coast erosion areas. Erosion generally results in loss of land and property, loss of natural beach defences and undermining of coastal structures. However important to appreciate that it is also a natural process and has many beneficial effects e.g. nourishment of adjacent beaches and creation of natural defences.

8 RISKS : COASTAL EROSION Beach erosion if left unchecked can often give rise to coastal flooding problems (e.g. Bray) The causes of erosion in Ireland have been varied human, wave, tide and wind induced. The solution to a problem in one location can often cause problems at adjacent sites. The current ICPSS is helping to define more fully the extend of erosion risk in Ireland using modern survey and analysis methods (Lidar, Aerial Survey & GIS) and through the production of strategic erosion hazard mapping.

9 EROSION EXAMPLES Whiting Bay, Co Waterford

10 RISKS : CLIMATE CHANGE IPCC AR4 Report Measured Climate Change and Impacts Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global sea level Global average sea level has risen since 1961 at an average rate of 1.8 [1.3 to 2.3] mm/yr and since 1993 at 3.1 [2.4 to 3.8] mm/yr.

11 RISKS : CLIMATE CHANGE IPCC AR4 Report Predicted Climate Change and Impacts Table SPM.1 shows model based projections of global average sea level rise for The projections do not include uncertainties in climate-carbon cycle feedbacks nor the full effects of changes in ice sheet flow, therefore the upper values of the ranges are not to be considered upper bounds for sea level rise

12 RISKS : CLIMATE CHANGE OPW Consideration of Climate Change in ICPSS Allow for two future scenarios, mid range and high end (MRFS and HEFS) For MRFS add 0.5m SLR and include for Glacial Isostatic Adjustment (GIA) For HEFS add 1.0m SLR and include for Glacial Isostatic Adjustment (GIA) GIA based on work of Shennan et al, Durham University Contours are in mm per annum and are derived from work of Shennan et al.

13 ICPSS Background ICPSS originally commissioned by the Department of Marine & Natural Resources as part of their coastal protection function and because the allocation of annual CP funding to local authorities required a more strategic approach. Phase 1 of the study, comprising a general overview of coastal protection in Ireland and internationally, commenced in 2003 with a draft report issued in October 2004 Following a review of the Phase 1 report it was decided to structure the subsequent elements of the project into a series of 9 primary work packages. Following transfer of responsibility for coastal flooding and coastal protection to OPW in January 2009 this project is now being managed by OPW.

14 ICPSS Background Scope and Generic Work Packages Following Phase 1 subsequent Work Packages were phased to cover different coastal geographic extents

15 ICPSS Current Status Phase 2 South East Coast (Dalkey to Carnsore Point Trial Area) Note: Status shown as colour code Green : complete, Amber : nearing completion and red : outstanding

16 ICPSS Current Status Phase 3A North East Coast (Dalkey to Carlingford Lough) Note: Status shown as colour code Green : complete, Amber : nearing completion and red : outstanding

17 ICPSS Current Status Phase 3B Status South Coast (Carnsore Point to Bantry Bay) Note: Status shown as colour code Green : complete, Amber : nearing completion and red : outstanding

18 ICPSS Current Status Phase 4 South West & West Coast (Bantry Bay to Killala Bay) Note: Status shown as colour code Green : complete, Amber : nearing completion and red : outstanding

19 ICPSS Current Status Phase 5 North West Coast (Killala Bay to Lough Foyle) Note: Status shown as colour code Green : complete, Amber : nearing completion and red : outstanding

20 ICPSS Current Outputs South East, North East & South Coast Outputs - (Phases 2 & 3) Classified Coastal Lidar Terrain Models (WP1) Coastal Aerial Photography 2003 Oblique & 2006 Plan (WP1) Predicted Extreme Sea Levels for Combined Tide & Surge, 0.1%, 0.5% AEP + (WP2&3) Coastal Flood Hazard Extent Maps 0.1% AEP & 0.5% AEP + (WP2&3) Coastal Flood Hazard Depth Maps 0.5% AEP (WP2&3) Coastal Erosion Hazard Maps, 2050 & 2030 (WP 4A) Confidence Mapping for above Flood & Erosion Maps (WP2&3) Economics Assessment of Value of Assessets at Risk (WP 4A, East Coast Only) Reports Incorporating the above Tidal & Surge Forecasting Capability Note: Above WP2, 3 & 4A East Coast outputs are currently available from the OPW website at following web link : * South Coast outputs will be available at same web link by mid June 2011.

21 ICPSS Future Outputs South West, West & North West Coast Outputs - (Phases 4 & 5) Classified Coastal Lidar Terrain Models in Lidar Coverage Areas (WP1) Coastal Aerial Photography 2003 Oblique & 2006 Plan (WP1) Predicted Extreme Sea Levels for Combined Tide & Surge, 0.1%, 0.5% AEP + (WP2&3) Coastal Flood Hazard Extent Maps 0.1% AEP & 0.5% AEP (WP2&3) Coastal Flood Hazard Depth Maps 0.5% AEP (WP2&3) Coastal Erosion Hazard Maps, 2050 & 2030 (WP4A) Confidence Mapping for above Flood & Erosion Maps (WP2&3) Reports Incorporating the above Tidal & Surge Forecasting Capability Future Scenario Coastal Flood Hazard Maps 0.5% AEP (WP9A All Phases 2-5) Note: Above outputs in bold are currently substantially complete. Those underlined are at draft stage. Others available by end of this year or early 2012.

22 WP1: Development of GIS Coastal Database Coastal Lidar Digital Terrain Models, DTM 2m Res Cork Similar information available for entire east coast, south coast from Carnsore Point to Cork Harbour and many of the urban centres along south west and west coast e.g. Tralee, Limerick, Ennis, Galway & Sligo Coastal Lidar Digital Terrain Models, DTM 2m Res Dublin

23 WP1: Development of GIS Coastal Database Coastal Lidar Digital Terrain Models, DTM 2m Res Limerick City

24 WP1: Development of GIS Coastal Database Coastal Lidar Coverage The current coverage of coastal Lidar is shown in red on the Figure. It covers the entire east and south coast to Cork Harbour. It covers the main urban centres along the south west and west coast to Sligo. The high resolution orthophotography covers the same extent excluding the south east coast from Dalkey to Carnsore Point.

25 WP1: Development of GIS Coastal Database National Digital Height Model Classification, IFSAR NDHM 5m Res Limerick City

26 WP1: Development of GIS Coastal Database Coastal High Resolution Aerial Ortho-Photography, 0.25m Res

27 WP1: Development of GIS Coastal Database Limerick City LiDAR DTM/High Resolution Ortho / DSM, 2006

28 WP1: Development of GIS Coastal Database Cork City High Resolution Aerial Ortho-Photography, 2006

29 WP1: Development of GIS Coastal Database Limerick City High Resolution Aerial Ortho-Photography, 2006

30 WP1: Development of GIS Coastal Database Coast of Ireland Oblique Imagery Survey 2003 (National Coverage) Web Link :

31 WP2 & 3: Extreme Sea Level Prediction Points Water Level prediction Point Locations East & South Coast Extreme Sea Levels in metres to Ordnance Datum Malin for the following AEPs have been predicted: 0.1 % 0.5 % 1 % 2 % 5 % 10 % 20 % 50 %

32 WP2 & 3: Extreme Sea Level Prediction Points Water Level prediction Point Locations South West (Incl Shannon Estuary), West & North West Coast

33 0.5 % AEP Extreme Sea Level Predictions North East Coast Dundalk Bay Area South East Coast Wexford Harbour Area

34 WP 2&3: Coastal Flood Extent Maps - Undefended 0.1 % & 0.5 % AEP Flood Extent Map Current Scenario

35 WP3: Coastal Flood Depth Maps - Undefended 0.5 % AEP Flood Depth Map Current Scenario

36 WP4A: Coastal Erosion Hazard Maps 2050 Current Scenario

37 WP4A: Coastal Erosion Hazard Maps 2030 Current Scenario

38 WP9A: Integration of Climate Change Effects Flood Maps Draft Mid Range Future Scenario 2100

39 WP6A: Development of a Coastal Flood Forecasting System Irish Sea Tidal Surge Model (ISTSM) Much progress has been made in recent years on the development of coastal storm surge forecasting systems and models. One such model (extent shown) is that of the Irish Sea Tidal Surge Model which was developed under the ICPSS The area covered by this models is shown here and extends to the Continental Shelf west of Ireland. The Model shown is a Mike 21 flexible mesh model. OPW in conjunction with RPS, Consulting Engineers and Met Eireann commenced trials in 2009 of this storm surge forecasting system with a view to evaluating and improving its capability.

40 WP6A: Development of a Coastal Flood Forecasting System Presentation of Forecast Tide & Surge ISTSM currently provides twice daily short range predictions of tide and surge for up to 72 hours in advance and once daily medium range predictions of surge for up to 144 hours ahead. Runs twice daily providing morning and evening forecasts which are uploaded to a web viewer. The model provides both low resolution forecasts with national coastal coverage at 15 locations and high resolution forecasts for Cork Harbour, Wexford Harbour, Dundalk Bay and Galway Bay

41 WP5: Development of a Coastal Flood Forecasting System Forecast Tide & Surge for WE of 5-6 December 2009 Tide and surge forecast generated for Dublin Bay on 4 December 2009 is shown. Peak surge forecast was approx 0.45m, max water level forecast was approx 2.0m OD Malin on Sunday 6 December pm tide at approx hrs. Recorded max water level at Dublin Port gauge on Sunday 6 December pm was 2.25m OD Malin at hrs DCC flood watch level for Dublin Bay is 2.3m OD Malin and flood warning level is 2.5m OD Malin Similar levels need identification in other major urban centres

42 Summary and Conclusions The background and current status of the ICPSS has been presented. The various aerial survey data sets used to generate the project outputs have been presented. Sample outputs in the form of classified digital elevation models, flood hazard maps and erosion hazard maps have been presented. Some of the GIS techniques and systems used have been discussed. For Project Publications consult OPW website at: * The ISTSM storm surge forecasting system developed under the ICPSS has been presented and discussed. The strategic coastal flood and erosion maps produced will be of particular interest to LA planners in considering future coastal development. The strategic coastal flood and erosion maps produced will be of particular interest to LA and Emergency Services in respect of the management of the potential risks associated with coastal flooding and erosion. More detailed flood hazard and risk mapping is being carried out under the OPW CFRAM programme.