Flooding: Changes Around the Firth Mark McLaughlin Senior Hydrologist (Flood Map Manager) Scottish Environment Protection Agency Firth of Clyde Forum - 11 November 2008

Content  Flood events around the Firth  Climate change and the potential impacts  SEPA’s role Flood Risk Mapping: Indicative River & Coastal Flood Map (Scotland) - Future development Flood Warning  Future changes – European Directive on Assessment and Management of Flood Risks  Conclusions

Recent Flood Events Around the Firth of Clyde  January 1991 – result of a significant tidal surge Flooding along the Ayrshire coast (Saltcoats) Highest observed levels at Greenock, Tarbert, Saltcoats, Millport & Rothesay  January 1993 – tidal surge  Significant surge levels in October 2008 (+1m) – no flooding though

Flood Events in the Firth of Clyde – Stevenston/Saltcoats

Flood Events in the Firth of Clyde – Helensburgh

Flood Events in Loch Fyne – Tarbert

Potential Impacts of Future Climate Change  More variation in weather patterns  Increased storminess  Increase in sea level  Increasing frequency of significant surge events  Increased rainfall/fluvial flooding (summer too)

Climate change and flooding – UKCIP02 predictions  20% increase in river flows by 2080  1% probability event becomes a 2% event by 2080  30cm increase in mean sea level by 2080  Increased storminess - wave and storm surges  Daily mean temperature increase 4oC by 2080

Percentage Change in Wave Height (winter periods and )

Days of Heavy Rain - >10mm/day (Change 1961 – 2004)

Changing River Flows

Impacts of Climate Change Economic Social Environmental

SEPA’s Role in Managing Flood Risk Currently:  Planning Advice Mapping  Flood Warning Schemes (rivers and coastal) In the (very near) future:  European Directive on the Assessment and Management of Flood Risks

Section 25 of Environment Act requires that SEPA provides Local Planning Authorities, upon request, with advice on the risk of flooding based on the information which it holds. Town & Country Planning Act - SEPA is a statutory consultee on developments at flood risk SEPA’s Role – Flood Risk

To support our role as a statutory consultee To raise public awareness To support planning policy and guidance Borders 1977 Development of a Flood Map for Scotland

Maps are the most effective way of communicating information on flood risk at a local, regional and national level to planners, developers and residents. Why do we need flood maps ?

Development of the Indicative River & Coastal Flood Map (Scotland) Summary of the Flood Map project:  Funded by Scottish Executive - £1.3m  Contract awarded in 2004  Completed 2006  Public Launch on SEPA web site November 2006

 To map 3 extreme flood events (100yr, 200yr and 1000yr) in rivers and coastlines around Scotland  Utilised industry standard, generic methodologies  Utilised automated processes to allow large amounts of modelling to be done in a short time  Supplemented by detailed model outputs where available Indicative River & Coastal Flood Map (Scotland)

Fluvial Maps Key datasets and methodologies have recently become available which now allows us to use computer models to amalgamate the data and allow us to generate a national flood map cost effectively. Creating the Maps The NEXT MAP digital terrain model is a detailed high resolution map of Scotland

Estimates of 100yr, 200yr and 1000 year flood flows at every 50m grid point along 25,000km of river was used to generate a water depth in the floodplain. For the fluvial flood maps, the data was imported into hydraulic modelling software linked to a GIS framework Creating the Maps

Coastal Maps Coastal flood outlines created using Proudman Oceanographic Laboratory (POL) extreme sea level method and projected inland over the Digital Terrain model Creating the Maps

Limitations of the Flood Map  No specific consideration of flood defences  No inclusion of hydraulic structures  No specific inclusion of other types of flooding  Limitations of the methodology  The Flood Map provides a strategic level of information and is not suitable for individual property assessment, but is a flood management tool to support development planning.

Future Map Development  Improved topographic information (LiDAR) Particularly for urban areas  Refinement of the estimation of the extreme design flows  Improved modelling (calibration against recorded events)  Coastal development Improved representation of bathymetry, especially for sea lochs  Development of Flood Risk & Hazard Maps in line with current European Directives

SEPA’s Role - Flood Warning  SEPA is the Flood Warning Authority in Scotland (Environment Act 1995)  FW relies on effective partnerships  SEPA provide a 24/7 flood warning service.  Hydrologists monitor flood events and issue warnings to the public via the police, local authorities and ‘Floodline’.  Hydrologists maintain communication with LA’s, emergency services and the Hydro- electric companies throughout the year.

SEPA’s coastal flood warning strategy  SEPA has developed a coastal flood warning strategy  Includes a vision for a nationally integrated flood warning service for coastal communities  Has two phases: 1.A flood watch service for broad coastal areas covering the entire Scottish coast 2.A flood warning service for specific at-risk communities  The strategy is supported by the Scottish Government

Key elements of the strategy  Improving our understanding of risk  Improving our understanding of coastal processes  Identifying the resources required  Working with partners  Seeking funding  Integrating with existing flood warning schemes – Firth of Clyde

Coastal Flood Watch for Scotland  Live February 2007  Uses alerts from the Met Office  Based on 9 Coastal Zones  28 forecast points  Issued through Floodline  Local Authorities/Police informed of flood watch

Storm Tide Forecast Service CS 3 model Forecast points

European ‘Floods’ Directive  Directive 2007/60/EC on the Assessment and Management of Flood Risks  Objective: ‘the establishment of a framework for measures to reduce the risks of flood damage’  Currently being transposed into Scots Law

European ‘Floods’ Directive  Identification of Competent and Responsible authorities  Scale – river basin districts  Three elements: 1.Preliminary Flood Risk Assessment by December Development of Flood Hazard & Risk Maps by December Flood Risk Management Plans by December 2015

European ‘Floods’ Directive  Recognises that floods are natural phenomena which cannot be prevented but that some human activities (including increasing development on floodplains) and climate change contribute to an increase in the likelihood and adverse impacts of flood events  Integrated approach to managing flood risk on river basin and sub-basin scale  There are therefore clear links with SEPA’s duties on Flood Risk and Flood Warning in overall flood risk management

Conclusions  With respect to flooding, there is a potential for significant changes in the area of the Firth of Clyde.  Physical – potential increased risk as a result of climate change  Legislative – integrated approach to flood risk management as a result of European directions and Scots Law