Coastal Wetlands CR0422 Final Report
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DEFRA Developing Tools to Evaluate the Consequences for Biodiversity of Options for Coastal Zone Adaptation to Climate Change (CR0422) A study modelling the risk of loss from flooding of lowland open-water and wetland priority BAP habitats in the coastal floodplain under a range of sea-level rise scenarios 17 March 2011 Copyright and Non-Disclosure Notice The contents and layout of this report are subject to copyright owned by Entec (© Entec UK Limited 2011) save to the extent that copyright has been legally assigned by us to another party or is used by Entec under licence. To the extent that we own the copyright in this report, it may not be copied or used without our prior written agreement for any purpose other than the purpose indicated in this report. The methodology (if any) contained in this report is provided to you in confidence and must not be disclosed or copied to third parties without the prior written agreement of Entec. Disclosure of that information may constitute an actionable breach of confidence or may otherwise prejudice our commercial interests. Any third party who obtains access to this report by any means will, in any event, be subject to the Third Party Disclaimer set out below. Third-Party Disclaimer Any disclosure of this report to a third-party is subject to this disclaimer. The report was prepared by Entec at the instruction of, and for use by, our client named on the front of the report. It does not in any way constitute advice to any third-party who is able to access it by any means. Entec excludes to the fullest extent lawfully permitted all liability whatsoever for any loss or damage howsoever arising from reliance on the contents of this report. We do not however exclude our liability (if any) for personal injury or death resulting from our negligence, for fraud or any other matter in relation to which we cannot legally exclude liability. © Entec UK Limited Page ii 17 March 2011 © Entec UK Limited Page iv 17 March 2011 Contents 1. Introduction 1 1.1 Background 1 1.2 Scope of the project 1 1.3 Purpose of this report 3 1.4 What makes this project different? 4 1.5 Project uncertainties 5 2. Priority BAP habitats 7 2.1 Mapping of BAP habitats 7 2.1.1 Data sources 8 2.1.2 Verification of the habitat data 9 2.1.3 Derivation of alternative BAP habitat datasets 10 2.1.4 Distribution of the selected BAP habitats relative to the coastal floodplain 12 2.2 Sensitivity of the selected BAP habitats to saline inundation 13 2.2.1 Effects of saline inundation on BAP habitats 14 2.2.2 Development of sensitivity criteria 15 2.2.3 Sensitivity matrices for BAP habitats 18 2.2.4 Conclusion 22 2.3 Ease of creation of BAP habitats 24 2.3.1 Potential criteria for ranking ease of habitat creation 24 2.3.2 Ranking of ease of habitat creation 27 3. Modelling Approach 31 3.1 Context 31 3.2 General risk assessment concepts 32 3.3 The national flood risk assessment (NaFRA) 34 3.4 Use of the UK climate projections 2009 34 3.5 Assessment of risk to habitats 35 3.5.1 Current risk of habitat loss and further losses in the future 36 3.6 Modelling calculation: worked example 36 3.7 Comparison of outlined methodology with existing approaches 37 3.8 Quality audit 38 3.9 Uncertainty 39 © Entec UK Limited Page v h:\projects\ea-210\24903 coastal biodiversity and climate 17 March 2011 change\docs\outputs - deliverables\final project report\rr075i3.doc 4. Assessment of the area of BAP habitat at risk of loss as a result of coastal flooding 41 4.1 Context 41 4.2 Assessment of areas of BAP habitat at risk of loss 41 4.3 Headline observations 46 4.3.1 Habitats at risk of loss within the coastal floodplain 46 4.3.2 Habitats at risk of loss within designated sites in the coastal floodplain 48 4.3.3 Habitats at risk of loss in Environment Agency regions in the coastal floodplain 49 5. Implications for BAP habitats in England 51 5.1 Projected habitat losses - Overview of Impacts 51 5.2 Legal and conservation policy drivers 52 5.2.1 Implications of the projected losses for European sites 53 5.2.2 Implications of the projected losses for meeting BAP targets 54 6. Conclusions and Suggestions 59 6.1 Conclusions 59 6.2 Suggestions 61 7. References 65 Table 2.1 Comparison of published extents/estimates with nationally mapped habitat extents and project-derived habitat inventories for the selected BAP habitats 12 Table 2.2 Habitat extents in the inventories and percentage in the coastal floodplain 13 Table 2.3 Scale for risk assessment 16 Table 2.4a Reedbed Matrix (habitat only - not accounting for faunal species interest) 23 Table 2.4b Reedbed Matrix (accounting for faunal species interest) 23 Table 2.5b Low-Salinity Saline Lagoon Matrix 23 Table 2.6 Eutrophic Standing Waters (Lakes) Matrix 23 Table 2.7 Ponds Matrix 23 Table 2.8 Coastal and floodplain grazing marsh (ditches) 23 Table 2.9 Grazing Marsh Grass Matrix 23 Table 2.10 Lowland Fen Matrix 23 Table 2.11 Wet Woodland Matrix 23 Table 2.12 Purple Moor Grass and Rush Pasture Matrix 23 Table 2.13 Lowland Raised Bog Matrix 23 Table 2.15 Final ranked list of practical ease of habitat creation 27 Table 3.1 Risk assessment scenarios 35 Table 4.1 Extents of all selected BAP habitats within the coastal floodplain at risk of loss 43 Table 4.2 Extents of all selected BAP habitats within SSSIs in the coastal floodplain at Risk of Loss 44 Table 5.1 Extents of all selected BAP habitats within the coastal floodplain at risk of loss (sample of modelled scenarios) 52 Table 5.4 Estimated costs of replacing habitat at risk of loss 58 Figure 1.1 1 in 1,000 year tidal and tidal/fluvial flood zone 2 After Page 6 Figure 2.1 Comparison of national mapped habitat data (top left) with site habitat map (bottom right) After Page 30 Figure 3.1 The source-pathway-receptor-consequence model of flood risk assessment After Page 40 © Entec UK Limited Page vi h:\projects\ea-210\24903 coastal biodiversity and climate 17 March 2011 change\docs\outputs - deliverables\final project report\rr075i3.doc Figure 3.2 Habitat X at site X After Page 40 Figure 4.1 Area and percentage of selected habitat at risk of loss under 2100 medium with degraded Defences scenario in 1 in 1,000 year tidal and tidal/fluvial flood zone 2 After Page 50 Figure 4.2 Coastal and floodplain grazing marsh extent and areas at risk under scenario 2100 medium with degraded defences in 1 in 1,000 year tidal and tidal/fluvial flood zone 2 in environment agency anglian region After Page 50 Figure 4.3 Lowland raised bog extent and areas at risk under scenario 2100 medium with degraded defences in 1 in 1,000 year tidal and tidal/fluvial flood zone 2 in northern England After Page 50 Figure 4.4 Deciduous woodland extent and areas at risk under scenario 2100 medium with degraded defences in 1 in 1,000 year tidal and tidal/fluvial flood zone 2 in environment agency southern region After Page 50 Appendix A Project Brief Appendix B Project Organisation Appendix C Sources of Mapping Data and GIS Process Undertaken to Derive Lakes and Ponds Datasets Appendix D Details of the Habitat Verification Process Appendix D1 Habitat Verification Data Appendix E Extracts from BAP Priority Habitat Statements Appendix F1 Details of Consultations Undertaken to Inform the Sensitivity Matrices Appendix F2 Summary of Evidence Used to Populate Draft Risk Matrices Appendix G Details of the Workshop Appendix G1 Workshop Materials Circulated in Advance Appendix H Ease of Habitat Creation Scoring Approach and Ranking Analysis Appendix I Summary Evidence and References Supporting the Scoring Decisions Appendix J1 NaFRA Model - Step-by Step Explanation Appendix J2 Modelling Calculation: Worked Example Appendix K Habitat Extents at Risk of Loss Within Each Type of Designated Area and Outside Designated Areas Appendix L Habitat Extents at Risk of Loss Within Environment Agency Regions Appendix M Coastal and Floodplain Grazing Marsh BAP Targets (from BARS) © Entec UK Limited Page vii h:\projects\ea-210\24903 coastal biodiversity and climate 17 March 2011 change\docs\outputs - deliverables\final project report\rr075i3.doc © Entec UK Limited Page viii h:\projects\ea-210\24903 coastal biodiversity and climate 17 March 2011 change\docs\outputs - deliverables\final project report\rr075i3.doc 1. Introduction 1.1 Background Climate change is widely recognised as one of the major drivers of global biodiversity change and loss, with sea-level rise and increased frequency of extreme events, such as storms and flooding, being among the main agents. Policy responses need to use existing climate projection guidance to anticipate the effects on habitats at the coast, including freshwater, brackish and saline habitats behind the current natural and defended coastline. Strategies to conserve biodiversity need to be designed and implemented in a timely way so as to facilitate adaptation at the coast and, where constraints on adaptation result in habitat losses, to maximise the opportunities for habitat re-creation inland. There are several legal and Government policy drivers for the restoration and creation of habitats that are increasingly vulnerable at the coast. For example, there are a number of targets agreed under the UK Biodiversity Action Plan (UK BAP) for habitat restoration and/or creation.