Durham E-Theses Knowledge of, and response to, upland ash ooding: a case study of ood risk management of the 2005 ash ood in upper Ryedale, North Yorkshire, U.K. HOPKINS, JONATHAN How to cite: HOPKINS, JONATHAN (2012) Knowledge of, and response to, upland ash ooding: a case study of ood risk management of the 2005 ash ood in upper Ryedale, North Yorkshire, U.K., Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/5574/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk 2 Knowledge of, and response to, upland flash flooding: a case study of flood risk management of the 2005 flash flood in upper Ryedale, North Yorkshire, U.K. Jonathan Hopkins The dangerous hazard posed by flash flooding to upland communities is likely to increase due to climate change. The flood risk management policy approach has become predominant since the 1990s, with an emphasis on the public awareness of, and responses to, flood risks; however, the unpredictable nature of upland flash flooding means that responses to such hazards are uncertain. This thesis uses an integrated analysis of social and physical science datasets to study responses by local residents and the Environment Agency to flash flooding, using a case study of a major upland flood in North Yorkshire. Responses to flash flooding within upland communities were found to be mostly present as changes to individual behaviour and awareness. However, physical, damage reducing modifications were limited. Flash flood hazard perception was found to be linked to knowledge and experience of local flooding. Major flash flood events occurring in areas which have not experienced other recent floods are unlikely to increase perceptions or provoke responses. Although local awareness of changing weather patterns was found, supporting analyses of rainfall records, local flood risks were frequently framed in the context of river management, rather than climate change. The implementation of policy changes and responses to flash flooding by the Environment Agency will prove difficult at the local level, due to the nature of attitudes and perceptions encountered at the local level, including important differences in the perception of the flash flood hazard between local residents and representatives from nationwide organisations. Encouraging property-level modifications following flash floods, in accordance with national policies, is very difficult. In order to increase local perceptions of the flash flood hazard, the use of participatory work, focusing on long-term awareness raising and the sharing of locally held flood knowledge may be beneficial, alongside the support of existing resilience in upland communities. Knowledge of, and response to, upland flash flooding: a case study of flood risk management of the 2005 flash flood in upper Ryedale, North Yorkshire, U.K. Jonathan Hopkins Thesis submitted for the degree of Doctor of Philosophy Department of Geography University of Durham 2012 i Table of Contents Table of Contents i List of Tables vi List of Figures xii List of Equations xix Declaration and Statement of Copyright xx Acknowledgements xxi Dedication xxii Chapter 1 1 Introduction 1.1 Flooding in the U.K. 1 1.2 The upland flash flood hazard 3 1.3 Flash floods and the wider flood risk management context 11 1.4 Implications for research, and thesis objectives 18 1.5 Case study: upper Ryedale flash flood, 19th June 2005 20 1.6 Chapter summary, and thesis structure 29 Chapter 2 32 Literature review 2.1 Key definitions, and the nature of flood risk 32 2.2 Physical flash flood risks: climate change, heavy rainfall and river flows 34 2.3 Land use changes, river maintenance and flooding 36 2.4 Institutional responsibilities for dealing with flood risks, and recent policy 38 changes 2.5 Human decision making, hazard response, adaptation and preparedness 42 2.6 Hazard/risk perception 45 ii 2.7 Chapter summary 48 Chapter 3 52 Methodology 3.1 Interdisciplinary research 52 3.2 The natural hazards framework 58 3.3 Overview of data collection in this thesis 60 3.4 The use of quantitative and qualitative data in hazard response and 61 perception research 3.5 Research into past rainfall patterns and flooding: integration of physical 62 (quantitative) data with social science (quantitative and qualitative) data 3.6 Organisation of data and structure of analysis 66 3.7 Physical data collection and analysis 73 3.7.1 Rainfall 73 3.7.2 River discharge 80 3.8 Social science data collection and analysis 87 3.8.1 Interviews 87 3.8.2 Questionnaires 92 3.9 Chapter summary 103 Chapter 4 104 Reconstructing long-term upland rainfall series 4.1 Assessment of rainfall data 105 4.1.1 Annual and seasonal rainfall totals 105 4.1.2 Extreme and maximum rainfalls 108 4.1.3 Annual and seasonal trends in heavy rainfall 113 4.2 Comparison of local trends with heavy rainfall patterns observed 118 regionally, and in England and Wales 4.3 Private rainfall record analysis 126 4.4 Local perceptions of past rainfall in Helmsley 129 iii 4.5 Discussion and chapter summary 141 Chapter 5 149 Assessment of residents’ responses to flash flooding and local flood knowledge 5.1 Experience of flash flooding in 2005 152 5.2 Responses to flash flooding of Helmsley residents, and factors influencing 154 them 5.2.1 Responses to flash flooding 154 5.2.2 Factors influencing responses to flash flooding 156 5.2.2.1 Knowledge of Environment Agency flood warning and 159 flood information services 5.2.2.2 Actions taken since the 2005 flood 160 5.2.2.3 Perceived preparedness of residents and local authorities 161 5.2.2.4 Factors influencing flood hazard perception 163 5.2.3 Summary of factors influencing responses to flash flooding 166 5.3 Responses to flash flooding of households directly affected by flash 167 flooding, and factors affecting them 5.3.1 Summary of responses to flash flooding 167 5.3.1.1 Physical modifications 168 5.3.1.2 Behavioural changes 173 5.3.2 Factors influencing responses to flash flooding 176 5.3.3 Differences between questionnaire and interview responses 202 5.4 Assessment of links between river discharge and rainfall: a ‘pseudo flood’ 204 series 5.4.1 Description of methods 205 5.4.2 Analysis of high river flow events and daily rainfall records 208 5.4.3 Relationships between peak discharge and sub-daily rainfall events 211 5.4.4 Reconstructed possible overbank floods 213 5.5 Perceived factors influencing local flood risks 220 5.6 Discussion and chapter summary 226 iv Chapter 6 245 Institutional responses to flash flooding, and their implementation 6.1 Institutional difficulties in dealing with flash flooding 246 6.1.1 Difficulties in forecasting and predicting flash floods 247 6.1.2 Responsibilities for flood response 248 6.1.3 Difficulties in the local assessment of flood risk 250 6.1.4 Monitoring and technology issues 251 6.2 Institutional responses to flash flooding 254 6.2.1 Rapid response catchments 254 6.2.2 Engagement with local knowledge 257 6.2.3 Encouragement of local level resilience 260 6.2.4 Improvements to forecasting data 264 6.2.5 Changes to land use management 265 6.2.6 Changes to Environment Agency working patterns 267 6.3 Possibilities for flash flood warning systems in upland areas: a comparison 269 of upper Ryedale and Sinnington 6.4 Comparison of institutional viewpoints with local knowledge 274 6.4.1 Similarities between institutional and local viewpoints 274 6.4.2 Differences between institutional and local viewpoints 277 6.4.2.1 Views on the contributing factors to local flooding 277 6.4.2.2 Views on the way in which institutions and local residents 281 work together and communicate 6.4.2.3 Views on the perceived and actual responsibilities and 284 resources of the local authorities and Environment Agency 6.4.2.4 Views on the factors constituting a flood risk 286 6.5 Discussion and chapter summary 287 Chapter 7 302 Discussion 7.1 The wider context of flood risk management, and the upland flash flood 302 hazard v 7.2 Summary of responses to upland flash flooding by residents and the 303 Environment Agency, and factors influencing them 7.3 Contributions of this research towards upland flash flood mitigation and 317 understanding 7.4 Recommended responses to upland flash floods 337 Chapter 8 351 Conclusion 8.1 Summary of thesis findings 351 8.2 Thesis contributions, and recommendations for future research 354 Appendices Appendix 1 360 Sample interview outlines A1.1 Interview schedule 1: interviews with residents of upper Ryedale 361 A1.2 Interview schedule 2: interviews with spokesmen from the Environment 364 Agency A1.3 Interview schedule 3: interview with representative from Ryedale District 367 Council (main questions) Appendix 2 369 Questionnaire Appendix 3 376 Variables used within the questionnaire analysis Appendix 4 381 Statistically significant relationships from the rainfall and discharge analysis A4.1 Tabular summary of statistically significant relationships found within 382 Chapter 4 A4.2 Statistically significant relationships between rainfall and discharge found 386 within Chapter 5 References 388 vi List of Tables Table 1.1: Generalised characteristics of plain (or lowland) and flash flood events.