Integrated analysis of risks of coastal flooding and cliff erosion under scenarios of long term change

TitleIntegrated analysis of risks of coastal flooding and cliff erosion under scenarios of long term change
Publication TypeTyndall Working Paper
SeriesTyndall Centre Working Papers
Tyndall Consortium Institution

Southampton

Secondary TitleTyndall Centre Working Paper 110
Keywordscliff erosion, coastal flooding, Integrated analysis, long term change, risks, scenarios
AuthorsDawson, R., M. E. Dickson, R. J. Nicholls, M. Walkden, P. Stansby, M. Mokrech, J. Richards, J. Zhou, J. Milligan, A Jordan, and S. Pearson
Year of Publication2007
Abstract

The risks to human populations in coastal areas are changing due to climate and socio-economic changes, and these trends are likely to accelerate during the 21st Century. To understand these changing risks, and the resulting choices and pathways to successful management and adaptation, broad-scale integrated assessment is essential. Due to their complexity these two risks are usually managed independently, yet frequently they are interconnected by longshore exchange of sediments and the resulting broad scale morphological system behaviour. Simply put, if beach levels fall, flood risk in adjacent low-lying coastal areas increases and vice versa. In order to generate new insights into the effects of climate change and coastal management practises on coastal erosion and flood risk, we present an integrated assessment of 72 km of shoreline over the 21st Century on the East Anglian Coast of England. A coupled system of hydrodynamic, morphological, reliability and socio-economic models has been developed for the analysis, which has been implemented under scenarios of climate and socio-economic change. The study is unique in coastal management terms because of the large spatial scale and extended temporal scales over which the analysis is quantified, but is also a site of significant controversy about how to manage flood and erosion risks in the coming Century. This study for the first time quantifies what has for some years been argued qualitatively: the role of sediments released from cliff erosion in protecting neighbouring low-lying land from flooding. The losses and benefits are expressed using the common currency of economic risk. The analysis demonstrates that over the 21st Century, flood risk in the study area is expected to be an order of magnitude greater than erosion risk. Both climate and socio-economic change can have a significant influence on flood risk. This study demonstrates that the choices concerning coastal management are profound, and there are clear tradeoffs between erosion and flood impacts – avoiding cliff erosion can increase flood risk, and vice versa.

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