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

Abstract

The risks to human populations in coastal areas are changing due to climate and socio-economic changes, and these trends are predicted to accelerate during the 21 st 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 rise or fall, flood risk in adjacent low-lying coastal areas decreases or increases respectively. 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 21 st 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 coastal flood and erosion risks over the 21 st 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 21 st 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.

Indicator-based assessment of climate-change impacts on coasts: A review of concepts, methodological approaches and vulnerability indices

“…First, vulnerability is spatially scale-dependent, depending on whether it is national, regional or local. Yoo et al (2011) claimed that the spatial scale of climate-change vulnerability assessments is often either too broad when focused on the national or regional scale (Thieler & Hammer-Klose, 1999, 2000a, 2000b, Bryan et al, 2001, Dominguez et al, 2005, Mokrech et al, 2008, Dawson et al, 2009 or too narrow when focused on coastal segments (Pendleton et al, 2005).…”

Planning for the Impacts of Sea Level Rise

“…Planned adaptation (by the socioeconomic system) can serve to reduce vulnerability by a range of (antici- In general, sea level rise will exacerbate existing pressures and problems; thus, there are important synergies in considering adaptation to climate change in the context of existing problems (Nicholls and Klein, 2005). In some cases, the focus of sea level rise and climate change may help identify "win-win" situations where adaptation measures for sea level rise are worthy of implementation just based on solving today's problems (Turner et al, 1995;Dawson et al, 2009;Hallegatte, 2009 in a cost-benefit sense, protection costs could also overwhelm the capacity of local economies, especially when they are small such as islands (Fankhauser and Tol, 2005;Nicholls and Tol, 2006 activity, these funding challenges should be an issue of international concern.…”

A multi-component flood risk assessment in the Maresme coast (NW Mediterranean)

“…To correctly define coastal management policies for successful flood risk management, given the spatial and temporal nature of flood risk, broad-scale integrated assessments are essential (Dawson et al 2009;de Moel et al 2015). Thus, in order to manage the coastal zone at a regional scale, a holistic approach is required where, in addition to the factors determining flood risk (hazards and consequences), the various flood processes acting at different temporal scales should be considered.…”