Analysing Flood and Erosion Risks and Coastal Management Strategies on the Norfolk Coast

Abstract

Coastal systems are characterised by variability and interdependencies at a range of scales. On the Norfolk coast from Weybourne to Winterton in SMP6, variations in sediment supply, from cliff erosion and beach nourishment, have a profound influence upon the probability of failure of the flood defences that protect the large area of coastal lowlands, including the Norfolk Broads. The risk of flooding is therefore influenced by large-scale and long-term changes in sediment supply as well as by short-term fluctuations which are dominated by the arrival of extreme storms. The reliability of the flood defences also plays a crucial mediating role on the probability of flooding. When flooding does occur, the extent and severity of damage is influenced by patterns of inundation and the human and economic vulnerability of the communities that are flooded. This chapter brings together science from several of the preceding chapters in order to analyse how the risks of flooding and erosion will change in the future. The analysis makes use of a Monte Carlo simulation methodology, which takes multiple simulations of beach levels (from the SCAPE model described in Chap. 7) and combines this with reliability analysis of the flood defence system, quantification of the inundation depth and extent (from Chap. 8) and changes in coastal vulnerability and land use (from Chap. 4). The evolution of future flood risk is sensitive to the quantity of beach sediment, from eroding cliffs or artificial beach nourishment, underlining the importance of strategic coastal management. In the Tyndall Coastal Simulator, the work constitutes a key result and builds on the paper by Dawson et al. (Proc R Soc Lond A 462(2075):3343–3362, 2009). It demonstrates that erosion and flood risk are strongly linked. Alternatively, nourishment can substitute for the sources from cliff erosion. Many of the results from this work are taken forward in the visualisation work (Chap. 10), the interface development (Chap. 11) and the stakeholder interaction (Chap. 12).