Wetlands are common features on coasts globally, covering around 756 thousand km2, with medium sea level rise scenarios (50 cm) likely to cause a loss of 46-59 % by 2100 (Spencer et al., 2016). While coastal populations are increasingly at risk from flooding and erosion, this is particularly the case on coasts fronted by wetlands (nation states with mangroves may face a coastal population rise from 1.8 billion to 2.8 billion between 2000 and 2025 (Dodd and Ong, 2008)). If wetlands provide effective natural coastal protection, we need to act now to (a) safeguard this protective element, and (b) understand how it provides protection from flooding and erosion.
We now know that coastal wetlands provide protection through both: the effect of their surface characteristics on water flow and their resistant structure. This talk will review some of the existing evidence for both, including our true-to-scale experiment in extreme storm surge conditions (such as those experienced in the North Sea in 1953 and in 2013), which showed that NW European salt marsh vegetation reduces non-breaking waves by 14-15 % in height over only 40 m distance during those extreme conditions.
While, the evidence is there that wetlands, such as salt marshes, markedly reduce the overtopping risk of landward sea defences and that they act as highly stable platforms, they are still rarely fully incorporated within flood and coastal erosion risk management plans/assessments. Given technological advances in field and remote sensing methods, the capture of information relating to the coastal protection function of vegetated foreshores is now becoming much easier. This talk will discuss possible ways forward for the more widespread incorporating of natural features into flood and coastal erosion risk management.
Dr Iris Möller received her Ph.D. in Geography 1997, for a doctoral dissertation on ‘Wave attenuation over saltmarsh surfaces’ at the University of Cambridge. After a short spell of working at HR Wallingford Ltd, she joined the University of Cambridge’s Coastal Research Unit as a Research Associate and Deputy Director. She took up a Full-Time College Lectureship in Physical Geography at Fitzwilliam College of the University of Cambridge in 2000. Since 2014, she has held a University Lectureship in Physical Geography (Coastal Processes) at the Department of Geography, alongside continuing her role as Deputy Director of the Cambridge Coastal Research Unit. As an internationally recognised scholar, Dr Möller researches complex shallow coastal environments with a strongly applied focus on improving coastal flood and erosion risk management. She has over 40 peer-reviewed publications in international journals and is currently the Principal Investigator on ten and Co-Investigator on three collaborative research grants. Her 2013 true-to-scale experiment on the natural protection provided by salt marsh vegetation has been described by a reviewer as “just mind blowing and the results therefore unique and of incredible importance”.
Sascha Klöpper, stellvertretender Exekutivsekretär des Gemeinsamen Wattenmeersekretariats (Common Wadden Sea Secretariat; CWSS)