The Impact of Eco-retrofitting on Coastal Resilience Enhancement – A Physical Modelling Study

Abstract

Recent climate change studies highlight that the sea-level rise and increase in intensity and frequency of extreme climatic events and storm surges will result in catastrophic wave overtopping events from coastal defences. Retrofitting of the existing seawalls provides great potentials for enhancement of the climatic resilience in coastal region through overtopping attenuation. With increasing attention towards sustainable and low emission solutions for improving the resilience of critical infrastructures to natural hazards, providing coastal protection service is no longer the only concern of scientists, but the environmental impacts of such interventions also started to be considered. This paper presents a laboratory-scale investigation of ‘eco-retrofitting’ approaches including vertipools and reef breakwater for their impact on mitigating overtopping from seawall. The laboratory tests were conducted on a vertical seawall with 1(V):20(H) smooth foreshore. Each test was consisted of approximately 1000 pseudo-random waves based on JONSWAP spectrum. Both impulsive and non-impulsive wave conditions were tested. The plain vertical seawall was taken as the reference case, that exhibited an overall good agreement with empirical predictions, when compared to EurOtop. The analysis of data highlights the significance of the tested eco-interventions in mitigating wave overtopping volume, with approximately 70% reduction of mean the overtopping rate.