QUANTIFYING THE BELGIAN COAST’S RESILIENCE AGAINST SEA LEVEL RISE (USING XBEACH and SWASH MODELLING)

Abstract

To maintain however a safe and climate resilient coast, it is utterly important to bridge the knowledge gap between its current safety level and its safety level under sea level rise. That’s why this year’s safety assessment includes also 3 mean sea level rise scenario’s: +0.3, +0.8 and +1.5m. It allows us to quantify the strength of the sea defense under changing hydraulic conditions and, possibly, identify its tipping point. Applying joint probability analysis and extreme value statistics on long time series of field data (monitored on the Belgian continental shelf) results in combinations of wind, water level and significant wave height having a specific (higher) return period. These combinations are then transformed from offshore to nearshore (just outside the surf zone) using SWAN. The Belgian coast is subdivided in alongshore coastal areas having similar median grain sizes. For every area, a 2DH XBeach model is set up, making use of a digital elevation model (DEM) of the present situation (February 2022).