The key to successful storm surge protection

Date: 10 June 2016

Introduction: Researcher Jeroen Stark (UAntwerp) shows that a good design can shift the balance between a catastrophic flooding and efficient protection.

Tidal marsh restoration is often implemented to protect coastal areas against storm floods. Researcher Jeroen Stark shows that a good design can shift the balance between a catastrophic flooding and efficient protection.

Sea level rise and increasing storminess as a result of climate change force society to find new sustainable solutions for coastal flood protection. In this context, ecosystem-based adaptation to climate change is a promising approach. In particular, conservation or restoration of tidal wetlands and marshes is often implemented in addition to conventional coastal defence structures, such as dikes. In his new study, Jeroen Stark (Global Change Ecology Excellence Centre, research group Ecosystem Management) assessed the capacity of tidal wetlands to reduce high water levels during storm tides, and assessed the role of specific design characteristics.

Jeroen and his colleagues made a hydrodynamic model for ‘Het Verdronken Land van Saeftinghe’, a 3000 ha tidal marsh along the Scheldt Estuary. The model allows studying the effect of marsh channel depth, marsh elevation and marsh size on local storm surge reduction.


Aerial picture of the Saeftinghe marsh and its branching network of channels and creeks

Jeroen: “The model scenarios show that storm surge reduction is optimized in wider or larger marshes. In smaller marshes, a blockage effect against dikes minimizes water level reduction during larger storm events. The marsh channel depth determines the maximum amount of high water level reduction, with the highest high water level reduction rates for shallower channels. The elevation of the marsh platform has little effect on the maximum storm surge reduction.”

The platform elevation does however determine which storm tides are attenuated. Only so-called overmarsh tides that inundate the marsh platform are attenuated, while lower undermarsh tides are not attenuated or may even become higher in nearby areas. The work of Jeroen will assist coastal communities and managers in the optimization of the coastal protection function of tidal wetlands in combination with dikes.

The study was published in the scientific journal Estuarine, Coastal and Shelf Science.


Hydrodynamic model of the Saeftinghe marsh, showing the flooding of the marsh channels during high tide