Establishment and survival of coastal mangrove trees under mechanical disturbances

Abstract

Coastal flood risk will increase over the coming decades as sea level rise accelerates, storm patterns change and coastal populations grow. This will likely lead to a surge in costs to build and maintain reliable flood safety infrastructure. Hence, innovative nature-based solutions that use coastal ecosystems are gaining attention. Nature-based flood defence is a potentially sustainable and cost-effective solution to reduce coastal flood risk, that can be carried out with ecosystems such as mangrove forests, saltmarshes or coral reefs. Mangrove forests are increasingly studied for nature-based flood defence across the subtropical and tropical latitudes, as their sturdy vegetation can effectively attenuate flow energy from waves – surge attenuation with mangroves remains less well understood. Wider and denser forests provide more wave attenuation. As mangroves naturally fluctuate in size, so does their wave attenuation capacity. Consequently, to reliably estimate the safety of a mangrove-based flood defence, it is necessary to understand the long-term development of the mangrove forest. The studies presented in this thesis contribute important datasets and mechanistic principles that can be used to advance mangrove forest development models and estimate long-term flood protection capacity with coastal mangroves.

Integrating mangroves in dike designs: effect of tree growth and failure

“…For instance, dynamic effects in the forces are neglected, and we only model forces experienced at the edge of a forest (without considering sheltering effects between trees). We schematize the overturning strength as a function of the tree weight, but the shape and size of the root system will also influence tree stability 86 . Erosive and accretive processes will also affect the chances of failure, since they can they modify the resisting moment of the tree.…”