Effectiveness of Ecosystem-Based Coastal Defenses Against Flooding

Coastal flooding is growing substantially as storms increase and sea levels rise rapidly due to climate change. It is therefore important to find safe and sustainable ways to protect coastal communities against this growing risk. However, the effectiveness of traditional coastal defenses (hard seawalls) (HS) is being questioned due to concerns about their negative ecological impacts and high economic cost. Ecosystem-Based Coastal Defenses (EBCDs) may potentially offer a more sustainable alternative. Based on a systematic literature review of >21,000 articles from 430 vulnerable areas, here we argue that EBCDs do not always provide effective protection, especially where EBCDs have seasonal vegetation cover, and in intertidal habitats in sediment-starved areas. We suggest that HS might be employed in a hybrid approach, together with EBCDs, to optimize flood protection and environmental benefits in these areas. We also consider how “intelligent HS,” using adaptive materials, might be applied in future coastal flood protection systems.