Exploration of spatial adaptation strategies for mitigating future coastal flood risk in the Netherlands

Abstract

The study explores the potential impact of accelerated sea level rise on coastal flood risk in the Netherlands, particularly focusing on the Plan B NL2200 approach. Sea levels are expected to rise faster than initially thought due to factors like Antarctica's melting ice. The Sea Level Rise Knowledge Program in the Netherlands investigates consequences and mitigation strategies, including the categories 'protect-open,' 'protect-closed,' 'advance,' and 'accommodate.' The research compares the effectiveness of multiple spatial adaptation strategies, with a specific emphasis on the Plan B NL2200 approach, which envisions a Netherlands without dikes.

The study analyzes various spatial adaptation strategies, while focusing on extreme sea level rise and storm surge conditions, using a probabilistic model. The first part evaluates different spatial adaptation strategies in an idealized coastal polder, considering factors like spatial impact and flood risk mitigation. Findings suggest that strategies involving complete dike reinforcement are effective in reducing flood risk. The second part applies these strategies to the real case study of Walcheren, comparing damage, casualties, and affected people. The results indicate that the plain dike-ring strategy with an increased safety standard (P2) is the most cost-effective for preserving Walcheren entirely.

Regarding the Plan B NL2200 approach, the study concludes that, for Walcheren, it does not perform as the best strategy. The primary dike-ring strategy with tightened safety standards is more effective due to lower costs, reduced risks, and no land relinquishment. The study recommends maintaining the current strategy for reinforcing primary dikes while enhancing safety standards to protect Walcheren, including Middelburg and Vlissingen. However, the findings may not directly apply to other Dutch coastal areas due to location-specific factors, urging further research, including sensitivity analyses, exploration of additional spatial adaptation strategies, and consideration of societal aspects related to the Plan B approach.