Nature-based solutions for coastal climate change adaptation: sand nourishment strategies in the Netherlands

Abstract

Nature-based solutions (NbS) are increasingly regarded as promising approaches to coastal climate change adaptation, but it is not yet known how and why trade-offs occur and how to balance them. This interdisciplinary thesis evaluated NbS for coastal climate adaptation to support strategic decision-making, focusing on sand nourishment in the Netherlands. Sand nourishment strategies present conflicts, potentially ambiguous outcomes and feedback effects on coastal multifunctionality and policy goals. Information used in decision-making on NbS strongly differs between the stages and stakeholders involved. Nourishment strategies provide high multifunctionality in the coming decades, but require balancing different aspects of nature, recreation and flood safety. Deep uncertainty hinders adopting NbS due to the increased uncertainty of multifunctionality and adaptivity. The Dutch public prioritised clean coastal waters and different distributive justice principles depending on the benefits provided. Integrating these findings shows that NbS present a two-sided coin to strategic decision-making on coastal adaptation with short-term benefits, but that can bring ‘wicked’ trade-offs, increase vulnerability and challenge effective adaptation in the longer term. Adopting NbS thereby risks a lock-in. Strategic decision-making can adopt NbS for the coming decades, but the flexibility to transition to other adaptation strategies should be strengthened and investment in vulnerable areas limited.