| dc.description.abstract | Worldwide, deltas are increasingly threatened by anthropogenic stress. Adapting to these threats is a pressing and unavoidable necessity, as currently more than 500 million people live in and depend on deltas. Paradoxically, conventional approaches to address flood risks are rigid, they cause, exacerbate or facilitate existing threats, and they result in the deterioration of surrounding ecosystems. A robust and flexible alternative is nature-based adaptation (NbA), which aims to preserve natural ecosystems. It assumes that dynamic ecosystems are resilient and can provide cost-effective protection against threats, conserve biodiversity, and provide benefits to communities.
However, adaptation capacities are limited which may result in losses and damages. Therefore, to sustainably manage deltas, it is critical to gain a better understanding of the potential for NbA in different contexts. This thesis studies the feasibility of NbA in the Rhine and Mekong deltas, two highly contrasting cases. First, a systematic literature review was conducted to compile the set of existing NbA options in deltas and coasts. Next, environmental and policy constraints to NbA were assessed. I argue that sea-level rise, subsidence, sediment availability and land-use may constrain NbA in deltas. Data on these variables were obtained and analysed. Additionally, I contend that adaptive governance is a prerequisite for the implementation of NbA. Toward that end, the Rhine and Mekong delta plans were analysed using the adaptive governance framework by DeCaro et al. (2017a).
Currently, only nine NbA strategies for deltas exist in the literature. Although most principles for adaptive governance are present in the delta plans, indicating that from a policy perspective there are opportunities for NbA in the Rhine and Mekong deltas, from an environmental perspective NbA is highly constrained. Seven of the nine NbA strategies face serious implementation constraints in the Rhine and Mekong deltas due to projections of environmental change. Therefore, there is an urgent need to combine strategies for mitigation, adaptation, and dealing with loss & damage. This also has implications for governance. As NbA is highly constrained, adaptive governance alone is not the best framework to manage future challenges. I contend that combining adaptive, transformative and interactive governance may be the best way to sustainably manage the Rhine and Mekong deltas.
These results enhance our understanding of the potential for NbA to address anthropogenic stress in the Rhine and Mekong deltas, and potentially in other deltas worldwide too. In addition, the results open up important new questions for future research. | |
