Decision-making on local flood risk measures in area development in unembanked areas

Abstract

Cities worldwide are facing increasing impacts from climate hazards such as heavy precipitation, heat stress, flooding, and drought, exacerbated by climate change. This study focuses on unembanked areas (NL: buitendijkse gebieden), vulnerable to flooding due to factors like sea-level rise, river peak discharges, and land subsidence. However, there are many plans for (re)development in Dutch unembanked areas for the coming years. To address these challenges and avoid passing on consequences of what we build now to future generations, effective adaptation measures are crucial. The study investigates the decision-making process for local flood risk measures in unembanked areas, examining appropriate evaluation methods and stakeholders' needs. Qualitative research methods, including expert interactions, a literature review, case studies, and interviews, were employed. Although there are not evaluation methods, the Dutch multi-level safety approach and resilience-based planning methods like adaptative pathway and adaptative tipping point were found applicable to guide the decision-making process in unembanked area development.
For evaluation methods, multi-criteria analysis (MCA) emerged as a suitable tool for decision-making in unembanked area development, considering social values and intangible criteria. Combining MCA with cost-effectiveness analysis (CEA) or a form of cost-benefit analysis (CBA) proved effective in balancing quantitative and qualitative criteria, facilitating inclusive decision-making. The research emphasizes the extensive involvement of various stakeholders and identifies barriers related to legal aspects, risk awareness, and communication. Stakeholders call for well-defined guidelines, legal regulations, and collaboration between private and public entities. The study recommends establishing principles for unembanked area development and translating them into MCA criteria, addressing both social values and local characteristics. Further research is suggested to address legal assurance for climate-adaptive construction, increase awareness, enhance flood risk assessment methods and communication, and strengthen collaboration between private and public stakeholders in flood risk management and spatial planning.