Designing Adaptive Policy Pathways for Sustainable Water Management under Uncertainty: Lessons Learned from Two Cases

Water management in river deltas is increasingly being challenged by pressures from population growth, sea level rise, increasing variability in river runoffs, and potential climate change. Adaptation to such changes is not only determined by what is known or anticipated at present, but also by what will be experienced and learned as the future unfolds, as well as by policy responses to social and water events. As a result, a pathway emerges. Instead of responding to surprises and making ad hoc decisions, exploring adaptation pathways into the future will provide indispensable support to water management decision-making. We have developed a structured approach for designing a dynamic adaptive policy based on the concepts of adaptive policy making and adaptation pathways. Such a policy can change over time in response to how the future unfolds, what is learned about the system, and changes in societal preferences. Ingredients of this approach are: (a) transient scenarios (time series of various uncertain developments such as climate change, economic developments, societal changes), (b) a methodology for exploring many options and sequences of these options across different futures, and (c) a stepwise policy analysis. We have applied the method to two cases, a hypothetical case based on a river branch in the lower Rhine Delta, and a realworld case for the Rhine Delta in the Netherlands. In this paper, we describe the approach and lessons learned based on these two cases.Multi Actor SystemsTechnology, Policy and Managemen