Weathering the Storm: A Decision-making Framework to Support Flood Adaptation Policy in New York City

Abstract

New York City has experienced a long history of flooding from coastal storms, but as projections of future sea level rise, population and economic growth increase, so too will the risk of flooding in New York City. It is generally accepted that adaptive risk management strategies will be needed to guard against uncertain risk of future flooding. A key question facing policymakers has to do with determining when investments in flood risk reduction strategies are justified. Policymakers, however, face significant challenges when considering investments in long-term flood adaptation strategies due to the uncertainties surrounding future climate change and socioeconomic development. This problem is compounded by the dynamic nature of flood risk as more information about uncertain futures becomes available. Moreover, investments in flood adaptation strategies involve significant costs and uncertain near-term and long-term payoffs, which create additional challenges for making costly investment decisions in long-term flood adaptation strategies. In this thesis, I develop an integrated decision-making framework to support flood adaptation decisions in New York City. The integrated decision-making framework combines elements from a number of existing formal decision-making frameworks, including the “context first” approach, “Real Options” approach, multi-objective optimization analysis, and principles of robustness. This thesis contributes the integration of real policymakers at the center of the formal decision-making framework for New York City. Further, I show that, while flood adaptation decision-making poses significant difficulties for decision-makers, policy implementation is the true barrier to effective flood risk management. Drawing on lessons from the Thames Barrier and Thames Estuary 2100 project in the United Kingdom and the current situation in New York City in the post-Hurricane Sandy environment, this thesis acknowledges the value of taking into consideration the political context, in addition to projected future climate and socioeconomic factors, when determining how adaptation decisions ought to be made.