7 – Flood Mapping

Mapping under Uncertainty: Spatial Politics, Urban Development, and the Future of Coastal Flood Risk

Policy makers often make decisions under uncertainty. Planners, therefore, increasingly use big data and sophisticated simulations to tackle their most difficult challenges. Disasters occur when these complex systems and their engineered solutions fail, and floods have accounted for six of the top ten catastrophes in American history, costing over $350 billion (NOAA National Centers for Environmental Information 2016). Recent losses and climate change projections have brought attention to the affordability of flood insurance and the cost of building to higher levels of protection (FEMA 2016). Crippled by claims and struggling with solvency, potential reforms of the National Flood Insurance Program (NFIP) are hampered by the fact that only 52% of the nation’s flood maps were considered accurate as of 2014, with an additional 4-10% becoming no longer current each year (Wilson 2014). Urban planners and developers, however, must reconcile scientific knowledge about floods in politicized local environments.

Given changing coastal flood risk and sea level rise, the dissertation asks: how can spatial politics inform the mapping of urban development under uncertainty? By examining communities in Greater Boston and New York City from the perspective of both practice and theory, I contrast a collaborative process where risk is changing place with contentious processes where is place changing risk, respectively. This informs how mapping acts as a decision support system at the local level, and I test these insights with the Boston Planning and Development Agency’s (BPDA) Article 37 Climate Change Preparedness Resiliency Checklist.

The dissertation frames an historical analysis of urban risk mapping to elucidate the translation process between models, standards, plans, and design. As such, it evaluates recent policy changes to the NFIP as well as the scope and purpose of Flood Insurance Rate Maps to determine whether they are adequate for the jurisdictional delineation of long-term urban development. Drawing upon jurisdictions with map changes from May 2014-May 2016, the dissertation uses mixed methods to compare how the two case study regions are engaged in contestation over risk classification, collaboration on mitigation strategies, and creation of scenario-based planning for climate adaptation.

The Greater Boston case in Plymouth County looks at near-term data and model changes, specifically asking how spatial politics have shaped the traditional scientific and technical process of map revision, appeal, and scientific review. The chapter explores the impacts to real estate, documents the alternative methodologies, and demonstrates the power of place to change risk in communities with clout. In comparison, the New York City case examines the trends of long-term sea level rise and describes the characteristics of an evolving approach to flood risk that incorporates long-term advisory maps. This is based on the thought leadership of FEMA’s Technical Mapping Advisory Council, concern about premium affordability for vulnerable households, and desire to reduce uncertainty for markets of a lagging policy process.

In the absence of a top-down federal flood risk management standard, urban planners need a bottom-up tool for long-term investment and development decisions. Cities have begun to assess their own sea level rise risk, but often via fungible models averaged out to planning scenarios that are abstracted as rules-of-thumb. The dissertation proposes a more transparent and science-based approach that addresses the information gap between short-term excessive premiums or building standards across too broad an area, and the long-term avoided losses to the city and its tax base. Furthermore, mapping as a decision support system can help planners manage the systemic impacts of NFIP rates signaling future conditions.

The academic literature has assumed that the local politics of flood risk are secondary to national-level scientific and technical knowledge. Instead, the dissertation finds that communities with clout cast controversy on flood maps to reduce the hazard area and change the models acceptable to science. As such, recent simultaneous mapping efforts and policy reforms have encouraged the fragmentation and privatization of the program. The NFIP cannot be revised through tweaking economic levers or scientific and technical appeals alone. The research here raises new value-based considerations for urban planners as they develop local and regional climate adaptation policy and planning strategies. Insurance and the ability to mitigate risk have made the modern city. Sea level rise will continue this trend far into the future, reshaping waterfronts and coastal areas across the United States and world.