Evaluating the feasibility of coastal protection scenarios on a city scale across plausible pathways scenarios for both sea level rise and urban development

Abstract

Coastal flood risk accelerates rapidly due to rising sea levels and urban expansion in low-lying areas. Many strategies based on the widespread application of hard protection have been developed. However, the implementation of such measures has raised concerns due to their environmental impact, high costs, and a potential increase in exposure.

This study focuses on the economic implications of coastal flood protection at the local level, examining impacts on small to medium-sized cities, which reflects many coastal communities around the world. We introduce a framework for assessing the economic burden or benefit of flood protection strategies on local communities and municipalities. We derive standardized values for protection costs, flood risk, and socioeconomic development for typical coastal topologies, i.e., the data usually used for cost-benefit analyses of coastal protection.

Based on two illustrative examples of coastal cities in different topographies, we demonstrate that cost-effective protection strategies can lead to lock-in situations because their implementation cost likely exceeds local willingness to pay, and we argue that this risk needs to be considered when designing flood adaptation pathways.