Damage Assessment from Storm Surge to Coastal Cities: Lessons from the Miami Area

Abstract

Coastal cities are growing at a very rapid pace, both in population and in terms of assets; therefore, flood risk is likely to increase substantially in these areas in the absence of specific protections. In addition, great uncertainty surrounds the future evolution of hurricane intensity and sea level rise. The area of Miami represents a clear hotspot of human and economic coastal flood exposure: there are more than 5 million inhabitants in the Miami metropolitan area and the population is growing. It is also a low-lying city with most of the population living below an elevation of 10m and is located in a region where tropical cyclones hit frequently. The present study is focused on the two contiguous counties of Miami, Dade and Broward. In this analysis, we consider the impact of different storm surges predicted by the computerized model SLOSH1 and investigate flood risks with current sea level, considering different hurricane parameters (storm category and direction, wind speed, and tide level). For each impact, we apply a damage function and determine if the considered storm surges potentially lead to asset loss, considering both properties and their contents.The results show that, in absence of protections, losses will be very high for large storm surges reaching up to tens of billions USD. In the second part of the analysis, we demonstrate how the economic impact changes when protections are built up, considering different dams’ heights. We conclude that raising flood defences would be beneficial, since the consequences of a storm surge could be enormous.