How Do Changing Hurricane Rainfall Estimates Affect Pluvial Flood Risk in the Caribbean Under Current and Future Climate Change?

Abstract:

Recent record-breaking hydrometeorological disasters such as Hurricane Maria (2017) and Hurricane Dorian (2019) have reaffirmed once again the acute disaster risk facing Caribbean small island states. Heralded by many as a sign of the ‘new normal’, three important questions arise – how might extreme hurricane rainfall evolve under a changing climate, what influence would this have on flood risk, and what could this mean for the sustainable development of Caribbean islands now and in the future? Yet, although extreme hurricane rainfall is already a key cause of flooding in the Caribbean, estimates of current and future hurricane rainfall-induced pluvial flooding are limited.

Using Puerto Rico as a test case, this research aims to address these critical questions, by initially exploring how changing hurricane rainfall intensity, duration and exceedance frequency influence the flood depth and extent of pluvial flood estimates in Puerto Rico under different climate change scenarios. Firstly, an event set of 59,000 hurricane rainfall estimates for historical, 1.5°C and 2°C Paris Agreement climate projections were derived from a hurricane rainfall model (Vosper et al., 2020). Rain rate information for different durations and return periods were then used as an input to hydrodynamic model LISFLOOD-FP (Sampson et al., 2013) to simulate pluvial flood hazard at the island scale.

The results of this research will provide useful information for both the hydrology and disaster risk reduction communities regarding both the methodology of how the hurricane model and hydrodynamic model are coupled, as well as how pluvial flood risk might change under different climate change scenarios. This research will also support the continued development of risk assessment for improved disaster preparedness in Small Island Developing States – an increasingly urgent, but understudied task.

References

Sampson, C.C., Bates, P.D., Neal, J.C., Horritt, M.S., 2013. An automated routing methodology to enable direct rainfall in high resolution shallow water models. Hydrological Processes 27, 467–476.

Vosper, E.L., Mitchell, D., Emanuel, K., 2020. Extreme Hurricane Rainfall affecting the Caribbean mitigated by the Paris Agreement Goals. Environmental Research Letters In press.