A sensitivity study of rising compound coastal inundation over large flood plains in a changing climate.

Coastal flood hazards and damage to coastal communities are increasing steeply and nonlinearly due to the compound impact of intensifying tropical cyclones (TCs) and accelerating sea-level rise (SLR). We expand the probabilistic coastal flood hazard analysis framework to facilitate coastal adaptation by simulating the compound impact of predicted intensifying TCs and rising sea levels in the twenty-first century. We compared the characteristics of landfalling TCs in Florida (FL) and southwest Florida (SWFL) for the late twentieth and twenty-first centuries predicted by several climate models and downscaling models. TCs predicted by four climate models, one without downscaling and three with downscaling, were used by a coupled surge-wave model to predict the future flood hazard due to compound effects of TCs and SLR over a large SWFL coastal flood plain. By 2100, the coastal inundation metrics of the 1% annual chance coastal flood could become almost 3-7 folds of their current values, depending on the climate and downscaling models, Representative Concentration Pathway scenarios, Atlantic Multi-decadal Oscillation phases, TCs, SLR, precipitation, and how TCs and SLR are incorporated. By 2100, the current 1% (100-year) inundation event could become a 3-year event, and the 0.2% (500-year) inundation event could become a 5-year event.