Assessing the influence of an extended hurricane season on inland flooding potential in the Southeast United States

Abstract

Abstract. Recent tropical cyclones, like Hurricane Katrina, have been some of the worst the United States has experienced. Tropical cyclones are expected to intensify, bringing about 20 % more precipitation, in the near future in response to global climate warming. Further, global climate warming may extend the hurricane season. This study focuses on four major river basins (Neches, Pearl, Mobile, and Roanoke) in the Southeast United States that are frequently impacted by tropical cyclones. An analysis of the timing of tropical cyclones that impact these river basins found that most occur during the low discharge season, and thus rarely produce riverine flooding conditions. However, an extension of the current hurricane season of June–November, due to global climate warming, could encroach upon the high discharge seasons in these basins, increasing the susceptibility for riverine hurricane-induced flooding. This analysis shows that an extension of the hurricane season to May–December (just 2 months longer) increased the number of days that would be at risk to flooding were the average tropical cyclone to occur by 37–258 %, depending on the timing of the hurricane season in relation to the high discharge seasons on these rivers. Future research should aim to extend this analysis to all river basins in the United States that are impacted by tropical cyclones in order to provide a bigger picture of which areas are likely to experience the worst increases in flooding risk due to a probable extension of the hurricane season with expected global climate change in the near future.