CLIMATE CHANGE IMPACTS ON HEAVY PRECIPITATION AND URBAN FLOODING

Abstract

 Recent studies report that ongoing climate change has enhanced frequency and amount of heavy precipitation, however, current design storms rely on statistics derived from long-term observed precipitation without considering the effect of climate change. In this study, we investigated how the design storms and associated maximum inundation depth and extent may change under 4-degree warmer climate condition using a large ensemble climate experiment d4PDF over the Zenpukuji river in Tokyo, which is a typical urban river basin. Daily precipitation of 20-year return period increased 1.2 times higher under 4-degree climate. Simulations of a flood analysis model using the obtained design storms showed that that maximum inundation depth and inundation extent increased up to 1.2 times and 1.5 times, respectively. We also showed that simulations using a centralized shape of design storm produced inundation extent about 10% larger than that using design storm based on scaling method.