CHANGES IN EXTREME RAINFALL EVENTS AND THEIR INFLUENCE ON FLOOD RISK UNDER A CHANGING CLIMATE

Abstract

The changes in extreme precipitation patterns due to climate change are of concern, given the potential for increases in flood hazards and hydrologic vulnerability. In this study, historical extreme rainfall characteristics and future projections of changing one-day probable maximum precipitation (PMP) over Indian region have been studied. Historical precipitation records (1971-2010) were compared with future climate projections for the 2071-2100 period, considering both RCP4.5 and RCP8.5 scenarios. Precipitation variability and intensification were evaluated using descriptive statistical analysis, spatial classification, and multiple model comparisons. Historical PMP showed large geographical variation with an average of 720.77 mm. Mean PMP increases of 31.46% and 41.01% were projected under RCP4.5 and RCP8.5, respectively, and maximum increases of 235.97% and 281.27% under RCP4.5 and RCP8.5, respectively. Spatial analysis showed significant spatial variation and climate-model comparisons showed variation in the magnitude of projected precipitation. The results indicate that the impact of climate change on extreme precipitation and related flood risks in India may become more severe with increasing greenhouse-gas emissions. But additional hydrological and vulnerability data are needed for flood-risk quantification to be done directly. The findings from the study emphasize the need for regional flood preparedness, infrastructure planning and adaptation strategies to consider the impacts of climate projections.