Assessment of Climate Change Impacts on Urban Rainfall Extremes for Achieving Sustainable Urban Water Development in Hanoi, Vietnam

Abstract

In recent decades, the increased frequency of disaster events, particularly hydro-meteorological disasters, have threatened human lives and infrastructure. In the context of climate change, urban water management became more complicated because of erratic or heavy rain events or prolonged droughts. Now, sustainable water management and planning requires to visualize the potential impact of climate change on extreme rainfall pattern in order to reduce the climatic vulnerability. This chapter evaluates the impact of climate change on extreme rainfall intensities under different greenhouse gases emission RCP (Representative Concentration Paths) considering future period of 2070-2099 over a baseline period of 1976-2005. The impacts were assessed using rainfall output of 5 General Circulation Models (GCM) under RCP 8.5 (high) and RCP 4.5 (medium) emission scenarios. Bilinear interpolation and quantile mapping technique were applied to extract rainfall data from grid points onto station points and to correct bias of GCM simulations in comparison with the observational data respectively. To derive the rainfall IDF (Intensity-Duration-Frequency) curves, daily rainfall output was temporally downscaled using scaling method. In the study, IDF curves were developed and the performances of the downscaling method were evaluated. The results indicate that the mean of corrected monthly rainfall and the frequency of wet days are considerably closer to observation than the raw rainfall estimates. In addition, the bias correction method accurately captured extreme rainfall values for all 5 GCM and indicated that by the end of the century, under different scenarios the rainfall intensity is increasing for all the durations and the return periods. The results will assist the water manager and urban planner to design the sustainable and robust water infrastructure.