Evaluation of drought occurrence and climate change in the Pearl River Basin in south China

Abstract

Exploration of droughts caused by climate change would be highly valuable in sustaining agriculture and civilization. In this study, the 55 datasets of climate projection from 18 General Circulation Models (GCMs) for the IPCC AR4 (SRES A2/A1B/B1) and AR5 (RCP 2.6/4.5/6.0/8.5) are used. Then, the monthly Standardized Precipitation Index (SPI) is generated to detect the drought occurrence. The study area is the Pearl River basin in South China. This study validates the GCMs projection through comparing the observed precipitation over the study area for the period of 2001-2013. Then, the spatial variations of the frequency change of moderate drought, severe drought and extreme drought are analyzed for the 21st century. Moreover, coefficients of variance (CV) of precipitation are calculated to detect the effect of Indian monsoon on drought in the Pearl River basin in South China. The study reveals that the frequencies of moderate drought and extreme drought occurrences over the Pearl River basin would be more severe for the first half of the 21st century than the second half. Specifically, for the high emission scenarios, the east and west regions of the Pearl River basin most likely suffer from moderate drought and severe drought with an increased frequency throughout the whole 21st century. The uncertainty of all 18 GCMs and 55 scenarios shows that the drought situation is eased for the second half than the first half in the 21st century. From the SPI comparison between emission scenarios in AR4 and AR5, uncertainty results are almost similar. SPI comparison of distinguished emission scenarios reveals that the dry or wet conditions are not necessarily related with high or low emission scenarios. Moreover, the first half of the 21st century should be noticed for dry conditions.