Spatiotemporal characteristics of precipitation changes in the Pearl River Basin, China

The change structures of precipitation and precipitation intensity and rainy days are analyzed for the Pearl River Basin (from 1959 to 2009) on the basis of a suite of 24 climatic indices derived from daily precipitation data at 62 meteorological stations with the help of the Mann-Kendall test. Contributions of seasonal precipitation and precipitation intensity class to the annual precipitation are also examined using the inverse distance weighted method. The following four conclusions can be drawn: (1) although the average annual precipitation of the entire basin does not show obvious variation, the number of annual rainy days has decreased significantly in 98.3 % of the stations. These two factors result in an obvious increase in precipitation intensity at 64.5 % of the stations. (2) No clear change trend has been found for seasonal precipitation over the entire area; however, the number of rainy days in each season has decreased significantly. In particular, the number of rainy days in the entire year and in the fall season has decreased in 98.3 and 100 % of the stations, respectively. (3) Although the number of rainy days in drizzle has decreased in 83.9 % of the stations, the number of rainy days where heavy rain and extremely heavy rain occurred increased in nearly 75.8 and 82.3 % of the stations, respectively. (4) The number of rainy days in fall and winter contributes more to the change in the number of annual rainy days than the number of rainy days in spring and summer. Heavy rain and extremely heavy rain contribute more to the change in total annual precipitation than drizzle; however, they contribute less to the change in the number of annual rainy days than drizzle. The findings in this study can provide important information for formulating water resource and eco-environment management strategies in the Pearl River Basin to policymakers and stakeholders.