关键词: 西江流域, 降水, 时空分布, 降水集中度, 降水集中期

Abstract: Based on the 1970-2017 daily precipitation data at 37 meteorological stations over the Xijiang River basin, temporal and spatial characteristics of the precipitation in this basin are analyzed using the moving average method, Mann-Kendall trend test, Sen's slope, wavelet transform, and empirical orthogonal function. Results indicate that the annual precipitation in the basin showed an insignificant decreasing trend, with a dominant cycle of 29 years, and a spatial distribution featured with a decreasing trend from east to west and north to south. In a year, most of the precipitation was concentrated in summer, and the winter season contributed the smallest proportion. It showed a decreasing trend in spring and autumn while an increasing trend in summer and winter, but the trend was significant only in spring. The precipitation was the greatest in June and showed small values of insignificant variations over the period of December to February. The precipitation concentration degree (PCD) was generally considerable large. The spatial distributions of PCD and precipitation concentration period (PCP) decreased from west to east, but their first and second modal coefficients did not show consistent or anisotropic feature in spatial distribution probably owing to the diversified causes of precipitation.

Key words: Xijiang River basin, precipitation, temporal and spatial distribution, precipitation concentration degree, precipitation concentration period