Precipitation variability (1956-2002) in the Dongjiang River (Zhujiang River basin, China) and associated large-scale circulation

摘要

Monthly precipitation data covering 1956-2002 at 36 rain stations are analyzed to explore the spatio-temporal variability of the seasonal precipitation in the Dongjiang River basin, south China, using a continuous wavelet transform method, Mann-Kendall trend test, and simple regressive technique. The results indicated that: (1) increasing precipitation is observed in spring and winter; while decreasing precipitation is identified in summer and autumn. The increasing/decreasing precipitation trend mostly occurred near the lower/upper parts of the Dongjiang River basin; (2) the spatial distribution of the precipitation anomaly between 1956-1989 and 1990-2002 is similar to that of precipitation trend; (3) in general, 4 time periods are identified: 1956-1961 and 1975-1985 are featured by increasing areal average annual precipitation; while 1962-1974 and 1986-2002 are characterized by decreasing areal average annual precipitation. The areal average annual maximum precipitation has a decreasing trend; (4) the precipitation changes in the Dongjiang River basin are mainly controlled by the south-east Asian monsoon activities. Intensity of the south-east Asian monsoon carrying excess moisture is the main driving factor for precipitation changes in this study. This result will be greatly helpful for further research on availability and management of the water resources in the Dongjiang River basin, the main focus of an on-going research project.