ON THE SPATIAL AND TEMPORAL DISTRIBUTION OF PRECIPITATION IN THE WESTERN-ROUTE OF SOUTH-TO-NORTH WATER TRANSFER PROJECT

The precipitation data of 78 meteorological stations over the Source Region of the West-route of South-to-North Water Transfer Project from 1956 to 2001 was selected to analyse the spatial and temporal distribution using Mann-Kendall method and correlation analysis.It reviewed that: the spatial distribution of the annual precipitation depended on large terrain.The annual precipitations on eastern part of Qinhai-Tibet Plateau were less than 1 000 mm,while the annual precipitations on western part of Sichuan Basin were more than 1 000 mm,some of which were close to 2 000 mm.The annual precipitations on north western of Yungui Plateau were about 1 000 mm.The annual variation of precipitations was not generally noticeable.The annual precipitation distributions were almost the same.The rainy seasons were summer and autumn at most stations,and summer and autumn precipitation accounted for 76%~91% of the total.Precipitation slope of 55 sites was above zero,and that of the other 23 sites was below zero,and slope of 27% of the sites reached the significant level,but it did not present a strong tend generally.The altitude of the sites and the annual precipitation presented strongly negative correlation on the whole,while the situation was opposite where localized topography varied severely.