The characteristics of precipitation variation of Weihe River Basin in Shaanxi Province during recent 50 years

Based on the precipitation data of 21 stations in Weihe River Basin in Shaanxi Province in the recent 50 years(1951～2005),and using Cumulative departure curve method and signal/noise radio method,the temporal-spatial change characteristics of precipitation over the region are analyzed.The results indicate:(1) With the lowering of altitude,the precipitation is rising from west to east in the Weihe River basin,and the range of increase is approximately 15.1 mm on average for each 100-meter lowering of altitude;(2) Since the 1960s,the average annual precipitation has assumed a drop tendency in the Weihe River,with about 2 mm on average for each decade;(3) There was no mutation year in the change of precipitation in the Weihe River Basin during the 50 years,but 1982 and 2003 seemed as transition years.