Characteristics of Change in Precipitation Resources in Chongqing During 1961-2006

On the basis of the monthly precipitation data from 30 weather stations in Chongqing from 1961 to 2006,the spatial and temporal characteristics of precipitation variation in Chongqing were statistically analyzed.The mean of spring,autumn,and annual precipitation in Chongqing showed a decreasing trend from 1961 to 2006,and the decrease in autumn precipitation was highly significant(r0.01).The mean of summer and winter precipitation in Chongqing exhibited a small increasing trend.Wavelet analysis showed a 15-year periodic oscillation in the 46 years for the precipitation in Chongqing.From the trend distributions,the spring and annual precipitation presented a decreasing trend in Chongqing except its northwestern part.The summer and winter precipitation presented an increasing trend except its western part.On the whole,autumn precipitation showed a decreasing trend in Chongqing,and the decrease was significant statistically in its southern part(r0.05).