Temporal and Spatial Characteristics of Scarce Precipitation in the Yellow River Basin

The temporal and spatial distribution characteristic of precipitation in the Yellow River basin were analyzed. Distribution of average annual precipitation and distribution of variation rate of annual precipitation were calculated from daily precipitation data from 1980 to 2000. The areas where the variation rate is high and an abnormal scarce precipitation is common were pointed out. The observation points whose variation rate are maximum and minimum were selected, frequency of scarce precipitation was analyzed from interannual variation of annual precipitation for the past 21 years. A scarce precipitation year was defined as the year the ratio of annual precipitation to normal is less than 0.8. The characteristic of monthly precipitation in the scarce precipitation year was analyzed, and spatial distribution of annual precipitation was shown with the ratio of annual precipitation to normal, the scarce-precipitation area and the heavy-precipitation area were shown.