Temporal and Spatial Variation of Characteristics of Precipitation in Songhua River Basin during 1958-2009

In order to illustrate and analyze temporal and spatial variation of characteristics of precipitation in Songhua River Basin,the precipitation data were interpolated by Kriging interpolation method.The Mann-Kendall test was applied to examine the trend of precipitation.The concentration degree and period of annual precipitation were used to analyze the annual distribution of precipitation.The results show that ∶ 1) In recent 52 years(1958—2009) the annual precipitation shows an indistinctive negative trend.The annual precipitation decreases from eastern part to western part,and most of the basin area show an indistinctive negative trend.2) The annual precipitation distribution is uneven,occurs mainly from May to September,with June to August being most abundant.The flood-season(from June to September) precipitation occupies 77.65% of the annual precipitation and shows a weak negative trend throughout the basin.3) The concentration degree of annual precipitation is very high,averaging 0.682,and the concentration degree of southeastern part is smaller than that of northwestern part.The concentration period of annual precipitation is from 181.90° to 187.68°,the annual precipitation is concentrated from 20,July to 26,July,the concentration period of northern part is longer than that of southern part.The concentration degree of annual precipitation shows an indistinctive decreasing trend,while the concentration period of annual precipitation shows a significant decreasing trend.