黄河中游降水量特征及变化趋势分析

Analysis on Characteristic of Precipitation and Variation Tendency of the Middle Yellow Rive

根据黄河中游河龙区间、龙三区间、三花区间1956-2000年的实测月平均降水资料，利用降水不均匀系数、距平分析法、5年滑动平均法、线性倾向估计法及水文统计学方法等对降水特征及变化趋势进行了研究。结果表明：①黄河中游年均降水量为433-659mm，降水量时空分布不均匀，主要集中于6-9月，年降水量下游多于上游，年降水量Cv值为0.17-0.22，整体上降水量的年际变化上游大于下游；②1956-2000年年降水量整体处于下降趋势，其中秋季下降趋势最为显著，其次是春、冬季，夏季的变化相对较小。

The paper studies the characteristic of precipitation and variation tendency by using coefficient of non-uniformity of precipitation and the methods of anomaly analysis,5-year moving averages,linear estimation and hydrologic statistics based on the observed monthly mean precipitation data of He-Long reach,Long-San reach and San-Hua reach situated on the middle Yellow River in 1956-2000.The outcomes show that a) the annual precipitation of the middle Yellow River is 433-659 mm,uneven temporal and spatial distribution of precipitation,mainly concentrated in the period of June-September,the annual precipitation of the lower reaches is more than that of the upper reaches,CV value of annual precipitation 0.17-0.22 and the inter-annual variation of precipitation of the upper stream is greater than that of the downstream in the whole and;b) the annual precipitation in 1956-2000 is in the trend of decrease,of which,the reduction trend in autumn is the most obvious and the variation in spring,winter and summer is relatively smaller.