百年尺度黄河上中游水沙变化趋势分析

根据黄河有实测资料以来的水文泥沙定位观测数据,利用非线性统计方法分析了1919—2012年黄河潼关以上河段水沙系列变化趋势。20世纪80年代中期以来水沙变化特点表明,黄河年径流量、年输沙量自20世纪80年代中期以来总体呈不断减少之趋势,而上中游水沙关系则早于20世纪60年代末已发生突变,1986年发生的突变属上中游同时发生的第2次突变。从百年尺度看,黄河水沙变化在1960年以前主要受到气候等自然因素影响,径流泥沙系列随降雨丰歉而出现相应的丰枯变化,之后黄河水沙变化受气候等自然因素和人类活动因素的双重影响,尽管不同时段降雨有丰歉变化,但径流量、输沙量都持续减少;近百年内年输沙量趋势度的绝对值明显大于年径流量趋势度的绝对值,中游的年径流量、年输沙量的趋势度的绝对值明显大于上游的;近30年是黄河水沙百年尺度中最枯的时段,其变化的突出特点表现在来水来沙量不断显著减少,水沙变化程度在空间上分布不均,泥沙主要减于中游而径流主要减于上游,水沙年内分配趋于均匀,来沙系数趋于降低,水沙搭配关系趋好。

Analysis of trend of runoff and sediment load in upper and middle reaches of Yellow River at century scale

According to observed data of runoff and sediment load in the Yellow River from 1919 to 2012, the trend of the runoff and sediment load in the reaches upstream of Tongguan was analyzed with nonlinear statistical methods. The annual runoff and sediment discharge has shown a declining trend in the Yellow River since the mid-1980s, and the relationship between runoff and the sediment load in the upper and middle reaches of the Yellow River abruptly changed before the late 1960s and abruptly changed again in 1986. At the century scale, the runoff and sediment changes of the Yellow River were mainly influenced by climatic and other natural factors before 1960, high and low runoff and sediment loads occurred with changes in rainfall, while the runoff and sediment changes were influenced by human activities and natural factors since 1960. Though rainfall showed significant changes at different times, the runoff and sediment load decreased continuously. Over the last hundred years, the absolute value of the tendency of the annual sediment transport amount has been significantly higher than that of the annual runoff, and the absolute values of the tendency of annual runoff and the sediment transport amount in the middle reach have been significantly higher than those in the upper reach. Over the last 30 years, the runoff and sediment load were at their lowest levels in the Yellow River, and the outstanding characteristics were the continuous decrease of the runoff and sediment load, the uneven spatial distribution of the runoff and sediment load, the decrease of the sediment load mainly occurring in the middle reaches, and the decrease of runoff mainly occurring in the upper reaches. Thus, the annual distribution of the runoff and sediment load tended to be uniform, the incoming sediment coefficient tended to decrease, and the relation between runoff and sediment load tended to be strong.