黄河在调水调沙影响下的入海泥沙通量和粒度的变化趋势

基于1950-2013年的黄河水文泥沙资料,系统研究了黄河实施调水调沙以来入海泥沙在通量、粒度组成和时间分布上的变化特征,揭示了调水调沙影响下黄河入海泥沙的变化趋势。在2002年黄河实施调水调沙以来,6-11月平缓均衡的持续性高水沙量取代了调水调沙之前7-10月峰值尖瘦的汛期特征,汛期与非汛期差异减小,入海水沙通量的季节性特征显著改变。随着调水调沙的逐年实施,河床泥沙颗粒粗化,临界起动功率不断增大,而调水调沙期间的径流量峰值基本稳定,径流对下游河床冲刷效率不断降低,导致入海泥沙通量持续降低、泥沙颗粒变细。可以预见,黄河河口的淤积将会大大减缓,入海的泥沙将更多地沉积在远离河口的区域,维持河口三角洲叶瓣冲淤平衡的临界泥沙量将会加大。

VARIATION IN SEDIMENT LOAD AND GRAIN-SIZE UNDER THE INFLUENCE OF WATER AND SEDIMENT REGULATION SCHEME (WSRS) OF THE HUANGHE (YELLOW) RIVER

Based on the data of hydrology and sediment from 1950-2013, the variation of the Huanghe sediment under the influence of the Water and Sediment Regulation Scheme (WSRS) is investigated. The result indicates that, after the WSRS, the flow regime is characterized by a stable and constant high level of water and sediment discharge from June to November. The regime before the WSRS, which was characterized by a sharp peak from July to October, disappeared. It means that the seasonal characteristics are noticeably changed under the influence of the WSRS. Along with the implementations of WSRS, the river bed sediments in the lower reaches are increasingly coarser than ever, resulting in the continuous increase in the critical energy for sediment resuspension. During the period of WSRS, however, the peak value of water discharge remains constant, the erosion rate in the lower reaches slows down. The direct result for this variation is that the annual sediment load from the Huanghe to the sea gradually decreases together with the decreasing grain size. Thus, the accretion rate outside the Huanghe estuarine mouth will decrease and the critical sediment discharge to maintain the equilibrium of the active Huanghe delta lobe will increase in the coming years.