1950-2015年黄河下游河道排洪输沙时空演变

基于1950—2015年长序列的水沙数据，以平滩流量作为漫滩洪水的参照值，通过时间序列分析和统计分析，研究了黄河下游不同河段的排洪和输沙能力。结果表明:黄河下游的基本排洪能力在空间上具有相似性，不同河段的排洪能力随时间变化具有比较好的一致性；排洪能力随时间变化表现为阶段性减小，与上中游来水的丰枯具有密切关系，并部分受到水库调节的影响，尤其是小浪底水库在水沙调控中的作用。并对比分析了1950—2015年日平均流量大于平滩流量的发生情况，发现漫滩洪水的发生频率是逐渐减小的，输送的水量与小于漫滩流量输送的水量相比也是逐渐减少的。输沙能力在空间上具有一定差异，高村以上的游荡河段在20世纪后期都是逐渐减小的，21世纪初期的输沙能力逐渐提高，高村以下河段在研究期内的输沙能力变化较小，艾山—洛口河段基本不变，孙口—艾山河段和洛口—利津河段在1998年以前的变化不大，之后前者略有提升，后者略有减弱。研究期内黄河的排洪输沙能力总体上是减弱的，虽然现今水沙量显著减少，但河道的淤积升高仍然给排洪输沙带来很大的压力，提高黄河下游整个河道的排洪输沙能力依然是河道治理的关键所在。

Temporal and Spatial Variation of Flood-Conveying and Sediment-Transporting Capacity of the Lower Reaches of the Yellow River During 1950-2015

Based on data measured during 1950—2015, the flood-conveying and sediment-transporting capacities were studied by methods of time series analysis and statistical analysis. Analyses showed that, flood-conveying capacities of different sub-reaches of the lower reaches of Yellow River (LYR) were similar. The variances of capacities with time in different sub-reaches were almost constant. The flood-conveying capacity decreased in different stages, and it was closely related to discharge hydrographs from the upper and middle drainage areas. It may also be partially influenced by reservoir regulation, especially the Xiaolangdi Reservoir during water-sediment regulation. For sediment-transporting capacity, capacity of the wandering sub-reach (upper Gaocun) decreased during 1995—2000, and then it showed the increasing trend after 2000. However, the sediment-transporting capacity of the sub-reach downstream Gaocun was almost constant before 1998. After 1998, capacity of Aishan-Luokou sub-reach increased with limited magnitude, and the value for Sunkou-Aishan sub-reach decreased with limited magnitude. In total, the flood-conveying and sediment-transporting capacities decreased. Despite the decreased water runoff and sediment load, deposition in the lower channel made delivering flood and sediment through the channel worse. It indicates that enlarging the capacities of flood-conveying and sediment-transporting is the key aspect of channel regulation in the LYR.