水沙变化条件下黄河下游游荡性河段河势变化特性

根据实测资料分析，总结分析了黄河下游1986年以来水沙变化的主要特点，进而着重对水沙变化后黄河下游游荡性河道河势调整的新特点进行了阐述。其特点主要是：主流摆动幅度减弱，支汉、心滩减少；河道弯曲程度增加，河湾个数增多；工程靠溜部位上提下挫现象增多，工程上首塌滩严重；畸形河湾增加；工程脱河和半脱河现象较为严重；小水易出险等。从而认识到，水沙变化后，河势变化更加复杂。应深入探讨河势调整的机理，并通过小浪底水库调水调沙来减弱水沙变化程度，同时，在一些河势调整剧烈的河段修建能够适应长期中小水河势调整的整治工程是改善不利河势的有效途径。

Changes in the wandering reach of the lower Yellow River due to changes in flow and sediment regimes

Based on the measured date, the paper summaries the changes in the regimes of flow and sediment coming to the lower Yellow River after 1986, and it expounds the changes in the wandering part of the lower Yellow River due to the changes in flow and sediment regimes, which are characterized by small amplitudes of main course shifting, less anabranches and shoals, increases in both channel curvature and channel bends,more occurrences of flow touching the training structures in upper parts, more severe sliding at the heads of the river training structures, and more occurrences of abnormal bends, more training structures disfunctioning completely or partly, more failures of the training structures and more flooding by low flow etc. The complicated changes highlight the necessities of studying the mechanism of the channel adjustment, reducing the changes in flow and sediment by regulating flow and sediment with the Xiaolangdi Reservoir, and building more training structures suitable for middle and low flow.