2002年以来黄河下游河道冲淤时空演变

Temporal and spatial processes of scour and deposition in the Lower Yellow River since 2002

小浪底水库以下具有较完整水位、流量、含沙量记录的水文站有8个。通过分析这些水文站2002年之后的水位和流量数据,发现同流量条件下水位随时间增加而减小。花园口实测河道大断面面积随时间增加而增大,平均水深加深。对比花园口水文站水位流量及其实测断面随时间的变化,认为二者反映了相同的物理意义,同流量条件下水位随时间减小说明河道发生冲刷。进一步分析各水文站的来沙系数,发现河流的冲刷或淤积与来沙系数有关。在时间上,小浪底以下各水文站来沙系数持续减小;在空间上,黄河下游各水文站来沙系数沿程增加。如果决定河流冲淤的来沙系数阈值是0.01,那么花园口至利津河段,均为下切区域;淤积区域应该在小浪底和花园口之间,该规律已经被白鹤和铁谢实测断面所证实。

Eight hydrologic stations were constructed in the Lower Yellow River after the operation of Xiaolang- di reservoir after 2002 , which record water-level, discharge and sediment concentration in detail. Hydrologic data show that water-level turns to be lower in the same discharge with time. Processes of observed riverbed profiles at Huayuankou is detected. The area of cross section under the same water-level turned to larger with time, and the average depths of river were deeper. It is believed that the data, obtained from both hydrometric stations and observed riverbed profiles, showed that the river channel was scoured after the operation of Xia- olangdi Reservoir. Analysis shows that down scour on the channel is determined by the incoming sediment co-efficient. The income sediment coefficients at all the hydrometric stations turned to smaller with time, and turned to bigger in space from Xiaolangdi Station to Lijin Station. If the threshold of incoming sediment coeffi-cient for river to cut down is 0.01 , then the deposit area is between Huayuankou and Xiaolangdi hydrometric stations. The other areas of river channel turn to be down cutting. These results have been confirmed by two cross-sectional profiles.