关键词: 不同河型段, 河道响应, 洪水过程, 黄河上游, 内蒙古河段

Abstract:

The sedimentation on channel bed in the Neimenggu (Inner Mongolia) reach of the upper Yellow River has been relative severe since the last two decades. Some of researchers expect that artificial flood can erode the channel bed and lower the channel bed. In this work, the discharge-water level hydrographs of the maximal floods that occurred in the typical years have been revealed, and the shapes of the hydrographs include single line, clockwise loop, anticlockwise loop, and complex line plus anticlockwise loop, anticlockwise loop plus line, “8”-shape plus line, nested anticlockwise loop and cross lines. These relations can reflect whether the channel bed is eroded or deposited, when eroded or deposited, and whether the erosion and deposition are iterative. The responses of the Neimenggu channel of the upper Yellow River are different from those at the downstreams. The downward erosion and the depressed channel bed have a braiding channel pattern, the evident upward aggradation has a meandering pattern, and the slight upward aggradation or the balanced erosion-deposition has a straight pattern. This trend is adaptive to the stream power decrease downstreams. The decrease of concentration of suspended sediment downstream is the evidence. Artificial flood can not change the sedimentation trend on the meandering channel bed and can not help people to inhabit in the Hetao plain to avoid the flood hazard.

Key words: channel response, different channel pattern reaches, flood processes, Neimenggu reach, upper Yellow River