Reasonable Arranging of Spare Channel to lowering the Speed of the Estuary Extension

摘要

A great quantity of sediment, transported to the estuarial area of the Yellow River every year, has made the estuary in the evolution of sedimentation, extension, twisting and divagation for a long time. In the course of "small circle" and "big circle" evolution at the delta, sediment settled down, the delta level rose, the sand bar at the outfall successively extended to the sea, and the water level of the estuarial reach under the same discharge was raised, resulting in the sedimentation on the river reach above the estuary and continuous transferring to the upstream, which would affect the safety against flood. In case of the realignment of the estuarial channel, its length distinctly shortened to cause retrogressive scour and lowering of water level under the identical discharge, which is favorable for the safety of flood control. The estuarial and coastal areas are the major regions where the sediment running into the estuary is disposed. During the period from 1950 to 1985, only 33% sediment carried to the estuarial area was transferred to the sea and the remaining 67% was deposited on the delta and its upstream. In order to keep the long term stability of the Yellow River, it is essential to rationally arrange spare river channels, to make full use of vast area outside the delta, and to maintain the seashore line as long as possible for outer sedimentation so that the extension pace of the estuarial channel can be slowed down. At present, Diaokouhe, Maxinhe and Shibabu channels shall be regarded as the spares, in addition, the administrative scope shall be defined.