PROGNOSIS OF AGGRADATION IN THE LOWER YELLOW RIVER BY HISTORIC ANALYSIS OF THE MORPHOLOGY OF ITS ABANDONED ANCIENT CHANNEL

1. INTROOUCnONFor a long time, the Lower Yellow River has been aggtading. As a result, the river bed becomesmuch higher than the adjacent land beyond the levees and poses a threat to the safety of the GreatNorthern Plain of China. Since the founding of the New China, great success has been achieved insafeguarding the levee for forty years. The trend of aggravation in lower reaches however is still Soingon and is at a rate even higher than before. That makes the flood control on the LO…

PROGNOSIS OF AGGRADATION IN THE LOWER YELLOW RIVER BY HISTORIC ANALYSIS OF THE MORPHOLOGY OF ITS ABANDONED ANCIENT CHANNEL

On the basis of analyzing historical records and field data, the process in the formation of longitudinal profile of the ancient Lower Yellow River channel (1194-1855) has been studied. It is found that the process of profile adjustment can be roughly divided into two stages. In the first stage, the river channel adjusts itself by steepening its slope to match the transportation of sediment load. In the second stage, aggradation raises the profile of the entire Lower Yellow River in order to balance the retrogressive effect of the seaward extension of the river mouth. A close relationship can be set up between the profile raising and the river course extension. The profile of the present Lower Yellow River is quite similar to that of the ancient Lower Yellow River channel and has changed little in the last forty years. It is thus concluded that the present Lower Yellow River has now also undergone a second stage of profile adjustment and the seaward extension of the river has become the main cause of the on-going aggradation in the river channel. Therefore, it is of fundamental importance to reduce the sediment influx into the estuarine area if the aggradation of the present Lower Yellow River is to be mitigated.