SHRINKAGE ON RIVERBED FORM OF THE TAIL OF YELLOW RIVER MOUTH IN QINGSHUIGOU COURSE

Based on related characteristics of the tail of the Yellow River mouth, shrinkage on riverbed form was analyzed with channel transect form and riverbed longitudinal profile morphology. The latter includes the average elevation of main channel bed, riverbed longitudinal degradation and bank-full discharge. In the course of 1976 to 2000, there were four stages for growth of the tail of the Yellow River mouth in Qingshuigou Course, i.e. earlier growth stage, medium-term molding stage, later shrinkage stage and last development stage under artificial interference. Corresponding with above four stages, the rate of width and depth of main channels of the tail of the River mouth increases, horizontal degradation rises, riverbed longitudinal degradation descends, and average riverbed elevation uplifts. And bank-full discharge is correspondingly low during corresponding stages. These phenomena are related with dried water and sediment discharge. River dredging, artificial diversion of river course and water and silt regulation can restrain shrinkage on riverbed form of the tail of the Yellow River mouth, but it is temporary and cannot change the total tendency of riverbed shrinkage.