Study on the process of river-bed adjustment caused by clear water scouring

Based on the flume experiment of the clear water scouring at the sandy bed,the observation and analysis are carried out about the longitudinal profile adjustment,the scale of sand wave,the thickness of the bed materials armoring layer,the relationship between armoring bed materials layer and sand wave migration,the graduation of the bed materials armoring layer,bed load graduation etc.Then the mechanics of clear water souring and river-bed balance of reconstruction is revealed.The flume experiment shows that the slope of upper reaches is leveled,bed material is coarsened,sand wave is developed,bed resistance is increased,the water depth is deeper,the flow velocity is reduced with the clear water scouring.As a result the sand supply capacity of river is weakened and the sediment transport capacity is reduced,in a word,the rivers drive to equilibrium.