Prediction of the bankfull discharge in the lower Wei River

The main channel of the lower Wei River,the largest tributary of the Yellow River,is dramatically shrinking resulting in a markedly decrease of the bankfull discharge in recent years.A method was developed to predict the bankfull discharge at the Huaxian station of the lower Wei River.Analysis of the field data from the Huaxian station indicates that the bankfull discharge of the lower Wei River is affected not only by the incoming water and sediment load,but also by erosion base level of downstream(at the Tongguan elevation).The delayed response model includes the effects of the peak discharge,Tongguan elevation,average flow discharge and average incoming sediment coefficient for the flood season to predict bankfull discharge in the lower Wei River.Comparison shows that the method accurately describes the changes of the bankfull discharge.