Delayed response model for bankfull area of the Gaocun Station on the Lower Yellow River

Based on the concept that the rate of adjustment is proportional to the difference between the actual state and the equilibrium state of the channel,a delayed response model for bankfull area calculation at Gaocun station on the Lower Yellow River was developed.The method takes into account for the cumulative effect of previous years’flow and sediment conditions on the current year's bankfull discharge.The characteristics of delayed response of bankfull area to the flow and sediment conditions were analyzed.The results revealed that the current year's bankfull area is a result of the cumulative effect of several consecutive years'flow discharge and sediment load conditions.The cumulative effect of flow regime in the preceding years on the bankfull area is significant for the nearest 4 to 5 years,and it becomes smaller and smaller as time goes to the past.