Abstract: It has been proved by analyzing the field data that the adjustment of riverbed in alluvial river is delayed due to variations of water and sediment load. In this paper, Jianli station in Changjiang river was selected as the research object. Through analyzing process and characteristics of delayed response of the bankfull area of Jianli station, we explore the regularity of area regulation response, and establish a delayed response model, which is suitable for the regularity. The results show that, influence of incoming water and sediment of Jianli station at early period on current bankfull area’s regulation really exists, and the delayed response theory can also be used to Jianli station, located at Jingjiang segment, Changjiang river. Meanwhile, after improving the delayed response model for Yellow river, we establish the modified delayed response model of bankfull area for Jianli station.

Key words: variations of water and sediment, alluvial river, Jianli hydrological station, bankfull area, delayed response, riverbed evolution