Abstract

Base on the observed data in years from 2000 to 2006, Xiaolangdi reservoir impounding water, the regulation of erosion and deposition in reservoir area and the Lower Yellow River have been analyzed. Under persistent scouring state, the relationship between sediment carrying capacity and accumulative erosion has been quantified according to sediment transport law. It is pointed that the sediment transport capacity reducing is given rise to by inadequate supplement of fine and medium sized sediment (less than 0.05mm) within effective bed exchange layers. With reference to the observed data during the period of Sanmenxia reservoir impoundment, the sediment discharging effect through Xiaolangdi reservoir density current floods and the response in the lower river channel have been compared and studied. Xiaolangdi reservoir is provided with great potential for detaining coarse and releasing fine sediment. It is found that hyper-concentrated density current floods would not result in severe deposition in the Lower Yellow River and the deposition during the lower floods only presented its temporary regulation. Therefore, in flood regulation, the natural or artificial density current shall be fully made use so as to discharge more sediment and trap the less to realize the sedimentation reduction of the lower reaches of Yellow River for a long time.

Keywords: Xiaolangdi Reservoir, lower Yellow River, density current flood, sediment regulation, sediment transport capacity, retaining coarse sediment and releasing the fine, sedimentation reduction