Analysis on Sediment Delivery Ratio of Regulated Discharge Regime of the Xiaolangdi Reservoir in 2008-2009 Period

The paper analyzes the reasons of great difference of sediment delivery ratio occurred during regulated discharge regime before flood season of 2008 and 2009 of the Xiaolangdi Reservoir from two aspects of silt-discharge process of the reservoir inflow and the morphology of sedimentation.The outcomes show that a) the incoming sediment during flood season after 2008 is not much,the longitudinal slope of upper section of deposited sandbar is small and resistance to scour is greater,causing the initial power of artificial density current created in 2009 is smaller than that of in 2008 and;b) during the regulated discharge regime period conducted in 2009,the reservoir inflow is small,sustained period is short and follow-up power of density current is seriously insufficient after the formation of density current.Under the existing conditions,it suggests to comprehensively consider the benefits of sediment reduction of Sanmenxia and Xiaolangdi,scientifically regulate the discharging process of Sanmenxia Reservoir,rationally allocate the water for density current and subsequent delivery of the Xiaolangdi Reservoir and build Guxian Key Water Control Project as soon as possible.