Influence of Silt-Discharge Condition of the Lower Yellow River to the Scour and Fill of the Channel

The paper analyzes the relationship of rate of silting of the lower Yellow River channel during flood season and the runoff rate,sediment discharge,mean discharge,mean sediment concentration and coefficient of incoming sediment of Xiaolangdi Station based on the observed data of the lower channel since 1950;and further analyzes the influence of silt-discharge condition of the lower channel during a regulated discharge regime of the river to the scour and fill of the channel based on the observed data of 8 regulated discharge regimes of the Xiaolangdi Reservoir during 2002-2008 period.The outcomes show that the rate of silting of the lower channel decreases along with the increase of runoff rate or mean discharge of Xiaolangdi Station and increases along with the increase of the mean sediment concentration or coefficient of incoming sediment of Xiaolangdi Station;the lower channel is scoured in a regulated discharge regime period,the channel rate of silting increases along with the increase of incoming sediment,the average sediment concentration of reservoir outlet and the coefficient of incoming sediment and decreases along with the increase of runoff amount of reservoir outlet and flood duration and;after flood season of 2007,the controlled outlet discharge of the Xiaolangdi Reservoir is 3 600 m3/s and sediment concentration 40 kg/m3,basically achieving scour and fill balance in the lower river channel.