长江沙市段断面面积对水沙变异的滞后响应研究

通过长江中游沙市站的实测水沙、断面资料的分析表明,沙市站河槽形态的调整对水沙变异存在一定滞后性。为了研究沙市河段河床演变的滞后响应规律,从3个方面对适用于黄河流域的河床演变滞后响应模型进行改进:①以沙市站多年平均枯水位下的断面面积作为滞后响应模型的特征变量;②引入“年组合流量”概念;③在模型迭代公式中使用分段函数,从而得到适用于沙市河段的河床演变滞后响应模型。利用模型迭代公式进行计算,结果表明改进后的河床演变滞后响应模型计算精度R²处于0.7~0.8之间,可以很好地描述沙市站河槽形态的调整规律。

Delayed Response of Cross Section Area to Variable Incoming Flow and Sediment at Shashi Segment of Yangtze River

Analysis on the measured flow and sediment data of the middle reaches of the Yangtze River as well as the section data indicates that the adjustment of channel morphology at Shashi station is delayed to the variation of flow and sediment conditions. In order to obtain the regularity of delayed response of Shashi section, we improved the delayed response model for river evolution in the Yellow River in three aspects: 1) define the cross section area at the annual average low water level of Shashi section as the characteristic variable of the delayed response model; 2) introduce the “yearly combined flow” ;3) use the piecewise function in the iterative formula of the model. The results show that the determinant coefficient R² of delayed response model for river evolution at Shashi section is between 0.7 and 0.8.