长江武汉河段平滩及枯水河槽形态近期调整的机理研究

依据实测水沙及地形资料,分析了长江武汉河段近期平滩及枯水河槽形态的调整特点,确定了其与来水来沙及河床边界条件等因素之间的相关关系.三峡工程运用后,进入武汉河段的沙量大幅度减小(汉口站年均沙量仅为1.03亿t/a),河床冲刷较为显著,2001-2016年该河段平滩河槽累计冲刷量近1亿m3.平滩及枯水河槽形态参数计算表明:...

Study on the mechanism of recent channel adjustment during bankfull and low-water in the Wuhan reach of the Yangtze River

To study the characteristics and influence factors of recent channel adjustments in the Wuhan reach of the Yangtze River,bankfull and low-water channel dimensions at both section-scale and reach-scale were studied annually from 2003 to 2016. Empirical relationships were proposed between bankfull channel dimensions and influencing factors. Results show that the sediment load entering the Wuhan reach was significantly reduced after the TGP operation,with a annual average sediment discharge of 103 million t/a at the Hankou Hydrometric Station. A remarkable process of channel degradation occurred in the reach,with a cumulative volume of bed scour about 1. 0×10⁸ m³ under the bankfull level. Calculations of bankfull and low-water channel dimensions indicate that the reach-scale bankfull depth increased by about 1. 8 m,and the bankfull width remained unchanged during the period 2003-2016,with a relative bankfull area increase by 8%,which caused a narrow and deep cross-sectional geometry. The reduction degree of low water levels in the Wuhan reach accorded with the scour magnitude in the low-water channel geometry,with an insignificant variation in low-water channel geometry. The width-depth ratio under the low water level reduced gradually in recent years,which generally improved the conditions of navigation channel. Various factors influencing the adjustments in the bankfull channel geometry of the Wuhan reach were analyzed to found that the reach-scale bankfull depth and area correlated with the previous five-year average fluvial scour intensity during flood seasons,with a correlative coefficient of 0. 95.