中文摘要：

针对荆江河段内河道形态和河床组成空间差异性均较大的沙卵石～沙质河床过渡河段，采用三峡水库蓄水以来的实测水沙、地形资料，分析了沿程不同区间内河道调整特性，探讨了不同河床调整方式对枯水位降落的影响，结果表明：沙卵石～沙质河床过渡特性在河床调整方式上也有所体现，昌门溪以上河床冲刷以侧蚀为主要方式，放宽段侧蚀程度大于束窄段，枯水河槽断面趋于宽浅化；昌门溪以下河床冲刷以深蚀为主要方式，各水位下河槽断面均趋于窄深化，变形方式的差异是不同区间内主流摆幅和河床抗冲性综合作用的结果。侧蚀冲刷引起的不同流量下枯水位降幅不均匀程度大于深蚀冲刷。以昌门溪为界，针对不同变形方式，防护措施应有所区别。

英文摘要：

By using the hydrologic, morphological and geological observations in the Yangtze reach from Zhicheng to Dabujie, cross-section deformation and its spatial variations are examined and responses of water level to this deformation are investigated. The inconsistency in cross-section adjustment in different regions is revealed. In the upper reach, lateral erosion is the major deformation and erosion intensity is greater in an expanding section than contracting section, causing the channel wider and shallower at low level. In the lower reach, down-cut erosion dominates the deformation at all the water levels and the channel develops toward the opposite, narrower and deeper. The difference of the two reaches in dominant deformation is a result of the comprehensive effect of different mainstream swings and riverbed materials. Water level drop caused by erosion under different discharges, is uneven in magnitude over the whole reach, greater in the sections of lateral erosion than vertical erosion. Thus, Changrnenxi is a location of deformation transition from lateral erosion to down-cut erosion and the protective measures should be distinguished.