中文摘要：

小浪底水库运行后,黄河下游游荡段河床冲刷剧烈,滩岸崩退过程较为显著。估算典型断面的滩岸崩退过程,不仅有助于全面掌握该河段的河床演变规律,同时也能为河道整治及规划等提供相关参数。以1999—2013年游荡段典型断面（水文断面及淤积断面）汛后实测地形资料为基础,确定了这些断面平滩河宽的调整过程,发现多年平均崩退速率最大达215 m/a;分析了影响滩岸崩退过程的不同因素,发现滩岸土体组成及力学特性、滩槽高差等因素虽对崩退过程有一定影响,但来水来沙条件是主要影响因素;分别建立了游荡段水文断面及淤积断面滩岸累计崩退宽度与前期5年平均汛期水流冲刷强度之间的经验关系,相关系数都在0.85以上。公式计算值与实测值吻合较好,可用来估算游荡段典型断面滩岸的崩退过程。

英文摘要：

The braided reach of the Lower Yellow River （LYR） is experiencing severe channel degradation, and significant bank retreat processes have occurred owing to the operation of the Xiaolangdi reservoir. Estimation of bank retreat processes at typical sections can not only help to understand the characteristics of fluvial processes, but also offer parameters relevant to river regulation and planning. In this study, the variation in bankfull Widths at typical sections of the braided reach has been investigated based on the observed cross-sectional profiles during the period from 1999 to 2013, with the maximum multi-year average bank retreat rate of 215 mfa being obtained. Several factors influencing bank retreat have been presented, which reveals that the composition and mechanical properties of the bank soil, and the elevation difference between floodplain and main channel can influence the processes of bank retreat, but the in- coming flow and sediment regime is the dominant factor in controlling bank erosion. Empirical relationships between the accumulated bank retreat width and the previous 5-year average fluvial erosion intensity were developed at typical hydrometric sections and sedimentation sections, with the minimum correlation coefficients of above 0.85. Therefore, the calculated processes of bank retreat agree well with the measurements at these typical sections, and the proposed empirical relations can be used to estimate bank retreat processes in the braided reach of the LYR.