Mutual adjustment between process and form shapes the morphology of alluvial river channels, including channel banks. The tops of banks define the transition between the channel and adjacent floodplain, which corresponds to the level of incipient flooding. Despite the geomorphological and hydrological importance of this transition, few, if any, studies have extensively examined spatial variability in bank elevations and its influence on bankfull stage. This study uses an objective method to explore this variability at two spatial resolutions along three alluvial lowland meandering rivers. Results show that variability in bankfull stage is inherent to all three rivers. The mean variability of bankfull stage about the average downstream gradient in this stage is 10% to 20% of mean bankfull depth. Elevations of channel banks exhibit similar variability, even after accounting for systematic variations in heights of inner and outer banks associated with river meandering. Two‐dimensional hydraulic simulations show that the elevation range of mean variability in bankfull stage overlaps considerably with the elevation range of high curvature on rating curves, confirming that variability in bankfull stage influences the shape of these curves. The simulations verify that breaks in channel banks allow flow to extend onto the floodplain at stages below the average bankfull stage. The findings provide fundamental insight into the variable nature of bankfull conditions along meandering rivers and the role of this variability in channel‐floodplain connectivity. The results also inform river‐restoration efforts that seek to re‐establish the natural configuration of channel banks.

中文翻译：

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低地蜿蜒河流河岸期和河岸高程的空间变异性：与等级曲线和航道平面特征的关系

过程和形态之间的相互调整塑造了冲积河道的形态，包括河道岸。堤岸顶部定义了河道与邻近洪泛区之间的过渡，这与初期洪泛的程度相对应。尽管这一过渡的地貌和水文重要性，但很少有研究（如果有的话）广泛地研究了河岸高程的空间变异性及其对河岸丰满期的影响。这项研究使用一种客观的方法来研究沿三个冲积低地蜿蜒河流的两种空间分辨率下的这种变异性。结果表明，全部三个河段均具有河岸丰满期的变异性。大约在该阶段平均下游坡度的河床满期的平均变异性是平均河床满深度的10％至20％。即使考虑了与河流蜿蜒相关的内，外河岸高度的系统变化，河道高程也表现出相似的变化性。二维水力模拟表明，堤岸阶段平均变化的高程范围与额定曲线上高曲率的高程范围有相当大的重叠，这证实了堤岸阶段的平均变化会影响这些曲线的形状。该模拟验证了河岸堤的破裂允许流量在平均堤岸满水位以下的水位扩展到洪泛区。这些发现提供了基本的洞察力，可以了解蜿蜒河流沿岸的满员条件的可变性以及这种变化在河道-洪泛区连通性中的作用。