Abstract Point bars are prominent features in meandering rivers, yet our understanding of the complex interactions among the morphology of the point bars to channel planform and curvature remains incomplete. This study seeks to address the extent to which channel centerline curvature can explain point bar morphology. High-resolution elevation datasets obtained from multibeam sonar and structure-from-motion surveys are used to characterize point bar morphology on twelve point bars within two river systems; the Pearl and Wabash rivers. Spatial series of centerline curvature are compared to channel and point bar characteristics including width, migration rate, centerline longitudinal bed elevation, transverse bed slope, and a shape factor. Results show that the Wabash reach has overall lower channel curvature values and higher rates of migration compared to the Pearl reach. However, the spatial lag between curvature and width and migration rate are similar between reaches. The mode of bend migration differs between the two reaches, where the Pearl reach has bends mostly evolving through translation downstream, and along the Wabash reach, one bend is expanding, two bends are mostly stationary, and three bends are translating downstream. The translating bends in both reaches exhibit bilinear (a pronounced break in slope) and near-horizontal (a pronounced break in slope with a nearly flat bar top) transverse bar profiles and maximum rates of migration downstream of the apex. The Pearl reach has a systematic distribution of transverse bar profiles where linear profiles are found along the bar head and bar tail, and near-horizontal profiles are concentrated along the middle bar. The distribution along the bars of the Wabash reach is less systematic, with fewer near-horizontal profiles overall. Finally, to evaluate the influence of curvature on the channel bed and bar morphology, the field data are compared to synthetic bed elevation data generated using pyRiverBed, a centerline curvature-driven bed evolution model that maintains a constant width. Analyses reveal the synthetic morphologic data agree reasonably well with the characteristics and magnitude of the field observations, with a mean absolute error of 0.9 and 1.2 m for the Pearl and Wabash rivers, respectively. Values of transverse slope were also compared between the field and synthetic data and the synthetic data are consistently under-predicted along the Pearl. Differences observed between the field and synthetic data are the result of variability in the natural river system not captured by the model including channel width, the presence of local bedrock outcrops, and abrupt changes in curvature.

中文翻译：

---

点杆形态与渠道曲率和平面演化的关系

摘要 点坝是蜿蜒河流的显着特征，但我们对点坝形态与河道平面和曲率之间复杂相互作用的理解仍然不完整。本研究旨在解决通道中心线曲率可以解释点棒形态的程度。从多波束声纳和运动结构测量中获得的高分辨率高程数据集用于表征两个河流系统内十二个点坝上的点坝形态；珍珠河和瓦巴什河。将中心线曲率的空间序列与包括宽度、迁移率、中心线纵向河床高程、横向河床坡度和形状因子在内的河道和点坝特征进行比较。结果表明，与珍珠河段相比，瓦巴什河段总体上具有较低的河道曲率值和较高的迁移率。然而，曲率和宽度之间的空间滞后以及迁移率在河段之间是相似的。两条河段的弯道迁移方式不同，珍珠河段的弯道主要通过向下游平移演化，而沿瓦巴什河段，一个弯道扩张，两个弯道大部分静止，三个弯道向下游平移。两个河段的平移弯曲都表现出双线性（斜坡明显中断）和接近水平（斜坡明显中断，钢筋顶部几乎平坦）横向钢筋轮廓和顶点下游迁移的最大速率。Pearl 河段具有系统的横向钢筋剖面分布，其中沿钢筋头部和钢筋尾部发现线性剖面，并且沿中间钢筋集中了近水平剖面。沿 Wabash 河段的分布不太系统，总体上近水平剖面较少。最后，为了评估曲率对河床和坝体形态的影响，将现场数据与使用 pyRiverBed 生成的合成河床高程数据进行比较，pyRiverBed 是一种保持恒定宽度的中心线曲率驱动的河床演化模型。分析表明，合成的形态数据与实地观测的特征和幅度相当吻合，珠江和瓦巴什河的平均绝对误差分别为 0.9 和 1.2 m。还比较了实地和合成数据之间的横向坡度值，并且合成数据沿珍珠一直被低估。现场数据和合成数据之间观察到的差异是模型未捕获的天然河流系统变化的结果，包括河道宽度、局部基岩露头的存在以及曲率的突然变化。