Department of Geography, Gauhati University, Guwahati, Assam, India.
Department of Ecology, Environment and Remote Sensing, Government of Jammu and Kashmir, Kashmir, India.
PLoS One. 2022 Jul 20;17(7):e0271190. doi: 10.1371/journal.pone.0271190. eCollection 2022.
A common phenomenon associated with alluvial rivers is their meander evolution, eventually forming cutoffs. Point bar deposits and ox-bow lakes are the products of lateral bend migration and meander cutoff. The present study focuses on identifying the meanders of River Manu and their cutoffs. Moreover, this study compares the temporal evolution and predicts the progress of selected meanders of River Manu. In the present research, the Survey of India topographical map, satellite imagery, and geographic information system (GIS) technique were used to examine the evolution of the Manu River meander. Subsequently, a field visit was done to the selected cutoffs and meanders of River Manu to ascertain the present status and collect data. It has been observed that many cutoffs have undergone temporal changes, and their sizes have decreased. Some have become dried or converted to agricultural fields. The width of River Manu has decreased in all the selected bends from 1932 to 2017. The sinuosity index has changed from 2.04 (1932) to 1.90 (2017), and the length of the river has decreased by 7 km in 85 years (1932-2017). The decrease in length is evident from lowering the number of meanders. Uniformity coefficient and coefficient of curvature of the bank soil samples were calculated, indicating that the soil is poorly graded and falls under the cohesionless category. Based on cross-section analysis, sediment discharge, grain-size analysis of the bank material, channel planform change, and radius of curvature, it can be stated that almost all the selected bends have the probability of future cutoff. The highest probabilities were observed in bend 3 (Jalai) and bend 4 (Chhontail). This work is aimed to provide planners with decisions regarding the construction of roads and bridges in areas that show the huge dynamicity of river meandering.
冲积河流的一个常见现象是其蜿蜒演变，最终形成截弯取直。点坝沉积物和牛轭湖是侧向弯曲迁移和弯道截弯取直的产物。本研究旨在确定马努河的弯道及其截弯取直的位置。此外，本研究还比较了这些弯道的时间演变，并预测了马努河一些选定弯道的发展进程。在本研究中，利用印度测量局的地形地图、卫星图像和地理信息系统（GIS）技术来研究马努河弯道的演变。随后，对马努河的选定截弯取直点和弯道进行了实地考察，以确定其现状并收集数据。结果表明，许多截弯取直点发生了时间变化，其尺寸减小。一些已经干涸或变成了农田。从 1932 年到 2017 年，马努河所有选定弯道的宽度都减小了。从 1932 年的 2.04 变为 2017 年的 1.90，85 年内河流长度减少了 7 公里。从弯道数量减少可以明显看出长度的减少。计算了弯道两岸土壤样本的均匀系数和曲率系数，表明土壤颗粒不均匀，属于无粘性土。根据横断面分析、泥沙排放量、河岸材料的粒度分析、河道平面形态变化和曲率半径，可以得出结论，几乎所有选定的弯道都有未来截弯取直的可能性。在弯道 3（Jalai）和弯道 4（Chhontail）观察到的可能性最高。这项工作旨在为规划者提供有关在显示河流蜿蜒巨大动态性的区域建设道路和桥梁的决策依据。
