Sediment bank contribution to form a vortex and a deep scour hole on tidal channel meander

This dataset aims to examine the potential mechanism that generated a deep scour hole in the thalweg of a narrow tidal meander located in the Bahia Blanca estuary (Argentina). Based on bathymetric, currents, and sediment data collected through oceanographic surveys, we hypothesize that a sediment bank within the channel can modify the tidal current pattern contributing to the formation and maintenance of a deep hole in the meander curvature. Based on our data, we found that the formation and maintenance of the scour hole are possible because of a vortex forced by the presence of an elongated sandy bank connected to the tidal channel bank that acts as a barrier to the currents, inducing the modification of the typical meander current pattern. The currents curvature favoring the establishment of the scour hole in the thalweg on the north channel bank, and the presence of a countermeander causes an attenuation of the current velocities mainly during the flood. On the other hand, the present sediment characteristics at the bottom of the hole allow us to assume that the scour hole is now at a stage of dynamic equilibrium with the current conditions.

本数据集旨在探究阿根廷布兰卡湾河口一处狭窄潮汐弯道深泓线（thalweg）内形成深冲刷坑（scour hole）的潜在机制。本研究基于海洋调查获取的水深、水流及沉积物数据，提出假说：河道内的泥沙岸堤可改变潮汐流场模式，进而促成该弯道曲率处深坑的形成与维持。基于本次观测数据，研究发现该冲刷坑的形成与维持源于：与潮汐河道岸堤相连的细长沙质岸堤可阻挡水流，形成强迫涡旋，进而改变典型弯道的流场模式。水流曲率有利于在河道北岸深泓线处形成冲刷坑，而反向弯道（countermeander）的存在主要在涨潮阶段削弱了水流流速。另一方面，冲刷坑底部的现有沉积物特征表明，该冲刷坑目前已与当前水动力条件达到动态平衡状态。