Understanding riverbank erosion through the Lens of Turbulence: A review

The loss of land due to riverbank erosion is a crucial factor in shaping landforms and plays a significant role in fluvial geomorphology. Understanding and the quantification of the movement and the initiation of sediment particles are the key elements in various engineering and environmental studies. The entrainment and the transportation of sediment particles are controlled by many different physical processes in the sediment water interface. Among such processes, the characteristics of turbulence and the associated coherent structures within the flow are of utmost importance. Riverbank erosion is one of the major natural disasters and an issue of major concern. Flow turbulence plays an important role in riverbank erosion and in the shaping of the river planform. Eddies are pivotal in turbulence generation that sustain the random velocity fluctuations and continually distribute energy and exchange momentum through the eddy breakdown process, a feature absent in laminar flow. In this review paper a precise articulation of the characterization of turbulence parameters on riverbank erosion mechanism is presented together with different available river turbulence measurement techniques that are in use. Further, the investigations that explored the bank erosion process mechanisms both on natural riverbanks as well as in laboratory flumes in context of turbulence has also been discussed. Key insights include the impact of varying turbulence intensities on erosion rates, and the effectiveness of different turbulence parameters in the characterization of bank erosion. The review also identifies the gaps in the existing methodologies, emphasizing the need for standardizing the available techniques to enable cross-comparisons among studies. This paper provides a comprehensive summary of current measurement techniques for turbulence in riverbank regions, offering recommendations for future research and contributing valuable insights to the broader understanding of sediment transport and riverbank dynamics. Additionally, the discussion also outlines potential directions for future developments. This review paper in indented to discuss the characterisation of the turbulence parameters at the near bank region.