Author(s): Mahesh Patel; Anurag Sharma; Bimlesh Kumar

Linked Author(s): Mahesh Patel, Anurag Sharma, Bimlesh Kumar

Keywords: Sediment transport; Bedforms; Downward seepage; Integral scales

Abstract: An experimental investigation has been carried out on a threshold curvilinear cross section alluvial channel for the no seepage and with seepage scenarios. It has been observed that Shields stress increased after extracting the water in the vertical downward direction from the channel bed. This increase in the bed shear stress caused initiation of development of bedforms. By following that a set of bed elevations profiles were measured with the help of ultrasonic ranging system at different time intervals in test section of the channel. To analyse these bed elevation profiles, a bedforms tracking tool used to obtain the variation in geometry of the bedforms. It has been observed that in the beginning the mean height of bedforms was larger at bank side compared to the centre line of the channel, although, a mean length of bedforms was shorter than the centre line geometry. However, with the passage of time, bed material from the banks was transported to feed the adjacent bedforms towards the centre line of the channel. In the end of the experiment, after 24 hour run, it was found that there were negligible changes in geometry and in Shields shear stress, indicating that the channel was about to attain regime conditions. In addition, the integral length scale and time scale were increased in the presence of downward seepage, suggested larger momentum transfer resulting in the development of larger of bedforms in the centre of the channel.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022562

Year: 2022