Morphological Dynamics of Mid-Channel Bars under Controlled River Regime.

The study on evolutionary dynamics of Mid-Channel Bars (MCBs) under regulated-river regime is surprisingly scanty. To bridging this gap, morphological variables of 32 MCBs and channel parameters of a reach of ∼75.83 km of Bhagirathi-Hooghly River were examined over a time span of 30 years. For quantifying MCBs dimensions, satellite imageries and Google earth pro images were used under GIS environment. Bivariate-Correlation and Variability in MCB parameters were assessed using goodness-of-fit measures (R²) and CV or σ respectively. It is found that over time, the number and area of MCBs has been increased 3.56 times from 9 in 1990 to 32 in 2023. The reach of the river is on the way of transformation form meandering one to the braiding one. Both frequency of MCBs and braiding intensity show an increasing trend towards downstream. It is found that there was more than 1 MCBs within a wavelength in 2023 and it was much less in 1990 (0.3).The temporal variability in size of MCBs shows that smaller MCBs are more variable than larger one. Stability of larger MCBs are attributedto the impact of permanently grown vegetation. Dynamics in MCBs shape do not show any significant spatio-temporal trend. The larger MCBs are more circular than smaller ones attributing to the lateral accumulation of sediments under vegetated MCB margins. This work suggests that continued investigation into the MCB dynamics is to be substantiated by more advanced technology-based interdisciplinary approaches based on robust data. [ABSTRACT FROM AUTHOR]