Spatio-Temporal Assessment of Channel Morpho-dynamics of the Kaljani River in the Eastern Himalayan Foothills of West Bengal Using Field-Based Cross-Sectional Surveys and Multi-Temporal Satellite Data
DOI:
https://doi.org/10.31305/rrijm.2026.v11.n04.022Keywords:
Kaljani River, channel morphology, braiding index, sinuosity index, sandbar dynamicsAbstract
This study investigates the spatio-temporal changes in channel morphology of the Kaljani River, a Himalayan foothill-fed alluvial river in northern West Bengal, India. A 98 km river stretch was analysed by integrating field-based cross-sectional surveys from 2022, 2023, and 2024 with multi-temporal satellite imagery for 1973, 1991, and 2023. The study evaluated longitudinal profile, channel width, mean and maximum depth, width-depth ratio, cross-sectional area, velocity, discharge, braiding index, sinuosity index, and sandbar dynamics to understand reach-wise morphological adjustment. Results show that the river profile declines from about 119 m in the upstream section to nearly 45 m downstream, indicating a progressive reduction in channel gradient. The upper reach is characterized by a wide, shallow, sediment-rich channel, with maximum width of about 642 m at Chuapara and width-depth ratios exceeding 550. In contrast, the downstream reach becomes narrower and deeper, with maximum depth reaching 5.725 m at Bhelakopa Pratham Khanda in 2023. Planform analysis indicates intensified braiding in the upper reach, where the braiding index increased from 0.84 in 1973 to 2.66 in 2023, accompanied by a rise in sandbar number from 26 to 133. Sinuosity is more prominent in the lower reaches, particularly Reach 4, where the index reached about 1.83 in 2023. Overall, the Kaljani River shows a transition from an aggradation-dominated, braided upstream reach to a deeper, more confined, and locally sinuous downstream reach, with implications for flood conveyance, sediment management, bank stability, and river corridor planning.
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