Channel Pattern Morphology of the Bhagirathi Hooghly River Using GIS Techniques

River channel morphology ranges from simple single-thread channels to highly complex multi-thread systems, reflecting the interplay of hydrological and sedimentary processes. The Bhagirathi–Hooghly River exhibits considerable planform variability along its course, with pronounced meandering and localised braiding. This study employs remote sensing and Geographic Information System (GIS) techniques to analyse channel morphology and planform dynamics. OpenStreetMap (OSM) base maps and SWORD shapefiles were integrated within the WGS-84 projection framework to ensure spatial accuracy. The ~ 486.52 km river stretch, extending from Murshidabad district to the Bay of Bengal, was divided into eight reaches for detailed investigation. The analysis incorporates multiple geomorphological indices, including the Braiding Index (Brice, 1964), Sinuosity Index (Schumm, 1963), Planform Index (Sharma, 2004), Sensitivity Index, and Active Channel Width following Kuo (2017). The results indicate a Braiding Index of 0.82, suggesting moderate braiding, while the Sinuosity Index of 1.50 reflects a well-developed meandering pattern. The Planform Index value of 1.23 further confirms significant channel complexity. A high Sensitivity Index (5.83) and a very large Active Channel Width (161,663.32 m) reveal that the river is highly dynamic and responsive to hydrological and sedimentary variations. Spatial analysis shows that bar and island development is most extensive in the lower reaches, whereas the middle reaches contain numerous but relatively smaller geomorphic features. Overall, the findings suggest that the river exhibits a mixed planform dominated by meandering with localised braided characteristics, controlled by both natural processes and anthropogenic influences. This study demonstrates the effectiveness of integrated remote sensing and GIS techniques in quantitatively assessing river morphology, planform dynamics, and channel stability.