Understanding morphological and hydrological changes in the Dhaleshwari River basin through remote sensing and GIS-based analysis

The Dhaleshwari River, a major distributary of the Jamuna River in central Bangladesh, has experienced substantial morphological, hydrological, and land-use changes over the past three decades. This study integrates morphometric analysis, bankline dynamics, long-term hydrological records, and LULC-spectral index modelling to evaluate the river's evolving behaviour. The basin exhibits a mature geomorphic structure characterized by a dendritic drainage network, low form factor (0.11), low elongation ratio (0.37), moderate drainage density (1.64 km/km²), and a hypsometric integral of 0.51, indicating balanced erosional-depositional processes within an elongated and relatively stable basin. Despite this structural stability, the river corridor remains highly dynamic. Between 1990 and 2020, channel length increased from 85.7 km to 111.9 km, with maximum lateral migration of 626.55 m and cumulative erosion of 12.17 km², particularly in Delduar and Manikganj Sadar. Hydrological analysis reveals strong seasonal variability and a long-term decline in peak discharge from over 1100 m³/s to approximately 800 m³/s, likely reducing sediment transport and increasing bank vulnerability. Land-use change further intensified instability through the conversion of vegetation and waterbodies into cropland and impervious surfaces. Overall, hydrological stresses and human activities drive channel adjustments, emphasizing integrated management and erosion monitoring for river resilience.