by Eahya Al Huda*, Hiraxmi Deb Barma, Ngawang Drema Trangpoder, Parbin Nahar Begum, Abhijit Saikia, Dulumoni Basumatary, Tage Rupa Sora
ABSTRACT
The Lower Dikrong River catchment, a tributary of the Brahmaputra in northeastern India, is subject to intense fluvial dynamics, resulting in significant bankline migration and land degradation. This study employs remote sensing and Geographic Information System (GIS) techniques to quantify and analyze the spatiotemporal patterns of bankline shifting along the Lower Dikrong River in Lakhimpur district, Assam, over a 31-year period (1988–2019). Multi-temporal satellite data from Landsat 5 (MSS and TM sensors) and Landsat 8 (OLI/TIRS) were acquired and processed to extract riverbank positions for the years 1988, 1998, 2001, 2009 and 2019. Eleven cross-sections were established perpendicular to the river’s thalweg to measure lateral displacement using the Digital Shoreline Analysis System (DSAS) in ArcGIS. The results indicate that the river has undergone substantial bankline shifts, with maximum erosion reaching up to 2,897.45 m on the left bank between 1988 and 1998 (C14). The highest cumulative erosion was observed on the right bank between 1998 and 2009 (1,378.08 m at C7), while the period 2009–2019 demonstrated localized but persistent erosion, particularly on the left bank (e.g., 617.08 m at C9). The shifting pattern reveals a dominance of left bank erosion in the upper reaches and right-bank dominance in the middle to lower reaches, influenced by sinuosity, geology and anthropogenic interference. Seasonal flooding, sediment load and river curvature play critical roles in bank instability. This study provides a scientific basis for riverbank management and flood risk mitigation in one of Assam’s most vulnerable regions. The integration of remote sensing with GIS offers an effective, low-cost methodology for long-term monitoring of dynamic river systems.
