Spatiotemporal Analysis of Riverbank Erosion, Accretion, and Channel Shifting of the Bukhainagar River (1990–2020) Using geospatial Technique in Southern Bangladesh

Riverbank erosion, accretion, and channel shifting are critical geomorphological processes that shape the dynamics of rivers and surrounding landscapes, particularly in the region like southern Bangladesh. This study investigates the spatiotemporal dynamics of these processes along the Bukhainagar River from 1990 to 2020 using Geographic Information System (GIS) and Remote Sensing (RS) techniques. Landsat satellite imagery and supervised classification were employed to analyze changes in the river morphology over the 30-year period, with a focus on identifying erosion and accretion patterns. The study also incorporates Focus Group Discussions (FGDs) with local communities to assess both the geomorphological changes and socio-economic. The results from satellite imagery revealed significant erosion and accretion dynamics, with maximum erosion rates of 21.88 hectares per year (ha/year) from 2010–2020 and highest accretion rates of 10.31 ha/year. Overall, the net land loss over the 30 years was 177.12 ha, with an average annual erosion rate of 10.5 ha/year and an average accretion rate of 4.6 ha/year. These oscillations reflect the meandering patterns river course over time, particularly evident in the lower and middle sections. The FGDs emphasized the socio-economic impacts of these changes, such as displacement, loss of agricultural land, and economic distress owing to erosion. The findings highlight the urgent need for integrated river management strategies that combine scientific data with indigenous knowledge to address these dynamic alterations and mitigate the detrimental impacts on livelihoods and ecosystems. This study contributes to the growing body of research on river dynamics in Bangladesh, demonstrating the effectiveness of GIS and RS techniques in monitoring long-term river changes, and provides important implications for sustainable river management and climate change adaptation strategies in deltaic regions.