Author: Papiya Barman and Nazrul Islam
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This study investigates the spatio-temporal dynamics of riverbank erosion, accretion, and land use/land cover (LULC) changes along the Raidak-II River in the flood-prone foothills of the eastern Himalayas in Alipurduar District, West Bengal, over 20 years (2003–2023). The river, shaped by intense monsoonal floods and geomorphic activity, was analyzed using multi-temporal Landsat imagery (2003, 2013, 2023) and processed through remote sensing (RS) and geographic information system (GIS) techniques. The primary objectives were to delineate zones of erosion and accretion, quantify their extent over time, and assess associated LULC transitions. The results indicate a total erosion of 6.79 km² and accretion of 28.94 km², with a net land gain of 22.15 km². Decadal analysis reveals an 80.34% reduction in erosion and a 144.09% increase in accretion between 2013 and 2023, suggesting evolving fluvial stability due to both natural and anthropogenic factors. LULC analysis revealed a sharp decline in cultivated land and a rise in settlements and riparian vegetation, highlighting land use transformation. Statistical analysis using the Friedman Test (p = 0.0054) and Dunn’s Post-Hoc Test confirmed significant differences in LULC across the years, particularly between 2003 and 2023. The study highlights the need for policy interventions in erosion-prone zones, sustainable livelihood planning, and continuous geospatial monitoring. Future research should integrate hydrological modelling and community-based management for adaptive river basin governance
Bank Erosion, Accretion, Remote Sensing, LULC Change, Statistical Analysis, Raidak-II River, Alipurduar
To sustainably manage the Raidak II River basin, an integrated river catchment approach must be adopted that balances sediment dynamics, ecological integrity, and local livelihoods. First, sediment management plans should be developed upstream—through controlled-release structures and check dams—to moderate peak flows and reduce excessive bank erosion downstream (Langat et al., 2019). Second, riparian buffer zones planted with native vegetation (e.g., Vetiver grass, bamboo) should be legally protected and expanded along vulnerable stretches (Jaydebpur, Amarpur) to stabilize banks and enhance habitat continuity. Third, land use zoning regulations must discourage settlement and high-intensity agriculture on newly accreted bars, instead designating these areas for controlled agroforestry or community forestry schemes that both generate livelihoods and maintain riparian cover. Fourth, embankment and levee construction should be paired with floodplain reconnection designs—such as gated spillways—that allow periodic inundation of accreted lands, reducing flood risk while replenishing soil fertility. Fifth, participatory monitoring and early warning systems, leveraging community observations and simple gauge stations, can help anticipate bank failure events and coordinate timely responses (Langhorst & Pavelsky 2023). Policymakers should forge cross-sectoral collaboration between irrigation, forestry, urban development, and disaster management agencies to ensure that interventions in one sector (e.g., irrigation withdrawals or bridge construction) do not inadvertently exacerbate downstream erosion or sedimentation. Over the past two decades, the Raidak II River has exhibited a net accretion of 11.08 km²—driven by decadal increases in sediment deposition and moderated erosion—resulting in the formation of new alluvial landforms and significant LULC transformations. Statistical analyses (Friedman and Dunn's tests) confirm that the most dramatic land cover changes occurred between 2003 and 2013, with stabilization thereafter. While accretion has created opportunities for agriculture, habitat regeneration, and floodplain expansion, persistent bank erosion continues to threaten riparian communities and infrastructure. The intertwined geomorphological and anthropogenic processes underscore the need for holistic, adaptive river basin management that integrates sediment control, riparian restoration, land use planning, and community engagement. Only through coordinated policy action and community collaboration can the Raidak II basin's dynamic landscape be guided toward resilience, ensuring both ecological health and socio-economic well-being for its dependent populations
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Papiya Barman and Nazrul Islam (2025). Riverbank Erosion, Accretion, and LULC Dynamics in the Raidak-II River Basin: A Geospatial Analysis in Alipurduar, West Bengal. International Journal of Theoretical & Applied Sciences, 17(2): 65–79
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