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Abstract <p>This study investigates the planform evolution of the Lower Ganga River over a 35-year period (1988–2023), emphasizing meander migration and erosion–accretion dynamics through multi-temporal Landsat imagery and GIS-based analysis. The modified Normalized Difference Water Index (mNDWI) was applied to Landsat 5, 7, and 8 datasets in Google Earth Engine (GEE) to delineate annual water bodies, enabling accurate detection of channel shifts and erosion-prone zones. Analysis across three equally divided reaches (R1, R2, R3) along the 484 km stretch of the river and vulnerable meander loops (Z1, Z2, Z3) using centreline and bank-line extraction revealed significant lateral (sideways) migration of the channel, particularly in R1 and R2, where outer bank erosion exceeded 1300 m. These shifts correspond with enhanced meander sinuosity promoted by flow curvature and helical flow structures, resulting in simultaneous outer bank erosion and inner bank deposition. In contrast, R3 exhibited minimal geomorphic change, attributed to embankments and reduced hydrodynamic variability. Structural control, assessed through digitized lineament data from the Geological Survey of India (Bhukosh), further influenced migration patterns, where drainage-parallel lineaments restricted channel mobility and stabilized banks. This integrated assessment highlights the combined influence of hydrological, geological, and anthropogenic factors on river morphology, offering insights for erosion risk zoning, flood mitigation, and sustainable river corridor management.</p> Research highlights <p><UnorderedList Mark="Bullet"> <ItemContent> <p>Provides spatio-temporal data for the meandering River.</p> </ItemContent> <ItemContent> <p>Examines the extensive dynamics of river bank changes.</p> </ItemContent> <ItemContent> <p>Finds erosion prone meander zones.</p> </ItemContent> <ItemContent> <p>Validates changes with river dynamics.</p> </ItemContent> </UnorderedList></p>

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Assessment of the planform evolution of the Lower Ganga River: Meander migration and the causative factors

  • 期刊论文

  • 发表日期：

    2025年11月28日

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  • Sagnik Jha,
  • Vikas Kumar Das,
  • Koustuv Debnath,
  • Susanta Chaudhuri,
  • Santanu Banerjee

摘要

Abstract

This study investigates the planform evolution of the Lower Ganga River over a 35-year period (1988–2023), emphasizing meander migration and erosion–accretion dynamics through multi-temporal Landsat imagery and GIS-based analysis. The modified Normalized Difference Water Index (mNDWI) was applied to Landsat 5, 7, and 8 datasets in Google Earth Engine (GEE) to delineate annual water bodies, enabling accurate detection of channel shifts and erosion-prone zones. Analysis across three equally divided reaches (R1, R2, R3) along the 484 km stretch of the river and vulnerable meander loops (Z1, Z2, Z3) using centreline and bank-line extraction revealed significant lateral (sideways) migration of the channel, particularly in R1 and R2, where outer bank erosion exceeded 1300 m. These shifts correspond with enhanced meander sinuosity promoted by flow curvature and helical flow structures, resulting in simultaneous outer bank erosion and inner bank deposition. In contrast, R3 exhibited minimal geomorphic change, attributed to embankments and reduced hydrodynamic variability. Structural control, assessed through digitized lineament data from the Geological Survey of India (Bhukosh), further influenced migration patterns, where drainage-parallel lineaments restricted channel mobility and stabilized banks. This integrated assessment highlights the combined influence of hydrological, geological, and anthropogenic factors on river morphology, offering insights for erosion risk zoning, flood mitigation, and sustainable river corridor management.

Research highlights

Provides spatio-temporal data for the meandering River.

Examines the extensive dynamics of river bank changes.

Finds erosion prone meander zones.

Validates changes with river dynamics.