River Bank Erosion

Syllabus: GS1/Geography

Context

• The Brahmaputra, Teesta, and Dharla rivers have become unpredictable, eroding land faster than ever before.

About Riverbank Erosion

• Riverbank erosion is the wearing away of the banks of a river due to the continuous action of flowing water. 
• It is a natural geomorphological process but can be accelerated by human activities or environmental changes.
• When water flows along a river channel, it exerts shear stress on the riverbanks. 
  • Over time, this force removes soil, sand, and rock particles from the bank, leading to undercutting, collapse, and retreat of the riverbank.

Causes of Riverbank Erosion

• Natural Causes
  • Strong river currents: Fast-flowing water erodes the outer banks of bends (meanders).
  • Floods: High water volume and velocity during floods intensify erosion.
  • Soil composition: Loose or sandy soils erode more easily.
  • Lack of vegetation: Roots help bind the soil; their absence makes banks fragile.
  • River meandering: Continuous shifting of river channels causes lateral erosion.
• Human-Induced Causes: 
  • Deforestation near riverbanks.
  • Sand mining and gravel extraction.
  • Construction of dams and embankments altering natural flow.
  • Overgrazing or cultivation close to the river edge.

Impacts

• Loss of agricultural land and livelihoods.
• Displacement of people, which is also a major problem in states like Assam and West Bengal.
• Damage to infrastructure such as roads, bridges, and embankments.
• Sedimentation downstream, affecting navigation and aquatic life.

Control and Mitigation Measures

• Bioengineering methods: planting grasses, shrubs, and trees to stabilize banks.
• Construction of revetments, spurs, and gabion walls.
• River training and dredging to manage flow.
• Community-based riverbank management and land-use planning.

Source: TH