Seawater intrusion in the coastal aquifers is a major concern in India. What are the causes of seawater intrusion and the…

Seawater intrusion is the landward migration of saline water into freshwater coastal aquifers, degrading water quality and threatening coastal ecosystems, as seen along the Saurashtra and Kutch coasts of Gujarat, around Minjur near Chennai and in parts of coastal Odisha.

Causes of Intrusion

• Natural Causes: Sea level rise driven by climate change, tidal effects, storm surges during cyclones, and reduced freshwater discharge from rivers that lowers downstream hydraulic pressure.
• Anthropogenic Causes: Excessive groundwater extraction for agriculture and industry, diminished natural recharge caused by rapid urbanization, and the deforestation of protective mangroves along coastlines.

Remedial Measures

• Physical Barriers: Constructing subsurface dams, installing freshwater injection wells to create hydraulic ridges, trenching with impermeable materials, and tidal regulators and bandharas such as those built under Gujarat's Salinity Ingress Prevention programme.
• Management Measures: Regulated groundwater abstraction, scaling up artificial recharge structures, mandatory rainwater harvesting, and intensive coastal aquifer monitoring.
• Policy Interventions: Strict enforcement of Coastal Regulation Zone (CRZ) norms, achieving National Water Mission objectives, and instituting community-based coastal aquifer management.

Integrating structural engineering with participatory governance ensures sustainable groundwater management in India's vulnerable coastal belts.