Seawater intrusion in the coastal aquifers is a major concern in India. What are the causes of seawater intrusion and the remedial measures to combat this hazard? (Answer in 150 words)

Introduction

Seawater intrusion occurs when saline water replaces freshwater in coastal aquifers, usually after hydraulic gradients are disturbed.

Causes

• Excessive groundwater pumping for cities, tourism, irrigation and industry lowers the freshwater table.
• Reduced recharge from concretisation, drought and altered drainage weakens the freshwater barrier.
• Sea-level rise, storm surges and coastal erosion push saline water inland.
• Canal leakage, aquaculture and poorly managed borewells may intensify salinity.

Remedial measures

• Regulate extraction through aquifer mapping, metering, permits and community groundwater budgeting.
• Increase recharge using rainwater harvesting, recharge wells, managed aquifer recharge and wetland protection.
• Adopt micro-irrigation, treated wastewater reuse and desalination where locally viable.
• Create freshwater pumping barriers, monitor electrical conductivity and prevent well-screening errors.
• Integrate coastal-zone planning with climate adaptation.

Keywords: hydraulic gradient, over-extraction, recharge, salinity, aquifer management.