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?
Approach · directive: “what”
What it asks · Explain why and how seawater moves into India’s coastal aquifers, and suggest engineering, management and regulatory remedies.
The question has 2 parts — answer each
- Explain the causes of seawater intrusion into India's coastal aquifers
- Suggest remedial measures — engineering, demand management, nature-based and regulatory — to combat the hazard
Open with · Seawater intrusion is the landward movement of saline water into freshwater aquifers when the natural seaward flow of groundwater weakens.
Cover
- Over-pumping for irrigation, industry and cities lowers the water table and reverses the hydraulic gradient (Saurashtra coast, Minjur near Chennai, Vasai–Virar).
- Reduced recharge: paved urban surfaces, erratic monsoon, and dams that cut river flows to deltas.
- Sea-level rise, storm surges and cyclones flood low-lying coasts; tides push saline water up creeks and estuaries.
- Land use: aquaculture ponds, salt pans, sand mining, dredging and loss of mangroves and dunes.
- Impacts: saline drinking water, soil salinity and falling yields, health stress and out-migration from coastal villages.
- Engineering remedies: tidal regulators and bandharas, check dams, recharge wells, subsurface barriers, managed aquifer recharge.
- Management: regulate extraction (CGWA), aquifer mapping, micro-irrigation, mangrove and dune restoration, a coastal monitoring-well network.
Close with · Coastal aquifers must be managed as a shared resource — balancing extraction with recharge and restoring natural buffers — before salinisation becomes irreversible.
Add value (verified)
- CGWB studies of the Mangrol–Chorwad coast of Saurashtra found salinity ingress in groundwater and linked it to local geology, coastal depressions and tidal flooding. PIB, Ministry of Jal Shakti — Salinity in Coastal Areas (21 March 2022) ↗“The presence of salinity in ground water along coastal Gujarat may be due to various reasons viz. prevailing hydro-geological settings, presence of physiographic depression in the coastal areas, inundation of sea water in low lying areas due to tidal fluctuation”
Question: UPSC's CS (Main) 2025, GS Paper III — paper ↗. Approach: Minimalist IAS, checked 30 Sept 2026 (how we verify) — UPSC publishes no model answers. ·
Model answer · 220 words (UPSC limit 150) · Minimalist IAS
Seawater intrusion is the landward movement of saline water into freshwater aquifers when the natural seaward flow of groundwater weakens, leaving wells brackish and soils salty.
Causes
- Over-pumping for irrigation, industry and cities lowers the water table and reverses the hydraulic gradient — the Saurashtra coast, Minjur near Chennai, Vasai–Virar.
- Reduced recharge: paved urban surfaces, erratic monsoons and dams that cut river flows to deltas.
- Sea-level rise, storm surges and cyclones flood low-lying coasts; tides push saline water up creeks and estuaries.
- Land use: aquaculture ponds, salt pans, sand mining, dredging and the loss of mangroves and dunes; CGWB studies of the Saurashtra coast link salinity to local geology, coastal depressions and tidal flooding.
- Impacts: saline drinking water, soil salinity and falling yields, health stress and out-migration from coastal villages.
Remedial measures
- Engineering: tidal regulators and bandharas, check dams, recharge wells and shafts, subsurface barriers and managed aquifer recharge.
- Demand management: regulate extraction through the CGWA, meter and price bulk use, micro-irrigation and salt-tolerant crops.
- Nature-based: restore mangroves, dunes and coastal wetlands as buffers against surges and tides.
- Monitoring and governance: aquifer mapping, a coastal network of monitoring wells, and coastal-zone rules that curb unsafe land use.
Coastal aquifers must be managed as a shared resource — balancing extraction with recharge and restoring natural buffers — before salinisation becomes irreversible.
Written by Minimalist IAS from facts checked at source (how we verify) — a little fuller than exam length, so every part of the question is covered; in the hall, keep the structure and trim the detail. UPSC publishes no model answers: compare your structure and coverage with this, then write your own.