Why in news?
More than a thousand large dams in India will be over 50 years old by 2025, and several hundred are already beyond their design life. Ageing infrastructure, extreme weather and increasing sedimentation raise safety and performance concerns, prompting calls for rehabilitation and decommissioning policies.
Historical evolution of dam building in India
- Early dams: The Kallanai (Grand Anicut) on the Cauvery River, built in the 2nd century CE, is one of the world’s oldest operational dams. The Mettur Dam (1934) and Nizam Sagar (1931) were among the first modern multipurpose reservoirs.
- Colonial initiatives: British engineers constructed anicuts on the Krishna and Godavari rivers and envisioned the Damodar Valley Corporation on the Tennessee Valley model.
- Post‑Independence projects: Major dams like Bhakra‑Nangal, Hirakud, Rihand and Tungabhadra were built to provide irrigation, hydropower and flood control; Jawaharlal Nehru called them “temples of modern India.”
- Expansion era (1951–1971): Work began on hundreds of large dams, dramatically expanding irrigated area and electricity generation.
- Modern focus: New projects integrate irrigation, hydropower, tourism and even inland navigation. Rehabilitation and climate resilience are now priorities.
Laws and policies
- Dam Safety Act 2021: Establishes a National Dam Safety Authority (NDSA) and State Dam Safety Organisations (SDSOs), mandates periodic inspections and empowers authorities to set safety standards.
- DRIP projects: The Dam Rehabilitation and Improvement Project (Phases I–III) supported by the World Bank and Asian Infrastructure Investment Bank funds safety improvements for over 700 dams.
- Guidelines and gaps: The Central Water Commission recommends comprehensive safety reviews every 5–10 years. India lacks a formal policy for decommissioning or repurposing obsolete dams.
Key challenges
- Ageing structures: Over 1,000 dams are between 50 and 100 years old, and more than 200 exceed 100 years. By 2050, around 4,200 dams will cross the 50‑year mark. Many older dams were not designed for today’s extreme floods.
- Siltation: Reservoirs like Bhakra, Hirakud and Lower Bhavani have lost 20–30 % of their storage due to sediment build‑up, reducing water supply and flood cushion.
- Climate change: Increasingly erratic rainfall, glacial lake outburst floods and cloudbursts stress ageing dams and spillways.
- Seismic and structural risks: Dams such as Mullaperiyar (1895) lie in seismic zones and have developed cracks. Heavy inflows have nearly overtopped some dams in the past.
- Governance gaps: Limited public data on dam health, lack of emergency action plans and absence of decommissioning guidelines hinder risk management.
Case studies
- Mullaperiyar Dam: Located in Kerala and operated by Tamil Nadu, this 1895 dam has been subject to interstate disputes and concerns over seismic safety. Engineers have suggested lowering the water level to mitigate risk.
- Hirakud Dam: Asia’s longest earthen dam (1957) has lost nearly a quarter of its storage due to siltation. In 1982, the reservoir almost overtopped, underscoring the need for updated flood manuals.
- Bhakra-Nangal Dam: Commissioned in 1963, it has lost about 23 % capacity. Upgrading gates and spillways is essential to handle extreme inflow events.
- Tiware Dam failure: In 2019, the Tiware dam in Maharashtra breached after heavy rain, killing 19 people. Investigations revealed poor maintenance and ignored warnings, highlighting the consequences of neglect.
Way forward
- Risk-based prioritisation: Rank dams based on hazard potential and allocate funds for rehabilitation accordingly. Critical dams should undergo immediate safety audits.
- Strengthen infrastructure: Retrofit spillways, reinforce foundations, install advanced instrumentation and desilt reservoirs. Treat upstream catchments with soil conservation measures to reduce sediment inflow.
- Decommissioning and repurposing: Develop guidelines to retire unsafe or redundant dams, converting them into wetlands or check dams. Engage affected communities in decision‑making.
- Community engagement and transparency: Share dam safety information publicly, conduct mock drills and establish early warning systems for downstream residents.
- Climate-resilient design: Update design parameters based on projected rainfall and seismic scenarios. Integrate disaster management plans with reservoir operations.
- Institutional reforms: Empower the NDSA and SDSOs with adequate staff and resources. Use remote sensing, drones and IoT sensors to monitor structural health.
- Comprehensive flood management: Revise reservoir operating rules to balance irrigation, hydropower and flood control. Develop watershed-level flood forecasting and early warning systems.
Conclusion
India’s dams have served as engines of development, but many now need urgent attention. A mix of rehabilitation, prudent decommissioning, technological monitoring and community engagement is vital to ensure safety and resilience in the face of climate change.