Syllabus: Infrastructure
Source: TH
Context: India faces an ageing dam challenge — over 1,065 dams are 50–100 years old and 224 are 100+ years old (2023 data).
- Experts warn that many dams are nearing the end of their design life, raising safety, irrigation, and hydropower
About Ageing Dams in India:
History of Dams in India:
- Pre-Independence: Kallanai (2nd century CE) is one of the world’s oldest functioning dams, built for irrigation; Mettur (1934) and Nizam Sagar (1931) were among the earliest large modern reservoirs.
- Colonial Era: British built Krishna and Godavari anicuts to boost canal irrigation; conceptualised Damodar Valley Corporation on the Tennessee Valley model.
- Post-Independence Era: Bhakra-Nangal (1963), Hirakud (1957), Rihand, Tungabhadra and Koyna dams symbolised Nehru’s “temples of modern India,” fueling Green Revolution.
- 1951–1971 Expansion: India started work on 418 large dams in two decades, marking a massive nation-building push for irrigation, power, and flood control.
- Modern Era: Shift to multipurpose projects integrating irrigation, power, tourism, navigation, and inland fisheries for holistic water resource development.
- Current Phase: Focus on rehabilitation, modernization, and climate resilience to extend lifespan and ensure safety of ageing infrastructure.
Laws & Policies for Dams in India:
- Dam Safety Act, 2021: Provides a legal framework for dam surveillance, operation, and maintenance; establishes NDSA, National Committee on Dam Safety, and State Dam Safety Organisations (SDSOs).
- Mandatory Inspections: Requires pre- and post-monsoon inspections, Emergency Action Plans, and inundation maps to prevent disasters and ensure preparedness.
- Dam Rehabilitation and Improvement Project (DRIP I–III): Covers 736 dams across 19 States with World Bank & AIIB funding for structural strengthening, gate replacement, monitoring equipment, and staff training.
- Central Water Commission (CWC) Guidelines: Issue technical protocols for periodic safety reviews, risk assessment, and remedial action to maintain dam health.
- No Formal Decommissioning Policy: India currently focuses on extending lifespan; lacks a structured framework to safely retire obsolete or unsafe dams.
Challenges to Dams in India:
- Ageing Infrastructure:
- Over 4,200 dams will cross the 50-year mark by 2050, raising risks of structural fatigue and safety lapses.
- Old spillway designs are inadequate to handle present-day floods, increasing overtopping risk.
- Sedimentation & Loss of Capacity:
- Bhakra, Hirakud, and Lower Bhavani lost 20–30% storage due to siltation.
- Reduced live storage hits irrigation potential, hydro generation, and drinking water supply.
- Climate Change & Extreme Events:
- Cloudbursts, GLOFs (Sikkim 2023), and intense monsoons strain ageing dams.
- Flood routing capacities often lag behind probable maximum flood estimates.
- Seismic & Geotechnical Risks:
- Dams like Mullaperiyar & Koyna lie in seismically active zones; cracks & seepage are recurring concerns.
- Foundation erosion and piping threaten earth-fill dams’ stability.
- Institutional & Governance Gaps:
- Inadequate data transparency and limited citizen participation.
- Absence of decommissioning policy and slow implementation of rehabilitation projects.
Case Studies:
- Mullaperiyar Dam (1895): 120+ years old, inter-state safety dispute between Kerala & TN, seismic vulnerability flagged by experts.
- Hirakud Dam (1957): Lost 25% capacity and near-overtopping in 1982 prompted auxiliary spillway creation.
- Bhakra Nangal (1963): Sedimentation reduced reservoir capacity by 23%; seismic reanalysis underway.
- Tiware Dam Failure (2019): Breach killed 19 people and highlighted need for robust inspection regime.
Way Forward:
- Risk-Based Prioritisation
- Focus on high-consequence dams first (downstream population, economic value).
- Independent third-party safety audits.
- Strengthening Infrastructure
- Retrofit spillways, reinforce structures per latest seismic & climate standards.
- Catchment area treatment to slow silt inflow.
- Decommissioning & Repurposing
- Develop formal policy for safe decommissioning when risk > benefit.
- Explore alternate water storage systems (aquifer recharge, check dams).
- Community Engagement & Transparency
- Downstream hazard mapping, public warning systems, mock drills.
- Open-access dam safety database for citizen oversight.
- Climate-Resilient Design
- Incorporate probable maximum flood (PMF), GLOF risk, glacial retreat modelling in dam management plans.
Conclusion:
India’s dams are both lifelines and liabilities as they age. A science-based, risk-informed, and climate-resilient approach to dam management is vital. Long-term sustainability lies not just in preserving dams, but in prioritizing safety, minimizing risks, and ensuring intergenerational water security.
