Overview:

India boasts 4,407 large dams, ranking third globally, following China (23,841) and the USA (9,263). The nation faces significant challenges in safeguarding these structures, especially as many dams are aging, surpassing the 25-year mark, with over 80% of them being more than a quarter-century old. By 2025, more than 1,000 dams will have reached or exceeded the 50-year milestone.

Key Threats to Indian Dams:

Ageing Infrastructure:

• A considerable portion of India's dams, over 6,000 in number, are showing signs of wear and tear, with 234 dams having endured over a century. The need to ensure the safety of these aging structures is paramount.

Sediment Accumulation and Siltation:

• Sediment buildup in reservoirs reduces their capacity over time, impacting their longevity. Siltation, caused by the accumulation of silt and debris behind dams, further diminishes storage capacity.

Structural Challenges:

• Many of India's dams are earthen, constructed by compacting layers of earth rather than concrete, making them susceptible to deterioration as they age.

Flooding Vulnerability:

• India experiences concentrated rainfall within specific periods, making dams vulnerable to floods. Flood-related incidents have accounted for 44% of dam failures in the country, posing a significant risk to downstream areas.

Seismic Risks:

• Himalayan dam systems, such as the Tehri Dam, are located in active seismic zones due to the constant geological changes in the Himalayan mountain system, making them susceptible to tectonic movements.

Addressing these challenges is crucial to maintaining the integrity and safety of India's extensive dam infrastructure.

Dam Safety Act (DSA), 2021: Safeguarding India's Dams

Overview:

The Dam Safety Act (DSA), enacted in 2021, is a comprehensive legislation designed to ensure the surveillance, inspection, operation, and maintenance of specified dams. Its primary objective is to prevent dam failure-related disasters. The Act covers dams with a height exceeding 15 meters or those with a height between 10 to 15 meters, subject to specific design and structural conditions.

Key Provisions and Significance:

The DSA outlines two categories of offenses related to dam safety and emphasizes regular risk assessments, reflecting India's proactive approach to safeguarding its aging dams. The Act mandates the establishment of essential bodies, including the National Committee on Dam Safety (NCDS) and the National Dam Safety Authority, responsible for policy evolution, technical assistance, and conflict resolution between dam safety organizations.

Roles and Responsibilities:

Under the DSA, dam owners are required to establish dedicated Dam Safety Units, prepare Emergency Action Plans, and conduct Comprehensive Safety Evaluations at regular intervals. The Chairman of the Central Water Commission (CWC) oversees national-level dam safety protocols. At the state level, the Act mandates the formation of State Committee on Dam Safety and State Dam Safety Organisation, responsible for surveillance, inspection, monitoring, and emergency preparedness within their jurisdictions.

State Obligations:

States are obligated to classify dams based on hazard risk, conduct routine inspections, develop emergency action plans, establish flood warning systems, conduct safety reviews, periodic risk assessments, and report incidents of dam failures. Non-compliance with any provision of the Act results in punishable offenses, including imprisonment and fines. If such non-compliance leads to loss of lives or imminent danger, severe penalties, including imprisonment up to two years, are applicable.

Sikkim's Dam Collapse: A Tale of Regulatory Challenges

Sikkim's Tragedy:

In October 2023, a catastrophic Glacial Lake Outburst Flood (GLOF) originating from North Sikkim's South Lhonak Lake swept away India's prominent Teesta III dam at Chungthang, underscoring a profound crisis in dam safety management.

Gaps in Legislation (DSA):

The incident in Sikkim underscores critical gaps in the Dam Safety Act (DSA) of India. The legislation lacks provisions for risk-based decision-making and fails to incentivize transparency. Shockingly, essential measures such as early warning systems, risk assessments, and preventive actions, mandated by the DSA, were absent in this case. The Act's failure to make crucial information accessible to the public impedes transparent governance. Moreover, the involvement of government employees and engineers who worked on the projects in the national and state bodies compromises unbiased decision-making, perpetuating a pattern of neglect.

Complexity of Dam Safety:

Ensuring dam safety involves multifaceted tasks, from designing and constructing dams with adherence to safety margins, to real-time data recording, forecasting hazardous events, and establishing effective emergency plans. The Sikkim GLOF tragedy highlighted poor compliance at every level, from the dam's design to the inadequacy of the spillway capacity, responsible for controlling reservoir water release.

This incident serves as a stark reminder of the urgent need for comprehensive reforms in India's dam safety regulations, bridging legislative gaps, enhancing transparency, and enforcing stringent compliance measures to prevent future disasters.

Conclusion:

Researchers investigating Himalayan glacier lakes have issued warnings about potential disasters like the one in Sikkim. Regular assessments are anticipated to produce updated inundation maps and revised rule curves, crucial elements for downstream safety. It is recommended to review spillway capacity and other metrics approximately every five years to enhance dam safety measures.

Source – The Hindu