How was the Tungabhadra Dam Gate Swept Away?

Syllabus: GS3/Infrastructure

Context

• A flood alert has been sounded downstream of the Tungabhadra dam in Karnataka’s Koppal district after one of the 33 crest gates of the stone masonry dam across the Tungabhadra river was washed away.

Dams in India

• India has 4,407 large dams, the third highest number in the world after China (23,841) and the USA (9,263).
• Maharashtra has the maximum number of large dams followed by Madhya Pradesh and Gujarat.

Dam Failures in India

• The first failure was recorded in Madhya Pradesh during 1917 when the Tigra Dam failed due to overtopping. 
• The worst dam disaster was the failure of Machu dam (Gujarat) in 1979 in which about 2000 people died.  
• There are 40 reported failure cases so far.

Major threats to dams in India

• Aging: With over 6,000 dams in India, ranked third globally in terms of large dams and approximately 80% of these dams exceeding 25 years of age while 234 surpassing the century mark, ensuring their safety is of paramount importance.
  • For India, 2025 is set to be a big year as more than 1,000 dams would turn roughly 50 years or older.
• Sediments & siltation: Accumulation of sediments and siltation decreases a reservoir’s capacity over the years.
• Flooding: The country gets concentrated rainfall every year for a designated time period as opposed to distributed rainfall, which contributes to the dams’ vulnerability.
  • In India, the downstream areas are often exposed to flood disasters & flooding has caused 44% of dam failures in India.
• Seismic threat: Some of the Himalayan dam systems, including the Tehri Dam, are in an active seismic area given that the Himalayan mountain system is constantly changing and growing giving rise to several tectonic movements.

Dam Safety Act, 2021

• About: It is an Act to provide for the surveillance, inspection, operation, and maintenance of the specified dam for prevention of dam failure related disasters.
  • It also provides for an institutional mechanism to ensure their safe functioning and for matters connected therewith or incidental thereto.
  • These are dams with height of more than 15 meters, or height between 10 meters to 15 meters with certain design and structural conditions.
• Provision of National Bodies:
  • The National Committee on Dam Safety (NCDS): Its functions include evolving policies and recommending regulations regarding dam safety standards. It will be chaired by the National Water Commissioner.
  • The National Dam Safety Authority: Its functions include implementing policies of the National Committee, providing technical assistance to State Dam Safety Organisations (SDSOs), and resolving matters between SDSOs of states or between a SDSO and any dam owner in that state.
• Dam Safety Unit: Dam owners are now required to have a dedicated Dam Safety Unit, prepare Emergency Action Plans, and conduct Comprehensive Safety Evaluations at regular intervals.
  • Head of dam safety: Chairman of the Central Water Commission (CWC) would head dam safety protocols at the national level.
• Constitution of state bodies: State will constitute two bodies i.e. State Committee on Dam Safety and State Dam Safety Organisation.  
  • These bodies will be responsible for the surveillance, inspection, and monitoring the operation and maintenance of dams within their jurisdiction.
• Classification of dams: Provisions require States to classify dams based on hazard risk, Conduct regular inspections, Create emergency action plans, Institute emergency flood warning systems, Undertake safety reviews and period risk assessment studies,Report and record incidents of dam failures. 
• Non-compliance:
  • Failure to comply with any provision of the Act is punishable with imprisonment and/or fines.
  • If such obstruction or refusal to comply with directions results in loss of lives or imminent danger thereof, [entity] shall be punishable with imprisonment for a term which may extend to two years.

Other initiatives taken by the government

• Dam Rehabilitation and Improvement Project (DRIP) Scheme: Under the World Bank funded DRIP Phase-I scheme, which was implemented between 2012 to 2021, 223 existing dams located in 7 States were comprehensively audited and rehabilitated.
  • Now the government has taken up DRIP Phase-II & III scheme envisaging rehabilitation and safety improvement of 736 dams located in 19 States. 
• Dam Health and Rehabilitation Monitoring Application (DHARMA), has been developed to capture authentic data pertaining to all large dams to act as information repository.
  • This tool has the appropriate access to policy makers, project managers, and dam managers to review the information and take appropriate action.

Way Ahead

• Automated Monitoring Systems: Implement real-time monitoring systems that use sensors to detect structural weaknesses, seepage, and other signs of dam distress.
• Comprehensive Safety Audits should be conducted at regular intervals to assess the overall integrity of the dam.
• Hazard Potential Classification: Classify dams based on the potential consequences of their failure.