National Dam Safety Authority (NDSA)has constituted an expert committee to examine the dam safety of the Kaleshwaram Lift Irrigation Project (KLIP).
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The KLIP is the world’s largest multi-stage lift irrigation project.
It is constructed on Godavari River in Telangana.
The NDSA, a part of 4 tiered institutional structure under the Dam Safety Act, 2021 (refer to the box), established a six-member committee to probe the sinking of piers at the 'Medigadda (Laxmi) barrage' of the KLIP.
Led by J. Chandrasekhar Iyer, former chairman ofthe Central Water Commission (CWC), the committee will assess the hydraulic, structural, and geotechnical aspects of the dam.
CWC is a premier Technical Organisation in the country in the field of water resources.
It is as an attached office of the Ministry of Jal Shakti.
About Dam Safety Act, 2021
Purpose: Provides for proper surveillance, operation and maintenance of the specified dams to prevent dam failure.
Outlines responsibility of stakeholders: Dams are owned, operated and maintained by State Governments or Departments/Boards/ CPSUs/Private Agencies, etc.
About Dams
Dam means any artificial barrier and its appurtenant structure (barrage, weir) constructed across rivers or their tributaries to impound or divert water.
A large dam refers to a dam with:
a maximum height of more than 15 metres from its deepest foundation to the crest or
a dam between 10 and 15 metres in height from its deepest foundation that fulfils some specified conditions.
Key utility of dams: Water for drinking, irrigation, and industrial use; flood control; hydropower generation; inland navigation; recreation, etc.
Dam constructions relates in displacement and cultural loss, loss wildlife and their habitats, interstate conflict (over water safety, water sharing, etc.).
Major Dam Failures across the globe include
1975: Banqiao dam failure in China resulted in collapse of 60 other downstream dams and killed more than 80,000 people.
1979: Machchhu Dam failure in Morbi, Gujarat claimed over 2,000 lives.
2023:Derna dam collapse in Libya claimed over 3,800 lives.
Concerns associated with the safety of dams
Ageing dams: Dams usually have a defined lifespan beyond which they may become unsafe or uneconomic.
Seismic vulnerability: Large dams in India are often built in seismically active areas, making them vulnerable to earthquakes.
For example, the earthquake in Bhuj (Gujarat) in 2001, led to liquefaction in the foundation of Chang Dam.
Flood: For example, in October 2023,Chungthang Dam Sikkim’s highest dam was washed away during flash floods caused by a glacial lake outburst of South Lhonak Lake.
Overtopping: Overtopping (gully erosion) failures result from the erosive action of water on the embankment.
Sedimentation: Abrasive sediments can damage hydroelectric turbines and other dam components. It also reduces the storage capacity of dams.
Around 3700 dams in India will lose 26% of the total storage by 2050 due to the accumulation of sediments (United Nations).
Financial: Poor financial situation typically translates into irregular maintenance and upkeep of other parts of the power plant.
Non-compliance with legislative mandates: For example, the CAG audit report of Gandhi Sagar in Madhya Pradesh highlighted that the SDSO did not comply with recommendationsby the CWC on remedial measures.
Initiatives for dam safety
National Register of Large Dams (NRLD): It is the nationwide register of Large Dams complied and maintained by CWC.
Dam Rehabilitation and Improvement Project(DRIP): The 2nd and 3rd Phase of DRIP envisages comprehensive rehabilitation of 736 dams across 19 States.
The Project will receive loans, both from the World Bank and the Asian Infrastructure Investment Bank (AIIB), for disbursal among States and three central agencies (CWC, Damodar Valley Corporation & Bhakra Beas Management Board).
National Centre for Earthquake Safety ofDams: Locatedat MNIT Jaipur (Rajasthan), the centre will enhance the Structural and Earthquake Safety of Dams in India.
India Water Resource Information System (WRIS): It provides a single window solution for all water resources (including dams) data and information on the GIS framework.
Dam Health and Rehabilitation Monitoring Application (DHARMA): Developed to capture important data for all dams. This is a step to move towards the application of Artificial Intelligence (AI) in dam safety.
Seismic hazard analysis information system (SHAISYS) tool: Aims to ascertain the extent of seismic forces and their implication on the safety of the dam structures.
Dam Safety Review Panel: Some states have created these panels for comprehensive audit of their dams.
Global
World Commission on Dams: Established by the World Bank and IUCN in 1998 to review the development effectiveness of large dams and develop guidelines for the planning, monitoring and decommissioning of dams.
International Commission on Large Dams (ICOLD): It is a non-governmental International organisation founded in 1928. It provides a forum for the exchange of knowledge in dam engineering.
Indian National Committee on Large Dams (INCOLD) is the Indian Committee interacting with ICOLD.
Way ahead to ensure dam safety
Decommissioning of ageing dams: Generally, decommissioning refers to the complete removal of the dam and its associated structures or partial reduction or lowering of the dam’s height.
Dam decommissioning is highly site-specificand demand careful planning to minimizes public health and safety risks to downstream communities.
Planning, design and construction: Design methods and criteria should conform with the current state-of-the-art technology related to dam safety.
Specific problems expected as a result of severe weather conditions, such as very low winter temperatures, should be defined in formulating design criteria and safety standards for dams.
Subsurface dams: Countries like Japan have created multiple sub-surface dams as an alternative to surface dams. This could be replicated in India as well.
Sub-surface dams capture ground waters flowing fairly near the surface of the ground. This water can be accessed via wells upstream from the dam. Since the water is stored within the aquifer,
submergence of land can be avoided,
there will not be any evaporation loss from the reservoir,
no siltation takes place in the reservoir,
the potential disaster like collapse of dams can be avoided.
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