State of Indian Dams | 10 Jan 2023

Why in News?

According to a new study by the United Nations, around 3,700 dams in India will lose 26% of their total storage by 2050 due to accumulation of sediments which can undermine water security, irrigation and power generation in future.

• The study was conducted by the United Nations University Institute on Water, Environment and Health (UNU-INWEH), also known as the UN's think tank on water.

What are the Other Highlights of the Study?

• Trapped sediment has already robbed roughly 50,000 large dams worldwide of an estimated 13 to 19% of their combined original storage capacity.
• It shows that 6,316 billion cubic metre of initial global storage in 47,403 large dams in 150 countries will decline to 4,665 billion cubic metre, causing 26% storage loss by 2050.
  • The loss of 1,650 billion cubic metre storage capacity is roughly equal to the annual water use of India, China, Indonesia, France and Canada combined.
• In 2022, the Asia-Pacific region, the world's most heavily dammed region, is estimated to have lost 13% of its initial dam storage capacity.
  • It will have lost nearly a quarter (23%) of initial storage capacity by mid-century.
  • The region is home to 60% of the world's population and water storage is crucial for sustaining water and food security.
• China, meanwhile, the world's most heavily dammed nation, has lost about 10% of its storage and will lose a further 10% by 2050.

What is the State of Indian Dams?

• About:
  • India is ranked third in the world in terms of building large dams.
  • Of the over 5,200 large dams built so far, about 1,100 large dams have already reached 50 years of age and some are older than 120 years.
    • The number of such dams will increase to 4,400 by 2050 i.e., 80% of the nation’s large dams face the prospect of becoming obsolete as they will be 50 years to over 150 years old.
    • The situation with hundreds of thousands of medium and minor dams is even more dangerous as their shelf life is even lower than that of large dams.
  • Examples: Krishna Raja Sagar dam was built in 1931 and is now 90 years old. Similarly, Mettur dam was constructed in 1934 and is now 87 years old. Both these reservoirs are located in the water scarce Cauvery river basin.
• Significance:
  • Dams provide multiple benefits including fresh water supply, water storage for irrigation, hydroelectric power generation, flood control, and improved navigation for transportation.

What are the Issues with Indian Dams?

• Built according to the Rainfall Pattern:
  • Indian dams are very old and built according to the rainfall pattern of the past decades. Erratic rainfall in recent years has left them vulnerable.
  • But the government is equipping the dams with information systems like rainfall alerts, flood alerts, and preparing emergency action plans to avoid all sorts of mishaps.
• Decreasing Storage Capacity:
  • As dams age, soil replaces the water in the reservoirs. Therefore, the storage capacity cannot be claimed to be the same as it was in the 1900s and 1950s.
  • The storage space in Indian reservoirs is receding at a rate faster than anticipated.
• Climate change:
  • Climate change has led to increased variability in the water availability and uncertainty in future water availability.

What are the Impacts of Dam Construction?

• Environmental Impacts:
  • Dams can disrupt the flow of rivers and change the downstream ecology, which can have a negative impact on plants and animals that rely on the natural flow of the river. Additionally, dams can cause soil erosion, sedimentation and flooding downstream.
• Displacement of Communities:
  • The construction of dams often leads to the displacement of local communities.
  • This can result in the loss of homes, lands, and livelihoods, which can be particularly devastating for marginalized communities such as indigenous people, farmers and fisherfolk. Example:
    • Around 1,500 people were displaced and affected by the backwaters of Sardar Sarovar Dam.
• Socio-Economic Impacts:
  • The construction of dams can also have a negative impact on the socioeconomic status of local communities. For example, it can disrupt local fishing and farming activities and lead to a loss of income for many people.
• Cost:
  • Building dams is a costly process and can put a strain on the budget of both state and central Government.
• Transparency:
  • Lack of transparency in the decision-making process can lead to a lack of public trust in dams and the organizations that operate them.

Way Forward

• The most important aspect in ensuring dam safety is the existence of accountability and transparency while taking into consideration the views of the real stakeholders--the people living downstream from the dams, who are the most at-risk group in case of a breach.
• In terms of the operational safety, the rule curve, that decides how a dam is supposed to be operated and is created when a dam is proposed, needs to be upgraded at regular intervals on the basis of environmental changes such as siltation and rainfall pattern since these would change the frequency and intensity of incoming flood into the dam as well as the spillway capacity.
  • The rule curve also needs to be in the public domain so that the people can keep a check on its correct functioning and can raise questions in its absence.

Source: ET