A recent study by the United Nations reveals the worrying fact that roughly 3,700 dams in India will lose about 26% of their total storage by 2050. The loss is predominantly due to sediment accumulation, posing a potential threat to future water security, irrigation and power generation.
This research was conducted by the United Nations University Institute on Water, Environment and Health (UNU-INWEH), the UN’s think tank on water.
The conclusions of the study are not only alarming for India. It has been estimated that trapped sediment has robbed approximately 50,000 large dams across the globe of 13-19% of their original storage capacities.
Moreover, initial global storage in 47,403 large dams spread over 150 countries is predicted to decline from 6,316 billion cubic metres to 4,665 billion cubic metres. This implies a reduction of 26% in storage by 2050.
Asia-Pacific, the world’s most dammed region, is estimated to have lost 13% of its initial dam storage capacity in 2022 itself. By mid-century, it is expected to lose nearly a quarter of this capacity.
China, the world’s most dammed nation, has already lost about 10% of its storage and is projected to lose another 10% by 2050.
The Status of Indian Dams
India ranks third globally in building large dams, with about 1,100 out of 5,200 large dams already over 50 years old. Some are even older than 120 years. By 2050, this number may rise to 4,400, meaning 80% of the nation’s large dams may become obsolete.
This predicament is particularly worrisome for hundreds of thousands of medium and minor dams whose shelf life is even lower.
Despite their age, dams continue to serve multiple purposes, including supplying fresh water, storing water for irrigation, generating hydroelectric power, controlling floods, and facilitating improved navigation for transportation.
Problems with Indian Dams
Several issues plague India’s dams. They are old and were constructed according to the rainfall patterns of past decades, leaving them vulnerable to the erratic rainfall patterns of recent years.
As these dams age, reservoirs fill up with soil, leading to a decline in storage capacity. This drop has been faster than anticipated.
Climate change has introduced further variability in water availability, causing uncertainty about future supply.
The Ripple Effects of Dam Construction
Dam construction carries impacts beyond just the immediate infrastructure. Environmentally, they can disrupt river flows and alter downstream ecologies adversely affecting the plant and animal species that depend on them.
Dams often displace local communities leading to loss of homes, lands, and livelihoods. This displacement is particularly devastating for marginalized groups such as indigenous peoples, farmers and fisherfolk.
They can also negatively affect the socioeconomic status of local regions by disrupting fishing and farming activities and causing income loss.
Financially, building dams is a significant expense adding stress to state and central budgets.
The Steps Taken So Far
Water and water storage being state subjects under the 7th Schedule of the Constitution of India, legislating dam safety falls under the jurisdiction of state governments.
However, the Central Government can enact legislation overseeing dam matters in certain situations.
The Central Water Commission (CWC) offers technical expertise and guidance on dam-related affairs at the national level. It is tasked with researching dam safety and creating standards for dam design and operations.
Under the Dam Safety Act of 2021, all specified dams across India now fall under surveillance, inspection, operation and maintenance.
The Way Forward
To ensure dam safety, it is critical that there are accountability and transparency taking into account the views of those most at risk — the people living downstream from the dams.
It is also essential that the rule curve, which determines how a dam is to be operated and is developed during the dam proposal stage, be regularly updated based on changing environmental factors like siltation and rainfall patterns.
This rule curve should also be publicly accessible so that people can monitor its correct functioning and raise concerns if necessary.
