Context: Recently, a US-funded study has highlighted the possible impact of China’s dams on the Mekong river (known as Lancang river in China) and countries downstream.
Key Points of the study

• The study said six dams built since the commissioning of the Nuozhadu dam in 2012 had altered natural flow of the Mekong river.
• It has raised fresh questions on whether dams being built on other rivers that originate in China, such as the Brahmaputra, may similarly impact countries downstream.
• Based on a satellite data from 1992 to 2019, the study found that there was severe lack of water in the lower Mekong.
• This is despite China’s southwestern Yunnan province having above-average rainfall from May to October 2019.
• The Mekong flows from China to Myanmar, Laos, Thailand, Cambodia and Vietnam.
• The Mekong River Commission, which comprises Cambodia, Laos, Thailand, and Vietnam, has said more scientific evidence was needed to establish whether dams caused a 2019 drought.

China’s Stand

• It has called the study groundless and highlighted the drought faced by Yunnan because Lancang only accounts for 13.5% of Mekong’s flows.
• China has maintained that the dams, it is building, are run of the river dams which store water for power generation.

India’s Stand

• According to Indian experts, the study is not conclusive because it only considers the water flowing into the lower basin at one station in Thailand.
• It did not consider other dams and water-use along the course of the river.
• The lower basin is not entirely dependent on flows from China, but also receives water from tributaries in all other countries it flows in, which the study did not account for.

India’s concerns:

• India has long expressed concerns over dam-building on the Brahmaputra.
• In 2015, China operationalised its first hydropower project at Zangmu, while three other dams at Dagu, Jiexu and Jiacha are being developed.
• India, for the most part, doesn’t have a water quantity problem but a management one.
• Indian officials have said the dams are not likely to impact the quantity of the Brahmaputra’s flows because they are only storing water for power generation.
• Moreover, the Brahmaputra is not entirely dependent on upstream flows and an estimated 35% of its basin is in India.
• India does not have a water-sharing agreement with China, but both sides share hydrological data.
• India worries more about activity in China affecting quality, ecological balance, and flood management.
• China cooperates with India for warnings on how floods are moving down the Yarlung Tsangpo and into the Brahmaputra, so that India can warn its population living in low-lying areas and move them safely to higher ground.

About Brahmaputra river

• The Brahmaputra is a trans-boundary river which flows through China, India and Bangladesh.
• It is called Yarlung Tsangpo in Tibet, Siang/Dihang River in Arunachal Pradesh and Luit or Dilao in Assam.
• It has its origin in the Chemayungdung Glacier, Manasarovar Lake region, near the Mount Kailash, located on the northern side of the Himalayas in Tibet.
• It enters into India through Arunachal Pradesh and flows southwest through the Assam Valley as Brahmaputra and south through Bangladesh as the Jamuna.
• In the vast Ganges Delta, it merges with the Padma (popular name of the river Ganges in Bangladesh) and becomes the Meghna and empties into the Bay of Bengal.