Chinese researchers have warned that the Brahmaputra River in Tibet, where China is building the world's largest dam at an estimated cost of US$168 billion, could experience increased runoff and heightened flood risks over the course of this century, PTI reported on Monday. Yaani, US$168 billion means about 16,800 crore dollars spent on one river project upstream of India.

Source: PTI via Daily Jagran

Researchers from the Chinese Academy of Sciences and Yunnan University used tree-ring width chronologies from the southeastern Tibetan Plateau to reconstruct the river's runoff history from 1325 to 2020. They combined the reconstruction with climate data to create a model that projected that river runoff would increase under future climate scenarios, along with a possible rise in high-runoff events such as floods.

"These results provide a long-term perspective on hydroclimatic variability in the Yarlung Tsangpo River and a scientific basis for assessing future water-resource risks," the team said in a paper published in the journal China Science Bulletin on October 8, the Hong Kong-based South China Morning Post reported on Monday. Yarlung Tsangpo is the name used in Tibet for the river that flows into India as the Brahmaputra.

Source: PTI via Kalimpong News (SCMP reporting)

Why it matters downstream

The researchers said future runoff should be considered in planning "water resource development and storage infrastructure" and in assessing transboundary water risks in the region. The Tibetan Plateau has been warming at about twice the rate of the global average, affecting its ice cover and hydrological cycle, according to the researchers.

They emphasised that changes in the river not only reflect the hydrological system within the plateau but also affect drought and flood patterns in South Asia. "In recent years, with the ongoing warming of the climate, the hydrological regime of the Yarlung Tsangpo River basin has been undergoing significant changes," they said. For India and Bangladesh, which sit downstream on the Brahmaputra, a Chinese research team's own warning about more runoff and floods adds scientific weight to a long-running concern about the mega dam.