China dam on Brahmaputra won’t be harmful if water not diverted

If water is not diverted through China's proposed super dam to be built on the Brahmaputra River in Tibet, there will be no harm to the water flow downstream, Bangladesh, say experts.

China will build a super hydropower plant in the lower reaches of Yarlung Zangbo – the Tibetan name for the Brahmaputra.

A proposal has been put forward in China's 14th Five-Year Plan to be implemented from next year, Global Times reported on Sunday, quoting Yan Zhiyong, chairman of the Power Construction Corporation of China.

Water experts and activists in Bangladesh say the proposed dam will not have any adverse impact on the Brahmaputra's water flow downstream to Bangladesh.

Ainun Nishat, a renowned water resources expert, told The Business Standard that if the proposed dam operates on the run-of-river basis, it will not reduce water flows to Bangladesh. Instead, its controlled water discharge will increase water flow downstream during the dry season.

"In case of a water diversion, negative impacts need to be measured based on the volume of diverted water," Nishat said, adding that the only potential direction for water diversion from Medog is inner-Mongolia.

"Such a diversion will be very expensive," he said.

In 2015, China commissioned the $1.5 billion Zangmu Hydropower Station, while the development of three other dams are now underway at Dagu, Jiexu and Jiacha – the Three Gorges.

Although the dams are either built in the upper and middle reaches of the river, the proposed super dam will be in the lower reaches for the first time, to tap huge potentials of power generation.

Medog is the last county in Tibet that borders India's Arunachal province. If the dam is constructed here, the Grand Canyon of Yarlung Zangbo, located in Medog, will work as a natural reservoir for hydropower.

Global Times reported that the mainstream of the Yarlung Zangbo River has the richest water resources in the Tibet Autonomous Region, about 80 million kilowatt-hours, while the 50-kilometre section of the Yarlung Zangbo Grand Canyon has 70 million kWh that could be developed with a 2,000-metre drop, which is equivalent to more than 3 Three Gorges power stations in Hubei province.

The proposed 60 million kWh hydropower project could provide 300 billion kWh of clean, renewable and zero-carbon electricity annually. "The project will play a significant role in realising China's goal of reaching a carbon emissions peak before 2030 and carbon neutrality in 2060," Global Times quoted Yan.

As a lower riparian country, what will be the potential harm to Bangladesh with such an establishment?

Generally, any intervention in natural river water flow has negative impacts. Initially, after commencing the dam's construction, it will push the relocation of more than 1,400 inhabitants in Medog. The river-based ecology will be affected, and water quality will deteriorate after passing through the hydropower plant.

However, after the water travels through a long route of more than 1,000 kilometres from Arunachal, water quality will be restored for Bangladesh.

"As the proposed site is a distance from Bangladesh, negative impacts will be negligible," Nishat said.

Most importantly, the lion's share of the Brahmaputra run-off comes from hilly rainfall, and the catchment area is located just downstream of the proposed dam.

Sheikh Rokon, secretary general of Riverine People – a Bangladesh-based voluntary organisation, however, is sceptical about the consequences.

He said intervention to natural river water flow might slow down or speed up the siltation process in Bangladesh through the Brahmaputra.

"Hence, construction of the proposed dam needs to be discussed at the state-level before it starts," he added.

Rokon said that rather than the China-India or China-Bangladesh set-up, environmental activists have long been demanding a discussion of the transboundary river water issues, and resolution through multi-lateral arrangements.

State Minister for the Water Resources Ministry, Jahid Faruk and Deputy Minister AKM Enamul Hoque Shameem could not be reached for comments.