The Chinese government on Thursday mounted a defence of its dams on the Brahmaputra and Mekong rivers, assuring its seven neighbours, including India, who have voiced concerns about the projects that downstream flows will remain unaffected.

Besides India, which raised the construction of a 510 MW dam on the Brahmaputra in talks with the Chinese leadership this week, Thailand, Laos, Vietnam and Cambodia had expressed similar concerns over eight dams being built on the Mekong River.

Referring to the Mekong dams, Chinese Foreign Ministry spokesperson Hong Lei said on Thursday that China took into account the considerations of its lower riparian, or downstream-lying, neighbours in planning the projects.

“China has always fully considered the concerns of the countries in the lower reaches of the Mekong River in its water resources exploitation,” he said at a briefing.

Amid concerns that the dams had worsened drought situations in the Mekong region, Cambodia's Prime Minister said on Wednesday that the drought was caused by natural weather conditions, and not by China's dams.

“That the Mekong River, or other rivers, have lower or higher levels of water depends on the rain,” he was quoted as saying by AFP, following a meeting with leaders from Thailand, Laos, Vietnam and Myanmar. “So please don't be too extreme about the environment and don't say hydropower dams cause water levels to drop in the lower Mekong. If you think that, it is a mistake.”

While China has stressed that its eight dams would help, and not hinder, flood management, the Mekong River Commission (MRC) — represented by Thailand, Laos, Vietnam and Cambodia — has called on China to share more data and be more transparent about its plans. China has been reluctant to join the MRC.

In talks in Beijing this week, India voiced similar concerns, calling on China to continue sharing data regarding its plans for the Brahmaputra, or the Yarlung Tsangpo as it is known in Tibet. While India and China have set up a joint expert-level group to exchange hydrological data, the absence of a water-sharing treaty means the exchange of information is limited.

China has said that the dam on the Brahmaputra will not affect downstream flows, and it will not build a storage reservoir. “The river flow will not be stopped during construction,” Li Chaoyi, chief engineer of China Huaneng Group, which is the contractor for the project, told the official Xinhua news agency. “After it becomes operational, the water will flow downstream through water turbines and sluices, thereby not affecting the downstream water levels.”

The official Global Times newspaper reported that in China too, some environmental groups and some engineers had voiced concerns over the Brahmaputra dam. “The diversified fauna and flora there have evolved over tens of millions of years and will be damaged. Blocking the river may also overturn the balance of the region's ecosystem,” said Wang Yongchen of the Beijing-based Green Earth Volunteers.

The newspaper also quoted an engineer with the Sichuan bureau of Geological Exploration and Exploration of Mineral Resources warning that the dam “may not function well at a high altitude, where rivers are likely to be frozen for most of the year” and that the area was “subject to natural disasters such as earthquakes.”

Regardless of these concerns, construction of the dam started on November 12, following the damming of the river on November 8.