China's move to extensively dam the Yarlung-Brahmaputra as it flows through Tibet and its intention to also divert the river came into sharp focus at a conference here Monday with more than one expert saying New Delhi should immediately engage with Beijing on the issue.

"We have to be very careful how we frame our diplomacy. We have to commit them (China) to share information. We have to angle our position from the ecological standpoint," Uttam Kumar Sinha, a Fellow at the Institute of Defence Studies and Analyses (IDSA) said at the session on Water Security on the opening day of the three-day Asian Security Conference.

"The issue is understanding what China is doing. We need to get China to the table to understand what they are doing," he added.

"Clearly, it will be a long-flowing issue," said retired diplomat Leela Poonappa, who chaired the session.

Robert Wirsing, professor at the School of Foreign Service at Qatar (SFS-Q), Georgetown University, also stressed on the need for joint studies by New Delhi and Beijing on the issue of the river that is known as the Yarlung as it flows through Tibet and becomes the Brahmaputra once it enters India.

"What are China's plans? The reluctance to share information is giving it immense notoriety," he pointed out, adding: "Unless there are joint studies, the reliability of the data obtained will be in doubt."

Explaining the dimensions of the issue, Wirsing said China had already built 10 dams on the river in Tibet. Another 18 are in various stages of completion or planning.

"Then, they are eying the Great Bend (on the river just before it enters India). It's the largest and longest canyon in the world. China is planning a 38,000 MW power project that dwarfs (the) Three Gorges (project on the Yangtze river, the world's largest). China also plans to divert 20 percent of the river from Lhasa northward. The impact of this on Bangladesh would be devastating," Wirsing said.

All this would give China "immense control" of the downstream flow of the river, even assuming the Great Bend project will be a run-of-the-river dam, not to forget the hydrological impact in India and Bangladesh, he added.

Speaking about the larger issue, Wirsing said there were 263 lakes and rivers spread across 145 countries and, in the last 60 years, there had been 37 "acute" disputes relating to them while some 200 treaties and arrangements had been signed.

He noted in this context that the Indus Waters Treaty between India and Pakistan had been in existence for 60 years in spite of the two countries having fought two bitter wars.

"Even so, one can't depend on bilaterals and multilaterals. The UN Convention on the Law of the Non-Navigational Uses of International Watercourses was signed in 1997 after 30 years of intense negotiations. The sluggish ratification process has seen only 24 countries acceding to it. This is 60 percent of the 36 ratifications required before the convention comes into force.

"China voted against it. None of the 14 Himalayan states have ratified it. Clearly, we have to look someplace else," Wirsing contended.