The biggest threat the Mekong River's ecological system faces is not the controversial dam- building projects, as some NGOs claim, but the long-time deforestation on the river basin, a Thai expert contended.

The Mekong River [File photo]?

Speaking with Xinhua before the 4th Summit of the six-country Greater Mekong Subregion-Economic Cooperation (GMS), Surachai Sirikrai, professor with the Faculty of Political Science of Thammasat University in Bangkok, looked back on the history of how the riparian countries have explored and utilized the rich resources provided by the Mekong River.

"For decades, the six countries have worked with each other in utilizing the river properly and also in protecting it. During this process, problems emerge. There are numerous debates and even quarrels concentrating on one single topic: whether or not we should build dams on the river," said the professor, who have studied and given lectures on the GMS scheme for many years.

Many opponents of dam projects insist that building dams on Mekong River would lead to the reduction of its water quantity, thus adversely affecting the balance of its ecological system and posing threat to the downstream fertile farmlands, which are the main rice production bases in Cambodia and Vietnam.

The most intense opposition comes from NGOs.

"During the 1990s, a great concern for climate change and global warming came out. The NGOs, especially those from the western world, began their campaign against dam-building," said Surachai. "However, a lot of people seem not to have a correct understanding about this issue. They believe that the water of Mekong River reduces because of the dams, but that's only part of the truth."

"To know this, you must know how a river is formed and where the water comes from. It is wrong to think that China's Tsinghai- Tibetan is the only source of the Mekong River. It also absorbs water from all its neighboring areas," he explained, estimating that China's higher grounds only contribute around 11 percent to 13 percent of the water amount of the Mekong River.

Consequently, in the early period of dam-building, he said, as the dam tries to gather water in the upstream, the immediate downstream area might face a slight reduction of water, but after the dam starts to release water, the situation will resume normal.

What has been ignored by many people but actually affects the ecological system of Mekong River is deforestation, said Surachai, calling it a "business" which local governments cannot control.

"The fact that a great number of forests near the river are being cut down is a much bigger threat than building dams," he said. "The timbers are exported and sold to other countries. There are not enough trees in the catchment area to absorb water. As a result, the river will dry up every year." With its headwaters thousands of meters high on the Tsinghai-Tibetan Plateau, the 4, 800-kilometer-long Mekong River flows through six countries -- China, Myanmar, Thailand, Lao, Cambodian and Vietnam.

The six countries started the GMS in 1992 to promote economic and social development, irrigation and cooperation.