VietNamNet Bridge – Experts have warned the construction of a dozen dams on the Mekong River’s mainstream is threatening the river’s ecology and the wellbeing of a lot of residents in the river basin.

Illustrative image -- File photo

The plans to build 11 hydropower dams on the Mekong River’s mainstream in Thailand, Laos and Cambodia would leave negative impact on the environment and the livelihoods of millions of people.

Experts, speaking a seminar in HCMC last week, underscored the need to fully assess possible changes of river flows, flooding, alluvium and saltwater intrusion which would affect the river’s ecology and the wellbeing of people.

According to Deputy Minister of Natural Resources of Environment Nguyen Thai Lai, the Mekong River basin is home to around 60 million people. In 1970, countries in the basin proposed seven large hydropower dams on the river’s mainstream but those plans were shelved over fear of substantial negative impact.

Regional countries in 1994 proposed 11 dams but scientists warned they would cause severe environmental impact.

A research team was set up to assess the impact of those planned dams on the mainstream of the Mekong River on 10.5 million hectares in Vietnam and Cambodia, including nearly four million hectares in Vietnam’s Mekong Delta region.

These plans were projected to affect river flows and cause water flows to decline 60% in Cambodia’s Kratie Province and 40% in Tan Chau and Chau Doc of Vietnam, heard the seminar held by the Ministry of Natural Resources and Environment.

Similarly, alluvium and nutrients in the river within the surveyed area would fall 65%. There would be barrier effects on major fish migrations.

The damming plans would also lead to a 50% reduction in fish catches in both Vietnam and Cambodia. The total value of fish catches on the Mekong River’s downstream is estimated at US$7 billion a year, with migratory fish accounting for half.

A plunge in fish catches would put at risk food security and the livelihoods of residents in flooded areas in Cambodia and Vietnam’s Mekong Delta.

The research also found transportation in the lower reaches of the river would become insecure as dams might discharge huge volumes of water unexpectedly.

The 11 dams planned on the Mekong River’s mainstream are Pak Beng, Luang Prabang, Xayabury, Pak Lay, Sanakham, Pak Chom, Ban Koum, Lat Sua, Don Sahong, Stung Treng and Sambor.

Xayabury dam began construction in 2012. Lao experts attending the seminar in HCMC last week said the project is 55% complete and could be ready by 2018.    

SGT