Whether Mekong delta together with its ecosystem is sustainable developing or not?

Mekong River in Vietnam is about 4.300 km away from Tibet. Half the length flowing through Yunnan - China, then down to Thai, Laos and pour into Cambodia. Hitting Phnom Penh, the capital of Cambodia, it creates a confluence of 4 branches together with its delta before draining into the South China Sea south of Ho Chi Minh City (formerly Saigon).

The lower Mekong region (covering Vietnam and Cambodia) has three major reservoirs to store water:

  1. The Tonle Sap in Cambodia has a capacity of 80 billion m3.
  2. Dong Thap Muoi has capacity 10 billion m3.
  3. The Long Xuyen Quadrilateral Zone (Long Xuyen - Chau Doc - Ha Tien - Rach Gia) capacity of 9 billion m3.

During rainy season, when Mekong River rises, the Tonle Sap expands 5 times bigger over the dry season. At that point, the water steadily come down to Vietnam, the two big branches of the Rivers spill into the 2 giant natural sunken areas.

Thanks to the three major reservoirs (one in Cambodia, two in Vietnam), despite strong current with enormous water (~ 36.000 m3/sec), the two branches’ still rising slowly, not suddenly flooding , as terrible devastation encountered in Central & North Vietnam. The local people call it “the floating season” and they have a harmonious living experience – considering flood is a reward from Mother Nature.

In dry season, Tonle Sap reverse the flow (Tonle Sap is the only river in the world, as far as I know, with a seasonal two-way flow). The water from Tonle Sap brings several tons of fish down to Vietnam. At the same time, water from other two reservoirs – Dong Thap Muoi & Long Xuyen Quadrilateral Zone also begins to gently leak to the rivers, lasting between 2 and 4 months, helping to push away salty water from the Sea.

It is not simply about the tide. Base on the lunar calendar or the moon, locals know exactly whenever water ups & downs. Some months it is “big water”, “poor water”, and they have season called “floating water”

Last year, I unintentionally escorted a tour with 2 scientists from Holland. They are climate - change experts looking forward to a conference in Can Tho - Vietnam with Prime Minister Nguyen Xuan Phuc about “Impacts of global warming to Mekong Delta”. He said the following that still inspire me up to now:

From hundreds years ago, over generations, local people were accustomed to living with the natural rhythms of the rivers: during the day, during the month, and formed a “civilization of water”. But the rhythm of Mother Nature here has suffered many “human disasters”, being destroyed by many giant hydroelectric dams blocking the water itself upstream. Mekong River will be covered by approximately 468 hydro-power dams by 2030. These dams not only keep water but also prevent the silt. Tonle Sap has being narrowed and depleted. Two gigantic reservoirs in Vietnam with a total capacity of nearly 20 billion m3 of water are also being curtailed due to the dams people have made to make electricity, expand residential, and do 3 crops of rice per year. They have to drill more and more wells, penetrating deep into the ground, making exhausted fields. Thereafter, they used more chemicals and fertilizer as well. Consequently, the land depression is 10 times the sea level rises! Salty water has being come deeper in mainland for the last few years in dry season causing ecosystem disorders.

All in all, the benefits of the scheme outweigh the disadvantages.

References:

  1. https://asia.nikkei.com/Politics/International-relations/Mekong-River-leaders-grow-hushed-on-hydropower-fears-at-summit?fbclid=IwAR3aiht4CP_fWXaZpfvqymaRDGCLIsL5kc-Zk7Sq33lyFVDuwUF9r5ZHTdw
  2. https://www.britannica.com/place/Mekong-River
  3. https://www.voatiengviet.com/a/song-me-kong-uy-hoi-ngo-the-vinh-dong-bang-song-cuu-long/4249106.html?fbclid=IwAR1TnK09oCcYO0zSt7d43N33uUW4GAUBZyl0cD6Sk5uxVf-M4_PilANpQ9w
  4. https://asiancorrespondent.com/2018/01/laos-pushes-ahead-mekong-dams-despite-environmental-risks
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