Flooding Mekong In Dry Season: Should Laos Also Be Responsible?

1 April 2016 | By TERRA

Translated from Thai น้ำโขงท่วมหน้าแล้ง  ลาวต้องร่วมรับผิดชอบด้วยหรือไม่

Recently, water level of Mekong River has been exceptionally high due to upstream Chinese dam discharge. From March 15 to April 10, 2,000 cubic meters of water will be released every second from its dam for almost a month. China claimed that the water was sent downstream to alleviate drought condition.

On March 25, 2016 Lao government announced it too would support this relief to alleviate drying downstream countries (Land Link). It stated that, since March 23, Laos has been contributing 1,136 cubic meters of water every second from dams on Mekong tributaries—Nam Ou, Nam Khan, Nam Ngum, and Nam Thuen. As a result, the higher water level submerges riparian beaches and affects riverbank gardens along Mekong River, starting from Chiang Khan, Loei to Khong Chiam, Ubonratchatani.

Laos’ dam discharge urges us to question its largesse, especially on its 2 most recent completed dams on Nam Ou. The question is similar to the one asked earlier for China and its control over the Mekong water level since the construction of Manwan Dam in 1993; as the main purposes for its dam discharge were not to relieve drought in dry season but to support its large cargo ships navigation, electricity generations and preparation for upcoming rainy season.

At the location where Nam Ou and Mekong meet is Luang Prabang’s important tourist destination, Tham Ding (Ding Cave). There is also a Mekong hydrological station named “Luang Prabang Hydrological Station” which Mekong River Commission (MRC) has been recording water level and flow rate.

Between Chiang Saen Hydrological Station, where Mekong first greets Thailand, and Luang Prabang Hydrological Station, Nam Ou is the largest tributary of Mekong. (See Figure 1 for map of hydrological stations in Thailand and Laos)

To seek whether the Mekong flow rate is natural, it is important to look at the following findings from the flow rate records at Luang Prabang Station:

1.     In 1993, Mekong flow rate at Chiang Saen station changed due to Manwan Dam. However, the flow rate at Luang Prabang, where Nam Ou meets, continued to drop normally. Thus, the construction of Manwan Dam influences Mekong flow at Luang Prabang to fluctuate (Figure 2).

2.     In 2003, the flow rate at Luang Prabang was still highly influenced by upstream Chinese dams. Nonetheless, the flow rate continued to drop normally after the confluence of Nam Ou and Mekong. (Figure 3)

3.     In 2010, 2012, 2013 and 2014, the flow rate at Luang Prabang was still highly influenced by upstream Chinese dams. However, the flow rate of Nam Ou dropped significantly between January and April. Notice how the flow rates at Chiang Saen Station and Luang Prabang Station become very similar. (Figure 4, 5, 6, 7)

4.     In 2015 and 2016, upstream Chinese dams continue to fluctuate the water flow at Luang Prabang Station. Nonetheless, it should be noted that Nam Ou volume, starting in January, increased to more than 800 cubic meters per second or higher than the normal rate in 1993, which was before the completion of Nam Ou dams. (Figure 8 and 9)

At Luang Prabang, thirty to fifty percent of Mekong discharge from Chiang Saen Station (or upstream Chinese dams) is from Nam Ou. This means that any change of Nam Ou, whether fluctuating water flow or higher discharge, would affect downstream Mekong riparian communities that settle along the 800-km Thai-Lao border starting from Chiang Khan, Loei to Khong Chiam, Ubonratchatani.

Overall, these numbers simply point out that Laos has been discharging water from dams on Nam Ou since 2015. Even this year, Laos continues to discharge great volume between January and March 2016. In conclusion:

  1. As well as China, Laos must also take responsibility on damages, posed by its Nam Ou dams, on downstream Mekong riparian communities.
  2. Laos has not disclosed information or inform other Mekong countries about the discharge from Nam Ou dams. On the other hand, Laos only notified other Mekong countries that the discharge, at the rate of 1,136 cubic meters per second, was joint effort with China to alleviate drought. When in fact, Laos has been discharging water since 2015.
  3. Impacts, created by tributary dams discharge, will completely change Mekong downstream flow. It will affect all aspects of Mekong River and communities that depend on Mekong, including the riparian ecosystems and Mekong hydrology especially in dry season.
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