Montree Chantawong, Mekong Butterfly,
March 6, 2024
Clear Water from Mekong Dams, Dirty Energy, Gone Sediment[1]
Electricity from hydropower dams has been advertised as clean energy for the main reason that there is no fuel cost. No fossil fuels are used in the production, only “water”, claimed as renewable and clean energy, is used with no pollution making. This is such a rough and selfish explanation avoiding to comprehensively explain about “Supply Chain” which is “a process that creates a particular product or service showing how more or less clean it is in every single manufacturing process”.
Clean energy as claimed does not come from normal “water”, but by raising the water level up to 50-60 or even 100 meters creating a large reservoir area. Whether it is called a reservoir in the river or not, it left behind the ruined homes and communities of those who had to be evacuated; the ruins of river ecosystems as well as all aquatic lives both upstream and downstream of dam. The abundance of the river ecosystem has been destroyed both by changes in flow and decrease in sediment load throughout the river below the dam. Electricity from dam is therefore not clean energy, the tradeoffs in ecosystem; environment; biodiversity as well as community’s livelihood have not been mentioned and will be a hidden cost that the ecosystems and communities have to bear forever.
The disappearance of the Mekong sediment caused by dams already built in China and Lao PDR, such phenomenon has been happening more obviously in the dry season during the past 5 years. It was overlooked by responsible agencies both at the national and regional levels even though the problems have become evident since the end of 2019, for example, the blooms of the Mekong algae as well as small mussels (or Hoi Rog Kuai); communities are unable to fish and more severe erosion of the river bed, etc.
Agency directly in charge of the Mekong River is the Office of the National Water Resources (ONWR) as a secretariate of the Thai National Mekong Committee has had a meeting on March 23, 2020 to analyze the Mekong-color-changing phenomenon from brown color of the flowing sediment to clear indigo color of the very low sediment condition. The analysis of the Mekong River quality in the area of Muang Nakhon Phanom and Lao PDR’s Thakhek found that “General study results are in normal range and not harmful to aquatic animals as well as the ecosystem. The water quality of the Mekong River is normal, except for the suspended sediment which decreases tremendously. It was predicted that the water quality in terms of sediment condition will increase back to normal when entering the flood season this year”.[2] It did not specify what consequences of the great decrease of the Mekong sediment will cause problems since there is no standard score for the amount of sediment (suspension) for surface water, it is therefore impossible to compare.
Even the regional organization like the Mekong River Commission Secretariat (MRCS) has issued a press release on December 9, 2019[3] pointing out that the main reason of why the Mekong has no sediment is its low flow rate, leading to the algae bloom in the Mekong River. In addition, the MRCS’ news on December 8, 2020[4] again mentioned that less water than usual of the Mekong was the cause of the algae outbreak.
Big remaining question is “How could suspended sediments in the whole Mekong River easily disappear?” despite the fact that when flowing into Thailand in Chiang Saen district, the river is still full of turbidity from suspended sediments. But after flowing into Lao PDR of Kaeng Pha Dai, Wiang Kaen district and getting back again to Thai-Laos border in Loei’s Chiang Khan district, the Mekong River becomes clear, almost completely free of sediment. Both Thai authorities as well as regional organizations directly in charge have not paid much attention to this phenomenon, including its impacts to the ecosystem and communities during these past 5 years.
The overlapping periods of the clear, sediment-free, Mekong River as well as the Mekong algae bloom phenomenon have continuously been happening after the opening of the Xayaburi dam on October, 29, 2019. The dam is located in Xayaburi province where the Mekong enters Lao PDR, approximately 200 kilometers above Thai northern border in Chiang Khan district. Such period is the beginning of the winter followed by the dry season of every year causing a phenomenon that has never occurred before. This kind of situation normally takes place in March-April, how is the Xayaburi dam related to the phenomenon of clear, sediment-free Mekong River? The communities must find out the answer of such question by themselves.
The Mekong Community Network’s Turbidity Monitoring
An initiative in data checking and tracking the amount of sediment through scientific process by the villagers started in early 2021 using turbidity measuring cylinder (2-inch diameter, 120-centimeter long) as well as Secchi Disk[5] for water turbidity measurement system. There were 10 turbidity monitoring stations (some of them have not currently been activated), namely, the Mekong School in Chiang Rai’s Chiang Khong district; local raft fishing groups of Loei’s Chiang Khan district; Ban Pak Chom, Moo.10 and Ban Khok Wao of Loei’s Pak Chom district; Ban Muang of Nong Khai’s Sangkhom district; Ban Sam Phong (Songkhram River) of Nakhon Phanom’s Sri Songkhram district; Ban Na Tham in That Phanom district, Nakhon Phanom province; Ban Pong Kham of Mukdahan’s Wan Yai district; Ban Khok San Tha of Amnat Charoen’s Chanuman district and Ban Samrong of Ubon Ratchathani’s Pho Sai district. Among these stations, the Mekong School is the only station located above the Xayaburi dam, the others are all in the northeastern region downstream of the dam. There are, however, also many large tributaries flowing into the Mekong which, during the dry season, will not have much effect in terms of quantity and turbidity. Turbidity values are measured in centimeters, the more you can read, it indicates that the water has little turbidity or is very clear. On the other hand, less value indicates that there is a lot of turbidity or little clarity in the water.
Picture 1 Turbidity comparison from February 6 to 20, 2021
The turbidity monitoring has continued until the present day (2024), including when Chinese dams released sediments, during January 18-21, 2024, suddenly causing increase of turbidity with 24, 8, 7 and 14 values respectively. It is an undisputed indication regarding the influence of the Xayaburi dam on retaining sediments when measuring the turbidity at Chiang Khan station during the next 5 days: January 24-26, 2024[6], the values got higher at 98, 96, 108 and 109 centimeters respectively as seen in Picture 2.
Picture 2 Turbidity comparison from January 16 to 27, 2024 between the Mekong School and the raft of local fishing group.
In conclusion, the Mekong turbidity monitoring system of the community network comparing upstream and downstream of the Xayaburi dam found that the turbidity value has evidently decreased. It was a confirmation of the hypothesis that the Xayaburi dam is the main factor causing suspended sediments coming from Chiang Khong district to settle out until the water becomes clear when flowing downstream during the period of low water.
Sediments/Suspensions Measurement by Government Agencies
The report on “The Project to Study and Monitor Cross-Border Environmental Impact of the Mainstream Mekong River Hydropower Projects”[7] of fiscal year 2014, 2015, 2016 by the Department of Water Resource and year 2020 by the Office of the National Water Resources showed that there were suspension measurements both upstream and downstream areas of the Xayaburi dam in Thailand. The table below points out what happened when the measured values were taken to find the percentage of increase or decrease in the amount of suspension using Chiang Saen and Chiang Khan as the main reference stations. If in any year, there is no information from Chiang Saen station, the data from other stations upstream of the Xayaburi dam would be used instead.
Table Percentage of increase/decrease in the amount of suspension between the measurement at Chiang Saen/Chiang Khong and Chiang Khan stations.
| Percentage of increase/decrease in the amount of suspension between the measurement at Chiang Saen/Chiang Khong and Chiang Khan 1/Ban Khok Ngio stations | Fiscal year 2020 | Fiscal year 2016 | Fiscal year 2015 | Fiscal year 2014 | |
| December 2020 | February 2021 | December 2016-January 2017 | Less water 2015 | Less water 2014 | |
| -77.53 | -98.77 | -32.14 | -11.4 | -14.16 | |
| Decrease 77.53% | Decrease 98.77% | Decrease 32.14% | Decrease 11.4% | Decrease 14.16% | |
Results of the comparison of suspension amount at Chiang Khan station before and after the construction of the Xayaburi dam, especially during the low water and dry seasons, found that the amount of suspension had obviously decreased after the Xayaburi dam was built. In December 2020 and February 2021, the average values decreased by -77.53% and -98.77% respectively compared to before the opening of the said dam. In 2014, 2015 and 2016, the proportion of the Mekong suspension at Chiang Khan station decreased by -10.76%, -7.83% and -32.14% respectively.
The information from the report on “The Project to Study and Monitor Cross-Border Environmental Impact of the Mainstream Mekong River Hydropower Projects” by the Department of Water Resource as well as the Office of the National Water Resources can therefore be applied in the form of an increase or decrease of suspension proportions. It pointed out that the amount of suspension has decreased significantly with no longer need to claim that there is no minimum standard value for analyzing the impacts.
Turbidity measurement by the Mekong River Commission
Sediment changes in the Mekong River were studied generally by the MRC[8] showing the amount changing of the Mekong sediment caused by dams’ water storage on both the Mekong River and its tributaries. Ubon Ratchathani’s Khong Chiam district was used as a division point for calculating the amount of sediment. It was found in 2007 that the amount of sediment in the Mekong River was 106.33 million tons per year, accounting for 71% of the sediment volume at the Mekong Delta in Vietnam. Compared to the year 2020, China already built all 11 dams and Lao’s Xayaburi dam was completed, the volume decreased to only 31.38 million tons a year or as much as 70%. And if considering merely sediments from China in 2007, it was equal to 86.75 million tons per year and decreased to 15.03 million tons per year or 83% in 2020. The MRC’s study also indicated that Lao’s Mekong dams (Xayaburi and Don Sahong) have trapped up to 10.2 million tons of sediment per year in 2020.
The amount of sediment decreased by as much as 70% in this past 13 years, it has created an erosion power against the banks; river bed as well as sub-ecosystems of the Mekong River. Don (island); Haad (beach) and channel have been explicitly changed in different areas, there was also soil erosion where the Mekong aquatic plants such as Krai-nam (Willow-leaved water croton) and Wah-nam (Syzygium cumini) depending on and using as a source of nutrients, making a lot of them died. In addition, the amount of sediment deposited on farmland along the Mekong riverbanks has obviously decreased, nutrients that used to be fish’s food have also disappeared.
Table Quantity of the Mekong sediments comparing the year 2007 and 2020.
| Sediment Quantity | Year 2007 | Year 2020 | Note |
| Sediment quantity at the Mekong River mouth | 150 | 160 | Unit: million tons |
| Sediment quantity at Khong Chiam | 106.33 | 31.38 | Unit: million tons |
| Sediment quantity at Khong Chiam decreased between the year 2007 and 2020 | 74.95 | Unit: million tons | |
| Sediment quantity from China | 86.75 | 15.03 | Unit: million tons |
| Sediment quantity from China decreased between the year 2007 and 2020 | 71.72 | Unit: million tons | |
Conclusion
Clean electricity gained from the process that have caused the Mekong River clear and sediment-free therefore creates a myth about “cleanliness” making the society confused. Such cleanliness hides pollution in the Mekong River ecosystem, damage to the ruins of communities and houses of those who had to be evacuated; destruction of the richness of the river ecosystem as well as aquatic life and abundance lost from the decrease of sediment throughout the river are impossible to be assessed. Electricity from dams is therefore not clean energy, but there is a cost to ecosystem; environment; biodiversity as well as community’s way of life. These do not be mentioned and are hidden costs which the ecosystem and communities have to bear forever.
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[1] Montree Chantawong, Mekong Butterfly, March 6, 2024.
[2] ONWR’s press release. March 25, 2020, https://www.bangkokbiznews.com/news/detail/872560
[3] https://www.mrcmekong.org/news-and-events/news/mekong-rivers-aquamarine-hue-likely-to-occur-elsewhere-due-to-low-flows-bringing-possible-risks/
[4] https://www.mrcmekong.org/news-and-events/news/pr002-12022021/
[5] Although turbidity measuring cylinder and Secchi Disk cannot represent total amount of suspended substances or sediments, but the comparison amongst measuring stations in different provinces was used as indicator in this measurement process.
[6] There was no turbidity measurement at the local raft fishing group of Ban Chiang Khan on January 23, 2024.
[7] The Project to Study and Monitor Cross-Border Environmental Impact of the Mainstream Mekong River Hydropower Projects (Fiscal year 2014, 2015, 2016, 2020)
[8] https://www.mrcsummit.org/assets/documents/MRC-IC-Presentations/1a/8e1067dbf9/Ms-Sopheap-Lim_MRCS_MRC-IC-Session-1a_V1.pdf and https://www.mrcmekong.org/assets/Publications/Mekong-sediment-from-the-MRC-Council-Study-Technical-notedocx.pdf
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