Saturday, August 4, 2018

After Xepian-Xe Nam Noy dam in Laos collapsed: More than thousand People missing

See Xepian-Xe Nam Noy dam Google Map

How to donate for dam flood victims in Laos - suggestions by Laotian Times



Read the latest situation update by United Nations in Laos

PRAY FOR LAO PEOPLE!

4.8.2018

Search for missing people still onging. The deputy secretary of Attapeu’s provincial committee, Meenaporn Chaichompoo, has admitted that “we can’t find 1,126 people”, notes The Diplomat. Lao Prime Minister Thongloun Sisoulith admitted it was the worst disaster faced by the small Southeast Asian country in decades. The latest report about the situation in Sanamxay district by UNO.

The eight villages most affected by the flood are all contaminated by Unexploded Ordnance (UXO). At least 94% of the villages in Attapeu province are contaminated by UXO, says Unicef.



31.7.2018

European commission has published a remodelling of the flood wave here


28.7.2018

Lao Government has issued a warning for people living along Nam Ou river near Luang Prabang, reports @PichayadaCNA. It says the water level of Nam Ou 2 dam has reached crisis point and urges local residents to prepare for evacuation. The dam is part of a seven-dam cascade developed by China’s Sinohydro Corp. Warning notice has been issued on Friday (Jul 27) by the Ministry of Natural Resources and Environment as well as the Department of Meteorology and Hydrology. See Nam Ou Hydropower Google Map



Here information by Nam Ou River Basin Hydropower Co LTD.


'It sounded like the sea': Lao villagers, now in a shelter in Sanamxai secondary school recount frightening moment of dam collapse on channelnewsasia.



Latest situation in Sanamxai, Attapeu province:
-11,034 people affected
-3,060 registered in shelters
-at least 131 missing
-at least 19 killed
-6,400 displaced
-Immediate food needs of 96 tonnes a month
According to UN report, read Laos dam collapse affects more than 10,000 people: UN report


27.7.2018

The Laotian prime minister Thonglun Sisoulit said on Wednesday (Jul 25) 131 people are still missing, as channelnewsasia reports. He attributed the collapse of the dam to “heavy rainfall” and “possibly faulty construction” according to rfa.org. Ian Baird, a professor of geography at the University of Wisconsin-Madison and an expert on Laos, told RFA’s Lao Service Wednesday that the project partners should be held responsible for the collapse of the dam, noting that heavy rains should not have been enough to cause the tragedy. “It was caused due to poor management of the reservoir water of the Xe Pian Xe Namnoy Dam. It is the middle of the monsoon rainy season, so heavy rains should be expected during this time of year.” Minister of Energy and Mines, Dr Khammany Inthirath, told the media that the collapse of the Saddle Dam was likely due to substandard construction, as Laotian Times reports.

Dam operator Korea Western Power Co. said one of the auxiliary dams - "Saddle D" - broke under heavy rain. But according to a timeline the firm provided in a report to a South Korean lawmaker and obtained by AFP, it said "11 centimetres of subsidence was found at the centre of the dam" as early as Friday.

At least three thousand people in Laos are still in need of rescue, clinging to trees and sitting on rooftops, after Xe Pian Xe Namnoy dam burst, flooding villages and killing at least 19, reports theguardian.com.

26.7.2018
Situation overview bei Unitar

25.7.2018
Situation overview by Unitar.

24.7.2018
Hundreds of people are missing and an unknown number dead after the Xepian-Xe Nam Noy dam collapsed in south-east Laos, media are reporting. The collapse at the hydroelectric dam in Attapeu province late on Monday sent flash floods through six villages. Lives have been lost, thousands of homes are destroyed and several hundres of people are missing, as jclao.com reports. Sanamxay district governor Bounhome Phommasone told RFA’s Lao Service on July 24 that around 4,000 residents of seven villages in Sanamxay have now been moved to higher ground, with approximately 2,000 taken to the area of district offices and the rest moved to safety in other places.

According to Pichayada P. the following villages were hit by the flashflood: Yai Thae, Hinlad, Mai, Thasengchan, Tha Hin and Samong.

See this video on Facebook of people living along Xe Pian River

The US$1.2 billion dam is part of a project by Vientiane-based Xe Pian Xe Namnoy Power Company, or PNPC, a joint venture formed in 2012 between a Laotian, a Thai and two South Korean companies, according to the project's website.

The main Thai stakeholder in the project, Ratchaburi Electricity Generating Holding, said it had received a report from the dam's operator that a "saddle dam", measuring 770m long and 16m high, had collapsed, reports BBC. A spokesman for SK Engineering & Construction, a South Korean company with a stake in the project, told the BBC a small supply dam - not the main dam - had been partly lost due to "unexpected heavy rainfall".

The dam is a key component of the country’s controversial ambition to become the “battery of Asia” by selling power to its neighbours, reports theguardian.com. Eleven large hydropower dams on the main Mekong River, and 120 tributary dams, are planned over the next 20 years.

According to jclao.com a signed letter from Mr Lee Kang Yeol, Head of the Resettlement Office of Xe-Pian Xe-Namnoy Power Company, has been spread around social media in Laos, warning that part of its dam is likely to break. Reuters reports that an official of SK Engineering & Construction said the company ordered the evacuation of 12 villages as soon as it became clear that the dam would collapse.


Warning dated from Sunday 23th of July

See Instagram pictures of Attapue Xe Pian Xe Namnoy Hydroelectric Power
See Instagram Pictures about Power Intake Xepian Xenamnoy Hydropower Project

Read background about Xepian-Xe Nam Noy dam project: Lao Power for Thailand: New dams on Bolaven Plateau affect the Dong Hua Sao National Biodiversity Conservation Area.
Read about other dam projects: Xayaburi Dam and Don Sahong Dam in Mekong River divide Laos, Cambodia and Vietnam


Maps of Xepian-Xe Nam Noy dam project, published by Xe-Pian Xe-Namnoy Power Co., Ltd.:






Xe Pian Xe Namnoy dam illustration on conpaper.tistory.com


Analysis of XePian-XeNamnoy dam break - what we know so far
The following analysis has been published in Chinese here by author 徐泽平 郑璀莹, translated an rewrited:

Around 20 o'clock on July 23, 2018, the dam break occurred. The Xe-Namnoy reservoir (total storage capacity of 1.043 billion m3) was broken by the D dam with a height of 16 m. The dam flood flooded the Sanamxay area of Attapeu province in southern Laos. Villages. According to the emergency letter issued by the owner PNPC, the media reported that the flood discharge reached 5 billion m3.
The project consists of three dams, Xe-Namnoy (see Youtube), Xe-Pian and Houay Makchanh, five auxiliary dams, water delivery systems and powerhouses with a total installed capacity of 410 MW. The Houay Makchanh reservoir has a controlled drainage area of 81km2. The dam is a concrete overflow dam with a maximum dam height of 8.5m, a dam axis length of 1789.0m and a dam crest elevation of 814.5m. The water is led to the Xe-Pian reservoir through the diversion channel. The Xe-Pian reservoir has a controlled drainage area of 271km2. The dam is a composite dam of concrete gravity dam and clay core wall rockfill dam. The maximum dam height is 48m, the dam axis is 1307.0m long, the dam crest elevation is 799.5m, and the total reservoir capacity is 2000. The Xe-Pian Reservoir is connected to the Xe-Namnoy Reservoir through a 7.96km diversion canal. Xe-Namnoy is a large reservoir with a controlled drainage area of 522km2. The dam is a clay core wall rockfill dam (Fig. 5). The maximum dam height is 73.7m, the dam axis is 1600m long, the dam crest elevation is 792.5m, and the total reservoir capacity is 1.043 billion m3.

The dam that breaked was the D dam (Saddle Dam D) on the southwest side of the Xe-Namnoy Reservoir. The D dam is an earth dam with a dam height of 16m, a dam axis of 770m and a dam roof width of 8m. According to a report received by AFP on the 25th, a South Korean congressman reported that on July 20th, the D dam had "11 cm subsidence in the middle" A spokesperson for the Western Electric Power Company said: "It is unclear why some of the dams have sunken and cracked. But all of this happened in heavy rain." On July 23, the PNPC issued an emergency letter to the government authorities, pointing out that due to the severe heavy rain in the area, the reservoir water overflowed the dam crest of D dam. At 12 noon, the local government ordered the downstream villagers to evacuate. At about 8 o'clock that night, the D dam collapsed, and the reservoir water poured down and flowed westward into the Xe Pian River. Due to the limited capacity of the Xe Pian channel, the floods flow out of the river. Many villages in the Sanamxay area are flooded, including Mai Village, HinLath Village, ThaSengchan Village, Thahintai Village, Sanong Village, Thae Village, Phonsa-ath Village and Nongkhae Village. Among them, Hinlath Village and Mai Village are the most seriously affected.br>
In general, the continuous heavy rainfall caused by the monsoon season and the tropical storm Son-Tinh is the direct cause of flooding and dam failure. The Global Disaster Alerting Coordination System (GDACS) issued the Orange Warning for the Tropical Storm in Son-Tinh on July 15, 2018. The affected areas include the Philippines, China, Vietnam and Laos. The Ban Veunkhen hydrological site data, which is not far from the disaster area, shows strong rainfall due to the transit of the Son-Tinh tropical storm on July 20-21. The water level in the rivers increased rapidly and reached its peak on July 24.

As early as July 20, PNPC discovered the structural defects of the D dam dam crest. According to the description in this report, the defects of the dam crest structure are mainly cracks and subsidence. The cracks are mainly longitudinal cracks along the axis of the dam and transverse cracks partially perpendicular to the dam axis. The causes of the crack at the top of the dam may include:

1) The dam body is not densely packed, and the wet deformation of the dam body after the reservoir is stored causes uneven subsidence in the upstream and downstream directions of the dam body, thus showing cracks in the direction of the dam line at the dam crest.
2) Due to the problem of the material or construction quality of the dam, the central part of the dam (the bottom of the saddle mouth) and the bank slope are unevenly deformed, so that the crack perpendicular to the axis of the dam is formed. Usually, the crack is mainly distributed in the abutment part.
3) There are defects in the seepage control measures of the dam body. Under the condition of high water level, there is osmotic damage inside the dam body, and the dam top collapses after the fine particles in the dam body are lost.

From the management perspective, Laos has a tropical and subtropical monsoon climate, and the rainy season is from May to October. A clear flood control plan should be formulated to timely dispatch operations according to changes in water and rain conditions to avoid flooding and dams. These specific operational schedules are still unknown. However, according to the emergency letter and the scene photos issued by the PNPC on July 23, the reservoir was full and the water flow over the D dam, eventually this was leading to the collapse of the D dam.

For earth-rock dam projects, one of the most important causes of collapse is external erosion damage caused by the diffuse roof, and the other is the internal erosion damage caused by seepage. For earth-rock dam projects, in addition to ensuring the reliability of the dam structure design and construction quality, the capacity and reliability of the flood discharge facilities should be highly valued.

The project investor was PNPC (Xe-Pian Xe-Namnoy Power Company) and construction began in February 2013. It was planned to start production in 2019. PNPCs shareholders are Korea SK Construction Co., Ltd. (SKEC, holding 26%), Thailand Ratchaburi Power Generation Company (RATCH, holding 25%), Korea West Power (KOWEPO, holding 25%) and Laos Holding State-owned Enterprise (LHSE, 24%).This joint venture has been formed in March 2012. PNPC invested about US$1.02 billion. PNPC has signed a franchise agreement with the Lao government. After the beginning of the commercial operation of the power station, it will be franchised for 27 years. 370MW of electricity will be sold to the Thai Electric Power Company (EGAT), and 40MW of electricity will be sold to Laos Power Company (EDL).


Background about Hydropower dams in Laos:

Laos - the Battery of Asia: Hydropower Dams and Consequences


See also Google Map Mekong River Hydropower and Dams


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Location: Attapeu, Laos

1 comment:

  1. SimonJuly 26, 2018 at 2:31 AM

    thank you for this post, I've also posted satellite images here http://www.cesbio.ups-tlse.fr/multitemp/?p=13872

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