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4,909 km Total LengthDrainage Basin: 795,000 km²

The Mekong River (Lancang)

Ancient Appellations: Lancang Jiang (Chinese) • Mae Nam Khong (Thai/Lao) • Mékôngk (Khmer)

Southeast Asia’s mother of waters, sustaining the Tonle Sap reverse-flow flood pulse that powered the agricultural wealth of the Khmer Angkor Empire.

4.0
Source: Lasagongma Spring, Tibetan Plateau, QinghaiMouth: South China Sea Wikidata: Q41179 ↗

Hydrological Influence & Ancient Statecraft

Traversing six nations from Tibetan glaciers to the South China Sea, the Mekong is one of the most biodiverse freshwater rivers on Earth. Its hydrological marvel is the Tonle Sap lake connection: during the monsoon, the Mekong’s surge reverses the flow of the Tonle Sap River, expanding the lake fivefold and depositing fertile silt that fueled the vast hydraulic city of Angkor Wat.

Agricultural Surplus & Flood Pulse Ecology

World-leading wet-rice paddies across the sprawling nine-armed "Cuu Long" (Nine Dragons) delta in Vietnam.

Hydrological Anatomy

  • ✓Unique reverse-flow phenomenon where monsoon floods back up into Tonle Sap Lake
  • ✓Khone Phapheng Falls in Laos, the widest waterfall in the world (over 10 km wide)
  • ✓Extensive inland fisheries supporting the primary protein source for 60 million people
  • ✓Deep freshwater canyon stretches through the Hengduan Mountains of Yunnan

About the Mekong

The Mekong or Mekong River (UK: mee-KONG, US: may-KAWNG) is a transboundary river in East Asia and Southeast Asia. It is the world's twelfth-longest river and the third-longest in Asia with an estimated length of 4,909 km (3,050 mi) and a drainage area of 795,000 km2 (307,000 sq mi), discharging 475 km3 (114 cu mi) of water annually. From its headwaters in the Tibetan Plateau, the river runs through Southwest China (where it is officially called the Lancang River), Myanmar, Laos, Thailand, Cambodia, and southern Vietnam. The extreme seasonal variations in flow and the presence of rapids and waterfalls in the Mekong make navigation difficult, though the river remains a major trade route between Tibet and Southeast Asia. The construction of hydroelectric dams along the Mekong in the 2000s through the 2020s has caused serious problems for the river's ecosystem, including the exacerbation of drought.

Encyclopedic summary adapted from Wikipedia: Mekong (CC BY-SA 4.0).

Mekong in Depth

Course

The Mekong rises as the Za Qu (Tibetan: རྫ་ཆུ་, Wylie: rDza chu, ZWPY: Za qu; Chinese: 扎曲; pinyin: Zā Qū) and soon becomes known as the Lancang River (simplified Chinese: 澜沧江; traditional Chinese: 瀾滄江; pinyin: Láncāng Jiāng, from the Lao kingdom Lan Xang; the characters may also be literally understood as "turbulent green river"). It originates in the "three rivers source area" on the Tibetan Plateau in the Sanjiangyuan National Nature Reserve. The reserve protects the headwaters of (from north to south) the Yellow (Huang He), the Yangtze, and the Mekong rivers.

History

The difficulty of navigating the river has meant that it has divided, rather than united, the people who live near it. The earliest known settlements date to 210 BCE, with Ban Chiang being an excellent example of early Iron Age culture. The earliest recorded civilization was the 1st century Indianised-Khmer culture of Funan, in the Mekong delta. Excavations at Oc Eo, near modern An Giang, have found coins from as far away as the Roman Empire. This was succeeded by the Khmer culture Chenla state around the 5th century. The Khmer empire of Angkor was the last great Indianized state in the region.

Natural history

The Mekong basin is one of the richest areas of biodiversity in the world. Only the Amazon boasts a higher level of bio-diversity. Biota estimates for the Greater Mekong Subregion (GMS) include 20,000 plant species, 430 mammals, 1,200 birds, 800 reptiles and amphibians, and an estimated 850 freshwater fish species (excluding euryhaline species mainly found in salt or brackish water, as well as introduced species). The most species rich orders among the freshwater fish in the river basin are cypriniforms (377 species) and catfish (92 species).

New species are regularly described from the Mekong. In 2009, 145 species previously unknown to science were described from the region, including 29 fish species, 2 bird species, 10 reptiles, 5 mammals, 96 plants, and 6 amphibians.

Geology

The internal drainage patterns of the Mekong are unusual among those of large rivers. Most large river systems that drain the interiors of continents, such as the Amazon, Congo, and Mississippi, have relatively simple dendritic tributary networks that resemble a branching tree. Typically, such patterns develop in basins with gentle slopes where the underlying geological structure is fairly homogeneous and stable, exerting little or no control on river morphology. In marked contrast, the tributary networks of the Salween, Yangtze, and particularly the Mekong, are complex with different sub-basins often exhibiting different and distinct drainage patterns.

Sections adapted from Wikipedia: Mekong (CC BY-SA 4.0).

Mekong: Key Facts

Key facts about Mekong
Average discharge15,000 m³/s
Drainage systemMekong River Watershed
TributariesTha River, Nam Ou, Tonle Sap River, Nam Ngum, Kok River, Ing River, Mun River, Ruak River

Facts from Wikidata Q41179 (CC0).

Dams of the Mekong River

2 dams of the Mekong River, ordered by structural height, with their reservoirs and generating capacity.

Dams of the Mekong River
DamHeightCapacityCompleted
Xiaowan Dam292 m4,200 MW2010
Nuozhadu Dam261.5 m5,850 MW2014

Xiaowan Dam

Arch dam · Yunnan, China

Xiaowan Dam is an arch dam on the Mekong (Lancang) in Yunnan, China, standing 292 m (958 ft) high and completed in 2010. It carries an installed hydroelectric capacity of 4,200 MW. The structure impounds Xiaowan Reservoir.

The Xiaowan Dam (simplified Chinese: 小湾坝; traditional Chinese: 小灣壩; pinyin: Xiǎowān Bà) is an arch dam on the Lancang (Mekong) River in Nanjian County, Yunnan Province in southwest China. The primary purpose of the dam is hydroelectric power generation and it supports a 4,200 MW power station. Constructed between 2002 and 2010 by Huaneng Power International at a cost of ¥32 billion (nearly US$3.9 billion), it is the world's second highest arch dam at 292 m (958 ft). It is also third highest among dams of all types behind Jinping-I and Nurek and the third largest hydroelectric power station in China.

Adapted from Wikipedia: Xiaowan Dam (CC BY-SA 4.0).

Dam type
Arch Dam
Structural height
292 m (958 ft)
Installed capacity
4,200 MW
Impounded river
Mekong (Lancang)
Reservoir
Xiaowan Reservoir
Location
Yunnan, China
Year completed
2010
Height rank
#3 of 115 indexed
Output rank
#17 of 102 indexed
Coordinates
24.7003°, 100.0911°

Notable: World's second-tallest arch dam (292 m), generating clean hydro power from the alpine Upper Mekong.

Among the 115 dams indexed in YearMaps, Xiaowan Dam ranks #3 by structural height, behind Jinping-I Dam (305 m). By installed generating capacity it ranks #17, behind Three Gorges Dam (22,500 MW).

Nearest cities: Baoshan (106 km), Dali (112 km), Chuxiong (151 km).

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More about Xiaowan Dam

Background

The feasibility study for the dam was completed in 1992, with it as part of the Lancang River Project. In 1995 the report was reviewed and approved by the Chinese government. Three years later in 1998, a consortium to fund and construct the dam was organized. In 1999, preliminary construction (roads, bridges, river diversion) began. Official construction on the dam started on 1 January 2002. The river was diverted by November 2003 and concrete pouring began in 2005. The river diversion was closed and the reservoir began to impound in November 2007. The first generator was commissioned in September 2009 and the dam was complete in March 2010. The last of the six generators went operational on 22 August 2010.

Sections adapted from Wikipedia: Xiaowan Dam (CC BY-SA 4.0).

Xiaowan Dam: Key Facts

Key facts about Xiaowan Dam
Crest length902 m

Facts from Wikidata Q83532 (CC0).

Nuozhadu Dam
Image via Wikimedia Commons (author and licence on the file page).

Nuozhadu Dam

Rock-fill Embankment dam · Yunnan, China

Nuozhadu Dam is a rock-fill embankment dam on the Mekong (Lancang) in Yunnan, China, standing 261.5 m (858 ft) high and completed in 2014. It carries an installed hydroelectric capacity of 5,850 MW. The structure impounds Nuozhadu Reservoir.

Nuozhadu Dam (Chinese: 糯扎渡大坝; pinyin: Nuòzhādù Dàbà) is an embankment dam on the Lancang (Mekong) River in Yunnan Province in southwest China. The dam is 261.5 m (858 ft) tall, and creates a reservoir with a normal capacity of 21,749,000,000 m3 (17,632,000 acre⋅ft) at a level of 812 m (2,664 ft) asl. The purpose of the dam is hydroelectric power production along with flood control and navigation. The dam supports a power station with nine generators, each with generating capacity of 650 MW. The total generating capacity of the power station is 5,850 MW. Construction on the project began in 2004; the dam's first generator went online 6 September 2012 and the last generator was commissioned in June 2014. The construction and management of the project was implemented by Huaneng Power International Ltd., which has a concession to build, own and operate hydroelectric dams on China's stretch of the Mekong River.

Adapted from Wikipedia: Nuozhadu Dam (CC BY-SA 4.0).

Dam type
Rock-fill Embankment
Structural height
261.5 m (858 ft)
Installed capacity
5,850 MW
Impounded river
Mekong (Lancang)
Reservoir
Nuozhadu Reservoir
Location
Yunnan, China
Year completed
2014
Height rank
#7 of 115 indexed
Output rank
#12 of 102 indexed
Coordinates
22.6561°, 100.4183°

Notable: Tallest rock-fill embankment dam in China and the largest hydro station on the international Mekong.

Among the 115 dams indexed in YearMaps, Nuozhadu Dam ranks #7 by structural height, behind Jinping-I Dam (305 m). By installed generating capacity it ranks #12, behind Three Gorges Dam (22,500 MW).

Nearest cities: Simao (59 km), Chuxiong (288 km), Yuxi (291 km).

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More about Nuozhadu Dam

Nuozhadu Dam: Key Facts

Key facts about Nuozhadu Dam
Crest length608 m

Facts from Wikidata Q1256524 (CC0).

Mekong River: Quick Answers

Which countries does the Mekong River flow through?
The mapped course of the Mekong River runs through or along China, Myanmar, Laos, Thailand, Cambodia and Vietnam.
Where does the Mekong River begin and end?
Source: Lasagongma Spring, Tibetan Plateau, Qinghai. Mouth: South China Sea (Mekong Delta, Vietnam).
How long is the Mekong River?
About 4,909 km (3,050 miles), draining a basin of about 795,000 km².
What is the tallest dam on the Mekong River?
Xiaowan Dam is the tallest dam recorded on the Mekong River, at 292 m (958 ft), completed in 2010.
Which civilizations grew up along the Mekong River?
Among them: Funan Kingdom, Chenla Kingdom, Khmer Empire (Angkor) and Lan Xang.

Countries Along the River

The main stream from source to mouth, then any country only a tributary or delta branch reaches.

  1. 1China
  2. 2Myanmar
  3. 3Laos
  4. 4Thailand
  5. 5Cambodia
  6. 6Vietnam

Historic Cities on the Banks

Luang PrabangVientianePhnom PenhCan ThoJinghong