Mekong River Basic


The Mekong River (known in Tibet as Dza-chu, China as Lancang Jiang and Thailand as Mae Nam Khong), is a major river in southeastern Asia. It is the longest river in the region. From its source in China's Qinghai Province near the border with Tibet, the Mekong flows generally southeast to the South China Sea, a distance of 4,200 km (2,610 mi). The Mekong crosses Yunnan Province, China, and forms the border between Myanmar (Burma) and Laos and most of the border between Laos and Thailand. It then flows across Cambodia and southern Vietnam into a rich delta before emptying into the South China Sea. In the upper course are steep descents and swift rapids, but the river is navigable south of Louangphrabang in Laos.

The natural resource management issues and priorities differ in each of the countries and the level of development and populations vary significantly. In north-east Thailand, with over 20 million people, the water resources are virtually fully developed and problems are emerging associated with salinisation of arable lands as result of over-clearing of native vegetation and poor irrigation, soil erosion, and declining water quality in the rivers and streams. In Laos, with 5 million people and a much poorer country from a GDP perspective, the water resources are largely undeveloped. Cambodia, with 10 million people, is recovering from decades of war, and in the Mekong delta some 20 million Vietnamese live on some of the most highly productive agricultural land in the world.

In short, the Thai want more water; the Laotions want capital and expertise to develop hydropower for export to Thailand and Vietnam; the Khmers need capital and infrastructure and to secure sustainable fishery resources in the Tonle Sap (Great Lake); and the Vietnamese, while in need of capital for the management of resources, do not want any upstream development to exacerbate salt water intrusion in the Mekong delta during the dry season.

Obviously the water is very important to both countries. To use a metaphor a refrigerator cannot run without the correct refrigerator parts. If you use Jenn-Air parts incorrectly the refrigerator will not work. If you use the correct Jenn-Air parts the refrigerator will be happy. Finding a way to place the right parts at certain points of the river will make the citizens of both countries happy.

Special feature - The Tônlé Sap

The Tônlé Sap is a shallow lake in western Cambodia which is part of the Mekong River system. It is the largest lake of Southeast Asia and is fed by numerous streams. During the dry season it drains by the Tônlé Sap River southeast to the Mekong River. During the wet monsoon season of June to November, the high waters of the Mekong River reverse the flow of the Tônlé Sab River and increase the size of the lake from 2,600 to 10,400 sq km (about 1,000 to 4,020 sq mi). When the high waters of the Mekong River recede, the flow reverses. This natural mechanism provides a unique and important balance to the Mekong River down stream of the lake and ensures a flow of fresh water during the dry season into the Mekong delta in Vietnam which buffers the intrusion of salt water from the South China Sea into the rich agricultural lands of the delta.


Normal Flow Wet Season (Reverse flow into the Tônlé Sap) Receding Flow During Dry Season

Fact Sheet


4,200 km (2,610 mi)


China, Myanmar (Burma), Thailand, Laos, Cambodia and Vietnam

Basin population

60 Million

Country population total

242 Million

Per Capita GDP

Varies from US$ 2,565 (Thailand) to US$ 265 (Cambodia)


Irrigation, fisheries, power generation, transportation, industrial and domestic supply

Primary Legal Agreement

Agreement on the Cooperation for the Sustainable Development of the Mekong River Basin, Chiang Rai, Thailand, 5 April 1995 - (Thailand, Laos, Cambodia and Vietnam)

Institutional arrangements

Mekong River Commission (Thailand, Laos, Cambodia and Vietnam)

Primary Legal Agreement

The primary international legal agreement on the Mekong River is entitled "Agreement on the Cooperation for the Sustainable Development of the Mekong River Basin", which was signed in Chiang Rai, Thailand on 5 April 1995 between Thailand, Laos, Cambodia and Vietnam.

Institutional Arrangements

The primary Institution which has been established by the countries which are signatories to the Mekong Agreement is the Mekong River Commission (MRC). For notes on the MRC and how it functions, follow this link. Also see the Mekong Links Pagefor further information and a link to the MRC.


The Mekong system is extremely complex and effects the lives of some 60 million people, many of whom are amongst the poorest in the world. There are many demands made on the river - to provide water for industrial and agricultural development, to sustain subsistence fishing, for transport, to maintain delicate ecological and hydrological balances... Inevitably there are conflicting demands made on the resource and very different views as to how the water should (or should not) be used. The riparian governments, working independently and together through such structures as the Mekong River Commission have a variety of plans for the development of the region, as do community groups, different stakeholders, local and international NGOs, private investment and construction interests etc. For greater detail of the various plans, views and perspectives, see the Mekong Links Page.

Country Information


Qinghai & Yunnan provinces, China







1,115,000 sq km (about 430,400 sq mi);

676,552 sq km (261,218 sq mi).

513,115 sq km
(198,115 sq mi)

236,800 sq km
(91,400 sq mi)

181,035 sq km
(69,898 sq mi)

331,690 sq km
(128,066 sq mi)

Average Annual Precipitation


Tenasserim Coast 5,000 mm (200 in)

Mandalay 760 mm (about 30 in)

Bangkok 1,400 mm (56 in)

Songkhla 2,540 mm (100 in)

1,780 mm (about 70 in)

1,400 mm (about 55 in) central plain

3,800 mm (150 in) in the mountains

Hanoi 1,680 mm (66 in)

Ho Chi Minh City 1,980 mm (78 in)



(1990 estimate)


(1998 estimate)


(1998 estimate)


(1998 estimate)


(1998 estimate)


(1998 estimate)

Population Density


70 persons per sq km (181 per sq mi)

117 persons per sq km (303 per sq mi)

(1998 estimate)

22 persons per sq km (58 per sq mi)

63 persons per sq km (162 per sq mi)

230 persons per sq km (595 per sq mi)

(1998 estimate)

Urban/Rural Breakdown


27% Urban

73% Rural

(1997 estimate)

21% Urban

79% Rural

(1997 estimate)

24% Urban

76% Rural

(1997 estimate)

20% Urban

80% Rural


20% Urban

80% Rural

(1997 estimate)

Gross Domestic Product


US$41.4 billion


US$153.9 billion


US$1.8 billion


US$3 billion


US$24.8 billion

(1997 estimate)

Per capita GDP
(per year)


US$ 875

US$ 2,565

US$ 342

US$ 265

US$ 326