The Mekong River rises from the high mountain area of Thanh Hai province and flows approximately 4.909 km through Van Nam province (China), continuing into Myanmar, Thailand, Lao, Cambodia and Viet Nam before emptying into the Eastern Sea. The basin of the Mekong River drains a total land area of 795,000 km2, of which the area in Thailand, Lao, Cambodia and Viet Nam named the Lower Mekong Basin, is over 77 per cent.
The Mekong River is the twelfth-longest in the world and tenth-largest river in term of the total flow (the estimated mean annual flow of the basin as a whole is almost 460 km3, a mean annual discharge is 15,000 m3 per second).
Apart from abundant water resource, the Mekong’s biodiversity is immense, only the Amazon possesses a greater diversity of plants and animals. The Mekong flow feeds many and varied wetlands that perform wide-ranging functions and sustain key social, economic and cultural values. Wetlands also play a vital role in supporting the livelihoods of local people, providing a productive environment for agriculture, aquaculture, capture fisheries, non-fish aquatic goods and tourism revenue. In addition, natural wetlands provide equally important indirect benefits, such as flood mitigation, water store and wastewater treatment.
Mekong River Basin countries form a large section of the Indo-Burma biodiversity hotspot. A broad variety of ecosystems are present in the region, including mixed wet evergreen, dry evergreen, deciduous forests, shrub land and woodlands on karst limestone outcrops, and mangroves. Non-timber forest products provide an important source of income for rural people and supply markets with a vast array of plant and animals products, including foods, medicines and dyes.
The inland fisheries of the Mekong Basin are among the largest in the world. About 850 species of fish have been recorded in the Mekong River Basin and the total yield is about 4 million tons per year. Fisheries provide most people with their primary source of protein.
The Lower Mekong is home to approximately 60 million people. There are over 100 different ethnic groups living within the basin’s boundaries, making it one of the most culturally diverse regions of the world. About 85 per cent of the LMB population live in rural areas and most live below poverty line. Often lacking access to basic government services, people in the LMB are, on average, less well off than their fellow citizens outside the basin.
Mekong farmers have been irrigating farmland long-time ago. Today millions of farmers throughout the basin are producing a second and some a third rice crop using water from about 12,500 irrigation schemes. However, economics are moving farmers away from rice production to other crops but the benefits of increased agricultural production and higher family incomes that come from irrigation must be balanced with the impact of large irrigation schemes on dry season flow, fish migration patterns and soil salination.
The fishery provides a livelihood not just for fishers and their families but for thousands more who are employed full or part time making and selling food products and fishing gear, repairing boats and providing hundreds of related services.
Currently, dams on Mekong tributaries and on the mainstream in China are producing about 13,000 MW, much of it used to power cities and industries outside the basin. The estimated hydropower potential of the LMB is 30,000 MW. More than 3235 MW of hydropower capacity has been installed on tributary systems. A further 3209 MW are currently under construction.
Dams on the Mekong mainstream have been a topic of great controversy for years ago and governments are struggling to balance demands for more power with growing social, economic and environmental concerns. A new and controversial development is the recent shift to consider mainstream hydropower. Some sites are at various stages of feasibility study under agreement with governments.
Navigation, trade and tourism
As it has been for thousands of years, rivers are roads in the Mekong Basin. Except for the Khone Falls area near the Lao-Cambodia border, almost the entire length of the river is navigable for nearly 8 months of the year. The Asian Highway Network is back on track and it will soon be possible to drive between all major cities in the basin. There are currently 7 bridges across the Mekong or its major tributaries and another 6 under construction or in the planning stages.
As the nations bordering the Mekong enter a new era of peaceful cooperation, the pace of development will surely accelerate. It seems that hardly a month goes by without the announcement of another agreement on trade or transport or tourism. As relations warm, trade among the six countries is increasing yearly.
With improved trade relations and better transport links comes increased tourism. The natural beauty, mystique and cultural diversity of the Mekong River Basin are already attracting thousands of visitors and their numbers are expected to increase significantly.
Mekong Basin in Viet Nam
The part of the Mekong River Basin in Viet Nam has a total area of about 71,000 km2, or 8 per cent of the basin area, and 20 per cent of the country’s territory. The part is of rivers, as follows:
In the North, Nam Rom and Nam Nua rivers have a total area of 1,650 km2. The former rises from north Dien Bien district and flows through Dien Bien – Pa Thom City before discharging into Lao territory. The later has an origin in Muong Nha, flows south-north direction before emptying into Lao side. High slopes and waterfalls are common features of these rivers.
In the Midle of Viet Nam, rivers and streams in west Huong Hoa district (Quang Tri province) flow west, discharge into Xe Bang Hieng River (Lao side) before emptying into the Mekong River. These rivers and streams have a total basin area of about 738 km2, of which the largest is Xe Pon River with its basin area in Viet Nam of 310 km2. The Xe Pon is winding complicatedly. It flows est – west, along Viet-Lao border.
The Sekong River rises from Truong Son Mountains (Aso area) in A Luoi district of Thua – Thien – Hue province, where it is called A Sap river. The total basin area of Sekong is about 29,750 km2 in which the part in Viet Nam is 750 km2 (some tributaries of A Sap rise from Kon Tum province).
In the Central Highlands, rivers have their total basin area of about 29,700 km2. The area is upstream of Cambodia while in the South of Viet Nam, the Mekong Delta (Cuu Long) is last downstream of the Mekong River Basin. Rivers in these two areas are described in more details as following.
Mekong Basin in the Central Highlands
In the Central Highlands, Sesan and Srepok are two major branches on the left side of the Mekong River. The total catchment area in Viet Nam of these branches covers 5 provinces of Gia Lai, Kon Tum, Dak Lak, Dak Nong, and Lam Dong.
Sesan originating in the north-east mountains of Gia Lai and Kon Tum provinces, the Sesan River drains a total land area in Viet Nam about 11,450 km2 and flows approximately 252 km with river density of 0.38 km/km2. From the North of Kon Tum, the Sesan flows north – south, continuing to Ialy hydropower scheme, and turns west – south before reaching Vietnam – Cambodia border. The Sesan has an average elevation of 737 m above sea level and an average slope of 14.4 per cent.
Srepok originating in Lam Dong and Dak Lak provinces, the Srepok River drains a total land area in Viet Nam about 12,030 km2 with a river length of 291 km and river density of 0.55 km/km2. The Srepok River has two major branches, namely Krong Kno and Krong Ana. The former rising in a mountain with over 2000 m high, flows approximately 156 km and drains a land area of 3920 km2, and has an average river slope of 6.8 per cent and river density of 0.86 km/km2. The latter flows 215 km and drains a land area of 3960 km2.
According to national population statistics of the country in 2010, over 5.2 million people live in the Central Highlands with an average population density at about 95 people/km2. The figures indicate that the overall population has increased by about 14.8 per cent, and it is significantly higher compared to the country’s rate of 10.3 per cent. About 52 per cent of the region’s population has working age (1.257 million) and about 88 per cent of the population do farming and forestry. There are over 40 different ethnic groups living in the region such as Kinh, Ba Na, Gia Rai, Xo Dang, etc, of which the Kinh comprises about 58 per cent.
The Central Highlands is one of 7 economic zones of Viet Nam. In 2009, the region’s GDP is 33,800 billion VND. Given the natural resources, production of hydropower, agriculture, forestry, and services are major sectors of the region’s economy. Some hydropower stations have been completed and in operation, a few of the others are planned.
Cuu Long Delta
The Mekong Delta begins near Phnom Penh and ends up as a huge fertile flat plain in southern Viet Nam where the largest tributary, the Bassac River, branches away from Mekong River. The Mekong (Tien River) and Bassac (Hau River) split into a number of smaller distributaries, forming an area known as the “Nine Dragons” or “Cửu Long”.
The Mekong Delta in Viet Nam (VNMD) covers an area of some 40,000 km2, or 12 per cent of the country’s land area. It lies with the Vietnamese-Cambodian border in the north-west, the Vam Co River in the northeastern, the East Sea in the south-east and Thailand Bay in the south-west. The VNMD covers 13 provinces and city, namely: Long An, Tien Giang, Dong Thap, Vinh Long, Tra Vinh, Hau Giang, Soc Trang, Ben Tre, An Giang, Kien Giang, Bac Lieu, Ca Mau and Can Tho City.
The annual hydrological regime of the Cửu Long River determined by a major influence – climate. The regime is divided into two distinct seasons. While the flood season occurs from June to December contributing about 90% of annual flow volume, the dry season within 6 months between January and May. Driest flows occur annually in March and April.
The VNMD is very important in Vietnam’s economy. In 2010, rice production of the region reached 21.6 million tons and rice export of about 5 million tons, or 90 per cent of the country. With a sea-shore of over 700 km, the aquaculture land occupies approximately 70 per cent and aquaculture production about 54 per cent of the country. The estimated GDP of VNMD in 2010 achieved almost 161,043 billion VND. The major sectors in the region include agriculture, fishery, and processing industry.
According to national population statistics of the country in 2010, the population estimate of VNMD was over 17 million with a population density of 426 people/km2. About 4 million people live in urban areas. The working age population was about 10.129 million.
In VNMD, Vietnamese people are very interested in river water quality, water quantity, sediment, and fishery. These are important factors influencing contry’s industrialisation, rural and agricultural modernisation.