The MEKONG is a trans-boundary river in
Southeast Asia . It is the
world's 12th-longest river and the 7th-longest in Asia. Its
estimated length is 4,350 km (2,703 mi), and it drains an area of
795,000 km2 (307,000 sq mi), discharging 475 km3 (114 cu mi) of water
Tibetan Plateau the river runs through China\'s Yunnan
Cambodia , and
Vietnam . In
1995, Laos, Thailand, Cambodia, and
Vietnam established the Mekong
River Commission to assist in the management and coordinated use of
the Mekong's resources. In 1996
Myanmar became "dialogue
partners" of the MRC and the six countries now work together within a
The extreme seasonal variations in flow and the presence of rapids
and waterfalls in the
Mekong make navigation difficult. Even so, the
river is a major trade route between western
China and Southeast Asia.
* 1 Names
* 2 Course
* 3 Drainage basin
* 3.1 Upper basin
* 3.2 Lower basin
* 3.3 Water flow along its course
* 4 River modifications
* 5 Natural history
* 6 Fisheries
* 8 Geology
* 9 History
* 10 Bridges
* 11 Protected areas
* 12 Natural phenomena
* 13 See also
* 14 References
* 15 Further reading
* 16 External links
The English name "Mekong" derives from a contracted form of Thai and
Lao "Mae Nam Khong". In Thai and Lao, mae nam ("mother of water") is
used for any major river and Khong is the proper name. As such, Thai
and Lao locals often refer to it in English as the "River Khong".
Khong itself, however, is an archaic word meaning "river" or "the
river", cognate with Chinese 江 whose
Old Chinese pronunciation has
been reconstructed as /*kˤroŋ/ and which long served as the proper
name of the
Yangtze before becoming a generic word for major rivers.
In Khmer , Mékôngk is itself glossed as "mother of water", from mé
("mother") and taking kôngk as a form of kôngkea ("water"). The
local names for the river include:
* Burmese : မဲခေါင်မြစ်, IPA:
* Chinese: 澜沧江 Láncāng Jiāng(in China),湄公河 Méigōng
hé(Out of China),扎曲 Zā Qū(Tibetan name)
* Khmer : មេគង្គ Mékôngk ,
ទន្លេមេគង្គ Tônlé Mékôngk ,
ទន្លេធំ Tônlé Thum ("Great River").
* Lao : ແມ່ນ້ຳຂອງ, , ນ້ຳຂອງ .
* Thai : แม่น้ำโขง, .
* Tai of Sipsong Panna , น้ำแม่ของ ,
* Tibetan : རྫ་ཆུ་, Wylie : rDza chu, ZYPY : Za qu
* Vietnamese : Sông Mê Kông (IPA: ); Great River (Sông Lớn,
); Nine Dragons River (Sông Cửu Long, ( ).
Mekong rises as the Za Qu and soon becomes known as the Lancang
(Lantsang) in the "Three Rivers Source Area" on the
Tibetan Plateau in
Sanjiangyuan National Nature Reserve ; the reserve protects the
headwaters of, from north to south, the Yellow (Huang He), the Yangtze
, and the
Mekong Rivers. It flows through the Tibetan Autonomous
Region and then southeast into
Yunnan Province, and then the Three
Parallel Rivers Area in the
Hengduan Mountains , along with the
Yangtze to its east and the
Salween River (Nujiang in Chinese) to its
Mekong then meets the tripoint of China,
Laos . From
there it flows southwest and forms the border of
about 100 kilometres (62 mi) until it arrives at the tripoint of
Myanmar, Laos, and
Thailand . This is also the point of confluence
Ruak River (which follows the Thai–
Myanmar border) and
the Mekong. The area of this tripoint is sometimes termed the Golden
Triangle , although the term also refers to the much larger area of
those three countries that is notorious as a drug producing region.
From the Golden Triangle tripoint, the
Mekong turns southeast to
briefly form the border of
Laos with Thailand.
"Khon Pi Long, a series of rapids along a 1.6-kilometre section of
Mekong River dividing Chiang Rai and Bokeo province in Laos. The
name of the rapids means where the ghost lost its way". It then turns
east into the interior of Laos, flowing first east and then south for
some 400 kilometres (250 mi) before meeting the border with Thailand
again. Once more, it defines the Laos-
Thailand border for some 850
kilometres (530 mi) as it flows first east, passing in front of the
capital of Laos,
Vientiane , then turns south. A second time, the
river leaves the border and flows east into
Laos soon passing the city
Pakse . Thereafter, it turns and runs more or less directly south,
Phnom Penh the river is joined on the right bank by the river and
lake system the
Tonlé Sap . When the
Mekong is low, the
Tonle Sap is
a tributary; water flows from the lake and river into the Mekong. When
Mekong floods, the flow reverses; the floodwaters of the Mekong
flow up the Tonle Sap.
Immediately after the Sap River joins the
Mekong by Phnom Penh, the
Bassac River branches off the right (west) bank. The
Bassac River is
the first and main distributary of the Mekong; thus, this is the
beginning of the
Mekong Delta. The two rivers, the Bassac to the west
Mekong to the east, enter
Vietnam very soon after this. In
Vietnam, the Bassac is called the Hậu River (Sông Hậu or Hậu
Giang); the main, eastern, branch of the
Mekong is called the Tiền
River or Tiền Giang. In Vietnam, distributaries of the eastern
(main, Mekong) branch include the
Mỹ Tho River , the
Ba Lai River ,
Hàm Luông River , and the
Cổ Chiên River .
Phou si The confluence of the
Nam Ou river in
Mekong Basin can be divided into two parts: the "upper Mekong
Tibet of China, and the "lower
Mekong basin" from Yunnan
China to the South
China Sea . From the point where
it rises to its mouth, the most precipitous drop in the
in the upper
Mekong basin, a stretch of some 2,200 km (1,400 mi).
Here, it drops 4,500 metres (14,800 ft) before it enters the lower
basin where the borders of Thailand, Laos, China, and
together in the Golden Triangle . Downstream from the Golden Triangle,
the river flows for a further 2,600 km (1,600 mi) through Laos,
Cambodia before entering the South
China Sea via a
complex delta system in
The upper basin makes up 24 percent of the total area and contributes
15-20 percent of the water that flows into the
Mekong River. The
catchment here is steep and narrow. Soil erosion has been a major
problem and approximately 50 percent of the sediment in the river
comes from the upper basin.
Yunnan Province in China, the river and its tributaries are
confined by narrow, deep gorges. The tributary river systems in this
part of the basin are small. Only 14 have catchment areas that exceed
1,000 km2 (390 sq mi), yet the greatest amount of loss of forest cover
in the entire river system per square kilometer has occurred in this
region due to heavy unchecked demand for natural resources. In the
south of Yunnan, in Simao and
Xishuangbanna Prefectures, the river
changes as the valley opens out, the floodplain becomes wider, and the
river becomes wider and slower.
Major tributary systems develop in the lower basin. These systems can
be separated into two groups: tributaries that contribute to the major
wet season flows, and tributaries that drain low relief regions of
lower rainfall. The first group are left bank tributaries that drain
the high rainfall areas of Laos. The second group are those on the
right bank, mainly the Mun and Chi rivers, that drain a large part of
Laos lies almost entirely within the lower
Mekong basin. Its climate,
landscape and land use are the major factors shaping the hydrology of
the river. The mountainous landscape means that only 16 percent of the
country is farmed under lowland terrace or upland shifting cultivation
. With upland shifting agriculture (slash and burn), soils recover
within 10 to 20 years but the vegetation does not. Shifting
cultivation is common in the uplands of northern
Laos and is reported
to account for as much as 27 percent of the total land under rice
cultivation. As elsewhere in the basin, forest cover has been
steadily reduced during the last three decades by shifting agriculture
and permanent agriculture. The cumulative impacts of these activities
on the river regime have not been measured. However, the hydrological
impacts of land cover changes induced by the
Vietnam War were
quantified in two sub-catchments of the lower
Mekong River basin.
Loss of forest cover in the Thai areas of the lower basin has been
the highest in all the lower
Mekong countries over the past 60 years.
Khorat Plateau , which includes the Mun and Chi tributary
systems, forest cover was reduced from 42 percent in 1961 to 13
percent in 1993. Although this part of northeast
Thailand has an
annual rainfall of more than 1,000 mm, a high evaporation rate means
it is classified as a semi-arid region. Consequently, although the Mun
and Chi Basins drain 15 percent of the entire
Mekong basin, they only
contribute six percent of the average annual flow. Sandy and saline
soils are the most common soil types, which makes much of the land
unsuitable for wet rice cultivation. In spite of poor fertility,
however, agriculture is intensive. Glutinous rice, maize and cassava
are the principal crops. Drought is by far the major hydrological
hazard in this region. Floating homes on the
Mekong enters Cambodia, over 95 percent of the flows have
already joined the river. From here on downstream the terrain is flat
and water levels rather than flow volumes determine the movement of
water across the landscape. The seasonal cycle of changing water
Phnom Penh results in the unique "flow reversal" of water
into and out of the Great Lake via the
Tonle Sap River. Phnom Penh
also marks the beginning of the delta system of the
Mekong River. Here
the mainstream begins to break up into an increasing number of
In Cambodia, wet rice is the main crop and is grown on the flood
plains of the Tonle Sap, Mekong, and Bassac (the
distributary known as the Hậu in Vietnam) Rivers. More than half of
Cambodia remains covered with mixed evergreen and deciduous broadleaf
forest, but forest cover has decreased from 73 percent in 1973 to 63
percent in 1993. Here, the river landscape is flat. Small changes in
water level determine the direction of water movement, including the
large-scale reversal of flow into and out of the
Tonle Sap basin from
Mekong delta in
Vietnam is farmed intensively and has little
natural vegetation left. Forest cover is less than 10 percent. In the
Central Highlands of Vietnam, forest cover was reduced from over 95
percent in the 1950s to around 50 percent in the mid-1990s.
Agricultural expansion and population pressure are the major reasons
for land use and landscape change. Both drought and flood are common
hazards in the Delta , which many people believe is the most sensitive
to upstream hydrological change.
WATER FLOW ALONG ITS COURSE
TABLE 1: BASIC DATA ON COUNTRY SHARE OF MEKONG BASIN TERRITORY AND
Area in Basin (km2)
Catchment as % of MRB
Flow as % of MRB
By taking into account hydrological regimes, physiography land use,
and existing, planned and potential resource developments, the Mekong
is divided into six distinct reaches: The
Reach 1: Lancang Jiang or Upper
Mekong River in China. In this part
of the river, the major source of water flowing into the river comes
from melting snow on the
Tibetan plateau . This volume of water is
sometimes called the "
Yunnan component" and plays an important role in
the low-flow hydrology of the lower mainstream. Even as far downstream
as Kratie, the
Yunnan component makes up almost 30 percent of the
average dry season flow. A major concern is that the ongoing and
planned expansion of dams and reservoirs on the
Mekong mainstream in
Yunnan could have a significant effect on the low-flow regime of the
Mekong basin system.
Reach 2: Chiang Saen to
Nong Khai . This reach is
almost entirely mountainous and covered with natural forest, although
there has been widespread slash and burn agriculture. Although this
reach could hardly be described as "unspoiled", the hydrological
response is perhaps the most natural and undisturbed in all the lower
basin. Many hydrological aspects of the lower basin start to change
rapidly at the downstream boundary of this reach.
Nong Khai to
Pakse . The boundary between
Reach 2 and 3 is where the
Mekong hydrology starts to change. Reach 2
is dominated in both wet and dry seasons by the
Reach 3 is increasingly influenced by contributions from the large
left bank tributaries in Laos, namely the
Nam Ngum ,
Nam Theun , Nam
Hinboun, Se Bang Fai , Se Bang Hieng , and Se Done Rivers. The Mun
-Chi river system from the right bank in
Thailand enters the
mainstream within this reach.
Pakse to Kratie . The main hydrological contributions to the
mainstream in this reach come from the
Se Kong ,
Se San , and Sre Pok
catchments. Together, these rivers make up the largest hydrological
sub-component of the lower basin. Over 25 percent of the mean annual
flow volume to the mainstream at Kratie comes from these three river
basins. They are the key element in the hydrology of this part of the
system, especially to the
Tonle Sap flow reversal.
Reach 5: Kratie to
Phnom Penh . This reach includes the hydraulic
complexities of the Cambodian floodplain, the
Tonle Sap and the Great
Lake. By this stage, over 95 percent of the total flow has entered the
Mekong system. The focus turns from hydrology and water discharge to
the assessment of water level, over- bank storage and flooding and the
hydrodynamics that determine the timing, duration and volume of the
seasonal flow reversal into and out of the Great Lake.
Phnom Penh to the South
China Sea . Here the mainstream
divides into a complex and increasingly controlled and artificial
system of branches and canals. Key features of flow behaviour are
tidal influences and salt water intrusion. Every year, 35–50 percent
of this reach is flooded during the rainy season. The impact of road
embankments and similar infrastructure developments on the movement of
this flood water is an increasingly important consequence of
Table 2 summarises the mean annual flows along the mainstream. The
mean annual flow entering the lower
China is equivalent to
a relatively modest 450 mm depth of runoff. Downstream of Vientiane
this increases to over 600 mm as the principal left bank tributaries
enter the mainstream, mainly the
Nam Ngum and Nam Theun. The flow
level falls again, even with the right bank entry of the Mun-Chi
system from Thailand. Although the Mun–Chi basin drains 20 percent
of the lower system, average annual runoff is only 250 mm. Runoff in
the mainstream increases again with the entry from the left bank of
Se Kong from southern
Se San and Sre Pok from
Cambodia. Floating market of Cần Thơ,
Cầu khỉ (monkey bridge) and small nước mắm workshop (fish
sauce) on the bank of
Tiền River (branch of Mekong) in Binh Dai
Ben Tre province , Vietnam.
TABLE 2: LOWER MEKONG MAINSTREAM ANNUAL FLOW (1960 TO 2004) AT
CATCHMENT AREA (KM2)
MEAN ANNUAL FLOW AS
AS % TOTAL MEKONG
Flows at Chiang Saen entering the lower basin from
Yunnan make up
about 15 percent of the wet season flow at Kratie . This rises to 40
percent during the dry season, even this far downstream. During the
wet season, the proportion of average flow coming from
decreases downstream of Chiang Saen, from 70 percent to less than 20
percent at Kratie. The dry season contribution from
Yunnan is much
more significant. The major portion of the balance comes from Laos,
which points to a major distinction in the low-flow hydrology of the
river. One fraction comes from melting snow in
Tibet and the
rest from over-season catchment storage in the lower basin. This has
implications for the occurrence of drought conditions. For example, if
runoff from melting snow in any given year is very low, then flows
Nong Khai would be lower.
In a large river system like the Mekong, seasonal flows can be quite
variable from year to year. Although the pattern of the annual
hydrograph is fairly predictable, its magnitude is not. The average
monthly flows along the mainstream are listed in Table 3, providing an
indication of their range and variability from year to year. At Pakse
, for example, flood season flows during August would exceed 20,000
cubic metres per second nine years out of ten, but exceed 34,000 m3/s
only on year in ten.
Mekong Mainstream monthly discharge, 1960-2004 (m3/s).
There is little evidence from the last 45 years of data of any
systematic changes in the hydrological regime of the Mekong.
Hydropower in the Mekong River Basin
Mekong is already heavily dammed, with many more dams planned and
China has already built eight hydropower dams on
Mekong mainstream since 1995. As of November 2016,
China has five
more under construction, and another 11 planned or proposed.
two dams under construction on the mainstream, and another seven
planned or proposed;
Cambodia has two planned or proposed. The Mekong
is the fastest growing large river basin in the world in terms of
In December 2016, the Thai cabinet of Prime Minister Prayut
Chan-o-cha agreed "in principle" with a plan to dredge stretches of
Mekong and demolish rocky outcrops that are hindrances to easy
navigation. The international Lancang-
Mekong River navigation
improvement plan for 2015-2025, conceived by China, Myanmar, Lao, and
Thailand, aims to the make the river more navigable for 500-tonne
cargo ships sailing the river from
Luang Prabang , a
distance of 890 kilometres.
China has been the driving force behind
the demolition plan as it aims to expand trade in the area with larger
cargo ships. The plan is split into two phases. The first phase, from
2015-2020, involves a survey, a design, and an assessment of the
environmental and social impacts of the project. These have to be
approved by the four countries involved, China, Laos, Myanmar,
Thailand. The second phase (2020-2025) involves navigational
improvements from Simao in
China to 243 border posts in
Myanmar, a distance of 259 km.
Extirpated from most of its pan-Asian range, Cantor\'s giant
softshell turtle can still be found along a stretch of the
Cambodia (Khmer called "Kanteay")
Mekong basin is one of the richest areas of biodiversity in the
world. Only the Amazon boasts a higher level of biodiversity. 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 new
species were described from the region, including 29 fish species
previously unknown to science, two new bird species, 10 reptiles, five
mammals, 96 plants, and six new amphibians. Between 1997 and 2015, an
average of two new species per week were discovered in the region.
Mekong Region contains 16 WWF
Global 200 ecoregions, the greatest
concentration of ecoregions in mainland Asia.
No other river is home to so many species of very large fish. The
biggest include three species of
Probarbus babs, which can grow up to
1.5 m (4.9 ft) and weigh 70 kg (150 lb), the giant freshwater
stingray (Himantura polylepis, syn. H. chaophraya), which can reach at
least 5 m (16 ft) in length and 1.9 m (6.2 ft) in width, the giant
pangasius (Pangasius sanitwongsei), giant barb (Catlocarpio siamensis)
and the endemic
Mekong giant catfish (Pangasianodon gigas). The last
three can grow up to about 3 m (9.8 ft) in length and weigh 300 kg
(660 lb). All of these have declined drastically because of dams,
flood control, and overfishing.
One species of freshwater dolphin , the
Irrawaddy dolphin (Orcaella
brevirostris), was once common in the whole of the lower
Mekong but is
now very rare, with only 85 individuals remaining.
Among other wetland mammals that have been living in and around the
river are the smooth-coated otter (Lutra perspicillata) and fishing
cat (Prionailurus viverrinus).
Siamese crocodile (Crocodylus siamensis) occurs in
small isolated pockets within the northern Cambodian and Laotian
portions of the
Mekong River. The saltwater crocodile (Crocodylus
porosus) once ranged from the
Mekong Delta up the river into Tonle Sap
and beyond but is now extinct in the river, along with being extinct
in all of
Vietnam and possibly even Cambodia.
Fish Farming on
Mekong branch - Song Tien,
Đồng Tháp prov.,
Aquatic biodiversity in the
Mekong River system is the second highest
in the world after the Amazon . The
Mekong boasts the most
concentrated biodiversity per hectare of any river.
The commercially valuable fish species in the
Mekong are generally
divided between "black fish", which inhabit low oxygen, slow moving,
shallow waters, and "white fish", which inhabit well oxygenated, fast
moving, deeper waters. People living within the
Mekong River system
generate many other sources of food and income from what are often
termed "other aquatic animals" (OAAs) such as freshwater crabs,
shrimp, snakes, turtles, and frogs.
OAAs account for about 20 percent of the total
Mekong catch. When
fisheries are discussed, catches are typically divided between the
wild capture fishery (i.e., fish and other aquatic animals caught in
their natural habitat), and aquaculture (fish reared under controlled
conditions). Wild capture fisheries play the most important role in
supporting livelihoods. Wild capture fisheries are largely open access
fisheries, which poor rural people can access for food and income.
Broadly, there are three types of fish habitats in the Mekong: i) the
river, including all the main tributaries, rivers in the major flood
zone, and the Tonle Sap, which altogether yield about 30 percent of
wild catch landings; ii) rain-fed wetlands outside the
river-floodplain zone, including mainly rice paddies in formerly
forested areas and usually inundated to about 50 cm, yielding about 66
percent of wild catch landings; and iii) large water bodies outside
the flood zone, including canals and reservoirs yielding about four
percent of wild catch landings.
Mekong Basin has one of the world's largest and most productive
inland fisheries. An estimated two million tonnes of fish are
landed a year, in addition to almost 500,000 tonnes of other aquatic
animals. Aquaculture yields about two million tonnes of fish a year.
Hence, the lower
Mekong basin yields about 4.5 million tonnes of fish
and aquatic products annually. The total economic value of the fishery
is between US$3.9 and US$7 billion a year. Wild capture fisheries
alone have been valued at US$2 billion a year. This value increases
considerably when the multiplier effect is included, but estimates
An estimated 2.56 million tonnes of inland fish and other aquatic
animals are consumed in the lower
Mekong every year. Aquatic
resources make up between 47 and 80 percent of animal protein in rural
diets for people who live in the Lower
Mekong Basin. Fish are the
cheapest source of animal protein in the region and any decline in the
fishery is likely to significantly impact nutrition, especially among
the poor. The size of this impact has not been established
It is estimated that 40 million rural people, more than two-thirds of
the rural population in the lower
Mekong basin, are engaged in the
wild capture fishery. Fisheries contribute significantly to a
diversified livelihood strategy for many people, particularly the
poor, who are highly dependent on the river and its resources for
their livelihoods. They provide a principal form of income for
numerous people and act as a safety net and coping strategy in times
of poor agricultural harvests or other difficulties. In
71 percent of rural households (2.9 million people) rely on fisheries
for either subsistence or additional cash income. Around the Tonle Sap
Lake in Cambodia, more than 1.2 million people live in fishing
communes and depend almost entirely on fishing for their livelihoods.
Mekong ferry, Neak Loeung,
Cambodia Slow cruise boats,
For thousands of years the
Mekong River has been an important conduit
for people and goods between the many towns on its banks. Traditional
forms of trade in small boats linking communities continue today,
however the river is also becoming an important link in international
trade routes, connecting the six
Mekong countries to each other, and
also to the rest of the world. The
Mekong is still a wild river and
navigation conditions vary greatly along its length. Broadly,
navigation of the river is divided between upper and lower Mekong,
with the "upper" part of the river defined as the stretch north of the
Khone Falls in southern
Laos and the "lower" part as the stretch below
Narrower and more turbulent sections of water in the upstream parts
Mekong River, coupled with large annual water level variations
continue to present a challenge to navigation. The seasonal variations
in water level directly affect trade in this section of the river.
Volumes of trade being shipped decrease by more than 50 percent,
primarily due to the reduced draughts available during the low water
season (June–January). Despite these difficulties, the
is already an important link in the transit chain between
Bangkok with about 300,000 tonnes of goods shipped via this route each
year. The volume of this trade is expected to increase by 8–11
percent per year. Port infrastructure is being expanded to accommodate
the expected growth in traffic, with new facilities planned for Chiang
In Laos, 50 and 100 DWT vessels are operated for regional trade.
Cargos carried are timber, agricultural products, and construction
Thailand imports a wide variety of products from China,
including vegetables, fruit, agricultural products, and fertilisers.
The main exports from
Thailand are dried longan , fish oil, rubber
products, and consumables. Nearly all the ships carrying cargo to and
from Chiang Saen Port are 300 DWT Chinese flag vessels.
Waterborne trade in the lower
Mekong countries of
Cambodia has grown significantly, with trends in container traffic at
Phnom Penh port and general cargo through
Can Tho port both showing
steady increases until 2009 when a decrease in cargo volumes can be
attributed to the global financial crisis and a subsequent decline in
demand for the export of garments to the US. In 2009,
received a significant boost with the opening of a new deep-water port
Cai Mep in Vietnam. This new port has generated a renewed focus on
Mekong River as a trade route. The
Cai Mep container terminals can
accommodate vessels with a draught of 15.2 m, equivalent to the
largest container ships in the world. These mother vessels sail
directly to Europe or the United States, which means that goods can be
shipped internationally to and from
Phnom Penh with only a single
transshipment at Cai Mep.
As an international river, a number of agreements exist between the
countries that share the
Mekong to enable trade and passage between
them. The most important of these, which address the full length of
the river, are:
* Agreement between
China and Lao PDR on Freight and Passenger
Transport along the Lancang–
Mekong River, adopted in November 1994.
* Agreement on the Cooperation for the Sustainable Development of
Mekong River Basin, Article 9, Freedom of Navigation, 5 April
1995, Chiang Rai.
* Hanoi Agreement between
Cambodia and Viet Nam on Waterway
Transportation, 13 December 1998.
* Agreement between and among the Governments of the Laos, Thailand,
Vietnam for Facilitation of Cross border Transport of Goods and
People, (amended at Yangon, Myanmar), signed in Vientiane, 26 November
* Agreement on Commercial
Navigation on Lancang–
Mekong River among
the governments of China, Laos,
Myanmar and Thailand, adopted at
Tachileik, 20 April 2000.
Phnom Penh Agreement between
Vietnam on the Transit
of Goods, 7 September 2000.
* New Agreement on Waterway Transportation between
Cambodia, signed in Phnom Penh, 17 December 2009.
The internal drainage patterns of the
Mekong are unusual when
compared to those of other 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 homogenous 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. These complex
drainage systems have developed in a setting where the underlying
geological structure is heterogeneous and active, and is the major
factor controlling the course of rivers and the landscapes they carve
The elevation of the
Tibetan Plateau during the Tertiary period was
an important factor in the genesis of the south-west monsoon , which
is the dominant climatic control influencing the hydrology of the
Mekong Basin. Understanding the nature and timing of the elevation of
Tibet (and the Central Highlands of Vietnam) therefore helps explain
the provenance of sediment reaching the delta and the
Tonle Sap Great
Lake today. Studies of the provenance of sediments in the
reveal a major switch in the source of sediments about eight million
years ago (Ma) . From 36 to 8 Ma the bulk (76 percent) of the
sediments deposited in the delta came from erosion of the bedrock in
the Three Rivers Area . From 8 Ma to the present, however, the
contribution from the Three Rivers Area fell to 40 percent, while that
from the Central Highlands rose from 11 to 51 percent. One of the most
striking conclusions of provenance studies is the small contribution
of sediment from the other parts of the
Mekong basin, notably the
Khorat Plateau, the uplands of northern
Laos and northern Thailand,
and the mountain ranges south of the Three Rivers area.
The last glacial period came to an abrupt end about 19,000 years ago
(19 ka ) when sea levels rose rapidly, reaching a maximum of about 4.5
m above present levels in the early
Holocene about 8 ka. At this time
the shoreline of the South
China Sea almost reached
Phnom Penh and
cores recovered from near
Angkor Borei contained sediments deposited
under the influence of tides, and salt marsh and mangrove swamp
deposits. Sediments deposited in the
Tonle Sap Great Lake about this
time (7.9–7.3 ka) also show indications of marine influence,
suggesting a connection to the South
China Sea. Although the
hydraulic relationships between the
Mekong and the
Tonle Sap Great
Lake systems during the
Holocene are not well understood, it is clear
that between 9,000 and 7,500 years ago the confluence of the Tonle Sap
Mekong was in proximity to the South
The present river morphology of the
Mekong Delta developed over the
last 6,000 years. During this period, the delta advanced 200 km over
the continental shelf of the South
China Sea, covering an area of more
than 62,500 km2. From 5.3 to 3.5 ka the delta advanced across a broad
embayment formed between higher ground near the Cambodian border and
uplands north of
Ho Chi Minh City
Ho Chi Minh City . During this phase of its
development the delta was sheltered from the wave action of long-shore
currents and was constructed largely through fluvial and tidal
processes. At this time the delta was advancing at a rate of 17–18
m per year. After 3.5 ka, however, the delta had built out beyond the
embayment and became subject to wave action and marine currents. These
deflected deposition south-eastwards in the direction of the Cà Mau
Peninsula , which is one of the most recent features of the delta.
For much of its length the
Mekong flows through bedrock channels,
i.e., channels that are confined or constrained by bedrock or old
alluvium in the bed and riverbanks. Geomorphologic features normally
associated with the alluvial stretches of mature rivers, such as
meanders , oxbow lakes , cut-offs, and extensive floodplains are
restricted to a short stretch of the mainstream around
downstream of Kratie where the river develops alluvial channels that
are free of control exerted by the underlying bedrock.
Mekong basin is not normally considered a seismically active area
as much of the basin is underlain by the relatively stable continental
block. Nonetheless, the parts of the basin in northern
Laos , northern
China do experience frequent earthquakes and
tremors. The magnitude of these earthquakes rarely exceeds 6.5 on the
Richter magnitude scale
Richter magnitude scale and is unlikely to cause material damage.
A map of 1715, incorrectly showing the
Chao Praya River as a branch
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
Chenla state around the 5th century. The
Khmer empire of
Angkor was the last great Indianized state in the region. From around
the time of the fall of the Khmer empire, the
Mekong was the front
line between the emergent states of Siam and Tonkin (North Vietnam),
Laos and Cambodia, then on the coast, torn between their
The first European to encounter the
Mekong was the Portuguese Antonio
de Faria in 1540. A European map of 1563 depicts the river, although
even by then little was known of the river upstream of the delta.
European interest was sporadic: the Spanish and Portuguese mounted
some missionary and trade expeditions, while the Dutch Gerrit van
Wuysthoff led an expedition up the river as far as
The French invaded the region in the mid-19th century, capturing
Saigon in 1861, and establishing a protectorate over
Cambodia in 1863.
Members of the
Mekong Expedition of 1866-1868
The first systematic European exploration began with the French
Mekong Expedition led by
Ernest Doudard de Lagrée and Francis Garnier
, which ascended the river from its mouth to
Yunnan between 1866 and
1868. Their chief finding was that the
Mekong had too many falls and
rapids to ever be useful for navigation . The river's source was
Pyotr Kuzmich Kozlov in 1900.
From 1893, the French extended their control of the river into Laos,
French Indochina by the first decade of the 20th century.
This lasted until the First and Second
Indochina Wars expelled French
from its former colony and defeated American-supported governments.
Patuxai Gate in
Vientiane , represents important aspects of
traditional architecture in the "
During the wars in
Indochina in the 1970s, a significant amount of
explosives (sometimes, entire barges loaded with military ordnance )
sank in the Cambodian section of the
Mekong (as well as in the
country's other waterways). Besides being a danger for fishermen,
unexploded ordnance also creates problems for bridge and irrigation
systems construction. As of 2013, Cambodian volunteers are being
trained, with the support of the Office of Weapons Removal and
Abatement within the US State Department Bureau of Political-Military
Affairs , to conduct underwater explosive removal.
List of crossings of the Mekong River
Construction of Myanmar–
Laos Friendship Bridge is started on 19
February 2013. The bridge will be 691.6 meters long and have 8.5
meters wide two-lane motorway.
Thai–Lao Friendship Bridge (Thai : สะพาน
มิตรภาพ ไทย-ลาว Saphan Mittaphap Thai-lao)
Nong Khai city with
Vientiane in Laos. The 1,170-metre-long
(3,840 ft) bridge opened on 8 April 1994. It has two 3.5-metre-wide
(11 ft) lanes with a single railway line in the middle. On 20 March
2004, the Thai and Lao governments agreed to extend the railway to Tha
Nalaeng in Laos. This extension has since been completed.
Thai–Lao Friendship Bridge connects
Savannakhet . The two-lane, 12-metre-wide (39 ft), 1,600-metre-long
(5,200 ft) bridge opened to the general public on 9 January 2007.
Thai–Lao Friendship Bridge opened for traffic on 11
November 2011, connecting
Nakhon Phanom Province (Thailand) and
Thakhek (Laos), as part of
Asian Highway 3 . The Chinese and Thai
governments agreed to build the bridge and share the estimated US$33
Thai–Lao Friendship Bridge opened to traffic on 11
December 2013. It links
Chiang Rai Province
Chiang Rai Province ,
Thailand with Ban
Houayxay , Laos.
There is one bridge over the
Mekong entirely within Laos. Unlike the
Friendship Bridges, it is not a border crossing. It is at
Champasak Province . It is 1,380 meters (4,528 ft) long, and was
completed in 2000. 15°6′19.95″N 105°48′49.51″E /
15.1055417°N 105.8137528°E / 15.1055417; 105.8137528
The Kizuna Bridge is in
Cambodia , in the city of Kampong Cham , on
the road linking
Phnom Penh with the remote provinces of Ratanakiri
Mondolkiri , and Laos. The bridge opened for traffic on 11
Prek Tamak Bridge , 40 km north of
Phnom Penh opened in 2010.
Phnom Penh itself has no bridge under construction yet, although two
new bridges have recently opened on the Tonle Sap, and the main bridge
on the highway to Ho Chi Minh was duplicated in 2010.
Another new bridge is to be built at
Neak Leung on the
Phnom Penh to
Ho Chi Minh highway with Japanese government assistance, anticipated
to be opened in 2014.
Vietnam , since the year 2000
Mỹ Thuận Bridge crosses the
first channel—the left, main branch of the Mekong, the Sông Tiền
or Tiền Giang—near
Vĩnh Long and since 2008 Rạch Miễu Bridge
crosses it near Mỹ Tho, between the provinces of Tiền Giang and
Cần Thơ Bridge crosses the second channel—the right, main
distributary of the Mekong, the Bassac (Song Hau). Inaugurated in
2010, it is the longest main span cable-stayed bridge in Southeast
* The headwaters of the
Zadoi County , Qinghai, China, are
Sanjiangyuan National Nature Reserve . The name
Sanjiangyuan means "the sources of the Three Rivers". The reserve also
includes the headwaters of the
Yellow River and the
* The section of the river flowing through deep gorges in Yunnan
Province is part of the Three Parallel Rivers of
Areas and is a UNESCO
World Heritage Site
World Heritage Site .
Tonle Sap Biosphere Reserve in
Cambodia contains the largest
lake in Southeast Asia. It is a UNESCO
Biosphere reserve .
Bank Erosion at Song Tien, a branch of Mekong, in Binh Dai
distr., Ben Tre province, Vietnam.
The low tide level of the river in
Cambodia is lower than the high
tide level out at sea, and the flow of the
Mekong inverts with the
tides throughout its stretch in
Vietnam and up to Phnom Penh. The very
Mekong delta area in
Vietnam is thus prone to flooding,
especially in the provinces of
An Giang and Dong Thap (Đồng Tháp),
near the Cambodian border.
Greater Mekong Subregion
Greater Mekong Sub-region Academic and Research Network
GMS Environment Operations Center
* Sekong River
Mekong River Basin Hydropower
Mekong River Commission
Mekong River massacre 2011 killings on
Stung Sen River
Mekong Expedition of 1866-1868
Fair river sharing
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