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Physical features
The Mekong River drains more than 313,000 square miles
(810,000 square km) of land, stretching from the Plateau
of Tibet to the South China Sea. Among Asian rivers,
only the Yangtze and Ganges have larger minimum flows.
The contrast between the physical conditions that
prevail above and below the Mekong’s descent from the
Yunnan highlands divide it into two major parts. The
upper Mekong flows 1,215 miles (1,955 km) through a
long, narrow valley comprising roughly one-fourth of the
total area, cutting through the mountains and plateaus
of southwestern China. The lower Mekong, below the point
where it forms the border between Myanmar and Laos, is a
stream 1,485 miles (2,390 km) in length draining the
Khorat Plateau of northeastern Thailand, the western
slopes of the Annamese Cordillera in Laos and Vietnam,
and most of Cambodia, before reaching the sea through
the distributary channels of its delta in southern
Vietnam.
Climate and hydrology
The Mekong’s flow comes chiefly from rainfall in its
lower basin, which fluctuates seasonally with the
monsoon winds. In April the flow is ordinarily at its
lowest. In May or June—as the rain-bearing southerly
monsoon winds arrive—the flow begins to increase, with
an especially rapid increase in the eastern and northern
highlands. The Mekong’s highest water levels occur as
early as August or September in the upper reaches and as
late as October in the southern reaches. The
northeasterly monsoon wind, beginning ordinarily in
November in the southern areas, brings dry weather until
May. During the long dry period, rice cultivation is
impossible without irrigation, and the river’s waters
are vital to agricultural production.
Temperatures in the lower Mekong basin are uniformly
warm throughout the year. Daily highs at Phnom Penh
average 89 °F (32 °C), and lows average 74 °F (23 °C).
In the upper basin, temperatures are moderated somewhat
by altitude and generally are lower and exhibit more
seasonal variation than those found farther south.
People
A substantial majority of the people who live along the
Mekong River are engaged in agriculture, and rice is the
major crop. The heaviest population concentrations are
in the delta and on the Khorat Plateau. The small urban
population has been growing rapidly, chiefly through
migration to the capital cities. The peoples of the basin are diverse. Most residents of
the uppermost Mekong Valley are Tibetan. South of the
Tibetan Highlands, the peoples of the river basin fall
into two broad cultural groupings. The hill peoples
subsist mainly through shifting cultivation, and have
traditionally formed small, kin-based social units,
while the lowland peoples, who practice sedentary
agriculture, have formed complex state societies. The
hill peoples speak languages belonging to five different
language families: Tibeto-Burman (including the Yi,
Hani, and Lisu of Yunnan), Tai (including the Shan of
Myanmar and the so-called Black Tai and Red Tai of Laos
and Yunnan), Hmong-Mien (including the Hmong of Laos and
Yunnan), Austronesian, and Mon-Khmer (including the
diverse Montagnard peoples of Vietnam). The lowland
peoples, however, form the majority of the population,
and most belong to one of the dominant ethnic groups of
the region’s nations. These include the Han Chinese of
Yunnan, whose language is distantly related to the
Tibeto-Burman languages, the Lao of Laos and the Thai of
Thailand, both speaking languages in the Tai family, and
the Vietnamese of Vietnam and the Khmer of Cambodia,
Vietnam, and Thailand, both speaking Mon-Khmer
languages. The Cham, a minority lowland people of
Vietnam and Cambodia, speak an Austronesian language.
Mekong Delta
The Mekong Delta covers an area of
67,000 square km in the southernmost region of Vietnam
and is often referred to as the rice bowl of Vietnam as
it produces three harvests per year. The Mekong River
begins its life in Tibet and travels 4,500 km..The Mekong Delta covers an area of 67,000 square km in
the southernmost region of Vietnam and is often referred
to as the rice bowl of Vietnam as it produces three
harvests per year. The Mekong River begins its life in
Tibet and travels 4,500 km through six countries before
eventually splitting into nine tributaries (Cuu Long in
Vietnamese) and flowing into the South China Sea. Because the plains are periodically flooded by the
rising Mekong River, traditional transportation is by
boat, along a vast network of canals. These canals are
the very lifeblood of the Delta and her 15 million
inhabitants. Everything from human cargo to tropical
fruits with exotic names such as Dragon fruit and Longan
(Dragon’s eye) can be found along this complex system
of waterways. A cruise along these canals with their
floating markets always proves to be a fascinating and
rewarding experience for all visitors.
The Bassac Rivers
Bassac River (commonly called Tonle
Bassac) is a distributary of the Mekong River. The river
starts from Phnom Penh and flows south out to the
Vietnamese border near Chau Doc. Bassac River is a
popular entry and exit route for the locals between
Cambodia and Vietnam and is used for transporting goods
between the two countries.
Tonle Sap Lake
Cambodia's Tonle Sap, or Great Lake,
is one of the unique geographical wonders of the world.
It offers visitors insights into the centuries-old
traditions of riparian life and the natural splendor of
the country.
On the banks of the mighty Great Lake and the Tonle Sap
and Mekong Rivers, Khmers have celebrated for over two
hundred years the changing of the river's flow. During
the rainy season the Tonle Sap River reversed direction,
flooding the lake, increasing its size almost tenfold,
making it the largest freshwater body in Southeast Asia.
In the flood season, water engulfs surrounding forests,
regulating agricultural production by ensuring that the
countryside is covered with fresh, fertile silt for rice
cultivation. The rivers and lakes of Cambodia are
truly the lifeline for the largely agrarian and fishing
society. The ancient temples of Angkor depict in
exquisite basrelief detail how the life along the lake
affected all walks of Khmer life. For centuries the
Great Lake has yielded many tons of fish per square mile
and provided the major source of Khmer sustenance.
Moreover, for the astute birdwatcher, the aquatic
habitat attracts thousands of birds and fish-eating
waterfowl who flock to the wetland before the rains
begin in June.
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