Mekong Delta

The Mekong Delta (Vietnamese: Đồng bằng Sông Cửu Long "Nine Dragon river delta"), also known as the Western Region (Vietnamese: Miền Tây or the South-western region (Vietnamese: Tây Nam Bộ) is the region in southwestern Vietnam where the Mekong River approaches and empties into the sea through a network of distributaries. The Mekong delta region encompasses a large portion of southwestern Vietnam of 39,000 square kilometres (15,000 sq mi). The size of the area covered by water depends on the season.

The Mekong Delta has been dubbed as a "biological treasure trove". Over 1,000 animal species were recorded between 1997 and 2007 and new species of plants, fish, lizards, and mammals has been discovered in previously unexplored areas, including the Laotian rock rat, thought to be extinct.

History

The Mekong Delta was likely inhabited long since prehistory; the empires of Funan and Chenla maintained a presence in the Mekong Delta for centuries. Archaeological discoveries at Óc Eo and other Funanese sites show that the area was an important part of the Funan kingdom, bustling with trading ports and canals as early as in the first century AD and extensive human settlement in the region may have gone back as far as the 4th century BC. Angkor Borei is a site in the Mekong Delta that existed between 400 BC-500 AD. This site had extensive maritime trade networks throughout Southeast Asia and with India, and is believed to have possibly been the ancient capital to the Kingdom of Funan.

River delta

A river delta is a landform that forms from deposition of sediment carried by a river as the flow leaves its mouth and enters slower-moving or standing water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rarely) another river that cannot transport away the supplied sediment.

Despite a popular legend, this use of the word delta was not coined by Herodotus.

Formation

River deltas form when a river carrying sediment reaches either (1) a body of standing water, such as a lake, ocean, or reservoir, (2) another river that cannot remove the sediment quickly enough to stop delta formation, or (3) an inland region where the water spreads out and deposits sediments. The tidal currents also cannot be too strong, as sediment would wash out into the water body faster than the river deposits it. Of course, the river must carry enough sediment to layer into deltas over time. The river's velocity decreases rapidly, causing it to deposit the majority, if not all, of its load. This alluvium builds up to form the river delta. When the flow enters the standing water, it is no longer confined to its channel and expands in width. This flow expansion results in a decrease in the flow velocity, which diminishes the ability of the flow to transport sediment. As a result, sediment drops out of the flow and deposits. Over time, this single channel builds a deltaic lobe (such as the bird's-foot of the Mississippi or Ural river deltas), pushing its mouth into the standing water. As the deltaic lobe advances, the gradient of the river channel becomes lower because the river channel is longer but has the same change in elevation (see slope).

Mekong

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 457 km³ (110 cu mi) of water annually.

From the Tibetan Plateau the river runs through China's Yunnan province, Burma, Laos, Thailand, 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 China and Burma (Myanmar) became "dialogue partners" of the MRC and the six countries now work together within a cooperative framework.

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.

Names

In English the river is called the "Mekong River", derived from "Mae Nam Khong", a term of both Thai and Lao origin. In the Lao-Thai toponymy, "rivers" translates to "mother of water", signalled by the prefix "mae", meaning "mother", and "nam" for water. In the Mekong's case, Mae Nam Khong means "Khong, The mother of water". Many Northern Thai and Laos locals refer to it as the "River Khong". Such is the case with the Mae Nam Ping in Chiang Mai which is known as the "Ping River". The Tonle Sap in Cambodia is a similar example – where Tonle translates as "great lake" or "great river", making the Tonle Sap River an unnecessary repetition of what is in fact the "Sap River". In Khmer language, Mékôngk means "Mother of water" translated as Mé "Mother" and kôngk for kôngkea "water".