Hydropower or water power is power derived from the energy of falling water or fast running water, which may be harnessed for useful purposes. Since ancient times, hydropower from many kinds of watermills has been used as a renewable energy source for irrigation and the operation of various mechanical devices, such as gristmills, textile mills, trip hammers, dock cranes, domestic lifts, ore mills. A trompe, which produces compressed air from falling water, is sometimes used to power other machinery at a distance. In the late 19th century, hydropower became a source for generating electricity. Cragside in Northumberland was the first house powered by hydroelectricity in 1878 and the first commercial hydroelectric power plant was built at Niagara Falls in 1879. In 1881, street lamps in the city of Niagara Falls were powered by hydropower. Since the early 20th century, the term has been used exclusively in conjunction with the modern development of hydroelectric power. International institutions such as the World Bank view hydropower as a means for economic development without adding substantial amounts of carbon to the atmosphere, but dams can have significant negative social and environmental impacts.
In India, water wheels and watermills were built as early as the 4th century BC, although records of that era are spotty at best. In the Roman Empire, water-powered mills produced flour from grain, were used for sawing timber and stone. In China and the rest of the Far East, hydraulically operated "pot wheel" pumps raised water into crop or irrigation canals; the power of a wave of water released from a tank was used for extraction of metal ores in a method known as hushing. The method was first used at the Dolaucothi Gold Mines in Wales from 75 AD onwards, but had been developed in Spain at such mines as Las Médulas. Hushing was widely used in Britain in the Medieval and periods to extract lead and tin ores, it evolved into hydraulic mining when used during the California Gold Rush. In the Middle Ages, Islamic mechanical engineer Al-Jazari described designs for 50 devices, many of them water powered, in his book, The Book of Knowledge of Ingenious Mechanical Devices, including clocks, a device to serve wine, five devices to lift water from rivers or pools, though three are animal-powered and one can be powered by animal or water.
These include an endless belt with jugs attached, a cow-powered shadoof, a reciprocating device with hinged valves. In 1753, French engineer Bernard Forest de Bélidor published Architecture Hydraulique which described vertical- and horizontal-axis hydraulic machines. By the late nineteenth century, the electric generator was developed by a team led by project managers and prominent pioneers of renewable energy Jacob S. Gibbs and Brinsley Coleberd and could now be coupled with hydraulics; the growing demand for the Industrial Revolution would drive development as well. Hydraulic power networks used pipes to carry pressurized water and transmit mechanical power from the source to end users; the power source was a head of water, which could be assisted by a pump. These were extensive in Victorian cities in the United Kingdom. A hydraulic power network was developed in Geneva, Switzerland; the world-famous Jet d'Eau was designed as the over-pressure relief valve for the network. At the beginning of the Industrial Revolution in Britain, water was the main source of power for new inventions such as Richard Arkwright's water frame.
Although the use of water power gave way to steam power in many of the larger mills and factories, it was still used during the 18th and 19th centuries for many smaller operations, such as driving the bellows in small blast furnaces and gristmills, such as those built at Saint Anthony Falls, which uses the 50-foot drop in the Mississippi River. In the 1830s, at the early peak in the US canal-building, hydropower provided the energy to transport barge traffic up and down steep hills using inclined plane railroads; as railroads overtook canals for transportation, canal systems were modified and developed into hydropower systems. Technological advances had moved the open water wheel into an enclosed water motor. In 1848 James B. Francis, while working as head engineer of Lowell's Locks and Canals company, improved on these designs to create a turbine with 90% efficiency, he applied scientific principles and testing methods to the problem of turbine design. His mathematical and graphical calculation methods allowed the confident design of high-efficiency turbines to match a site's specific flow conditions.
The Francis reaction turbine is still in wide use today. In the 1870s, deriving from uses in the California mining industry, Lester Allan Pelton developed the high efficiency Pelton wheel impulse turbine, which utilized hydropower from the high head streams characteristic of the mountainous California interior. A hydropower resource can be evaluated by its available power. Power is a function of volumetric flow rate; the head is the energy per unit weight of water. The static head is proportional to the difference in height. Dynamic head is related to the velocity of moving water; each unit of water can do an amount of work equal to its weight times the head. The power available from falling water can be calculated from the flow rate and density of water, the height of fall, the local acceleration due to gravity: W ˙ o u t =
Vientiane Province is a province of Laos, located in the northwest of the country. As of 2015 the province had a total population of 419,090 people. Vientiane Province is a large province, covering an area of 15,927 square kilometres with 10 districts in mid north-western Laos; the province borders Luang Prabang Province to the north, Xiangkhouang Province to the northeast, Bolikhamxai Province to the east, Vientiane Prefecture and Thailand to the south, Xaignabouli Province to the west. The principal towns are Muang Phôn-Hông. Several kilometres to the south of Vang Vieng is one of Nam Ngum. Much of this area the forests of the southern part, are under the Phou Khao Khouay National Bio-Diversity Conservation Area; the principal rivers flowing through the province are the Nam Song River, Nam Ngum River and the Nam Lik River. In the mid-16th century, Vientiane under King Setthathirat's rule became prosperous, it became a major centre of many wats were built. In 1989, the province was split into two halves — the Vientiane Prefecture containing the city Vientiane itself, the remaining province.
Since 2000, tourism in the region has rocketed, with many thousands visiting Vientiane and Vang Vieng every year. In recent years, new investment has gone into the suburbs of Vientiane; the great Laotian epic, the Phra Lak Phra Lam, claims that Prince Thattaradtha founded the city when he left the legendary Lao kingdom of Muong Inthapatha Maha Nakhone because he was denied the throne in favor of his younger brother. Thattaradtha founded. One day, a seven-headed Naga told Thattaradtha to start a new city on the eastern bank of the river opposite Maha Thani Si Phan Phao; the prince called this city Chanthabuly Si Sattanakhanahud. Contrary to the Phra Lak Phra Ram, most historians believe that the city of Vientiane was an early Khmer settlement centered around a Hindu temple, which the Pha That Luang would replace. Khmer princes ruling Say Fong were known to have made pilgrimages to the shrine near Vientiane. In the 11th and 12th centuries, the time when the Lao and Thai people are believed to have entered Southeast Asia from Southern China, the few remaining Khmers in the area were either killed, removed, or assimilated into the Lao civilization, which would soon overtake the area.
In 1354, when Fa Ngum founded the kingdom of Lan Xang, Vientiane became an important administrative city though it was not made the capital. King Setthathirath established it as the capital of Lan Xang in 1563, to avoid a Burmese invasion. In the following several centuries Vientiane's position was not stable; when Lan Xang fell apart in 1707, it became an independent Kingdom of Vientiane. In 1779, it was made a vassal of Siam; when King Anouvong tried to assert himself as an independent kingdom, raised an unsuccessful rebellion, it was obliterated by Siamese armies in 1827. The city was burned to the ground and was looted of nearly all Laotian artifacts, including Buddha statues and people; the Siamese routed Anouvong and razed the city leaving only the Wat Si Saket in good shape, shifting all people. Vientiane was in great disrepair and disappearing into the forest, when the French arrived in 1867, it passed to French rule in 1893. It became the capital of the French protectorate of Laos in 1899.
The French rebuilt the city and rebuilt or repaired Buddhist temples such as Pha That Luang, Haw Phra Kaew, left many colonial buildings behind. By a decree signed in 1900 by Governor-General Paul Doumer, the province was divided into four muang, these being Borikan, Patchoum and Vientiane. Two years earlier, men from these four muang were responsible for building a house for the first administrator of Vientiane, Pierre Morin. During World War II, Vientiane fell with little resistance and was occupied by Japanese forces, under the command of Sako Masanori. On 9 March 1945 French paratroopers arrived, "liberated" the Vientiane on April 24, 1945; as the Laotian Civil War broke out between the Royal Lao Government and the Pathet Lao, Vientiane became unstable. In August 1960, Kong Le insisted that Souvanna Phouma, become Prime Minister. In mid-December, General Phoumi seized the capital, overthrew the Phouma Government, installed Boun Oum as Prime Minister. In mid-1975, Pathet Lao troops moved towards the city and American personnel began evacuating the capital.
On August 23, 1975, a contingent of 50 Pathet Lao women, symbolically "liberated" the city. In December 2, 1975, the communist party of the Pathet Lao took over Vientiane and defeated the Kingdom of Laos which ended the Laotian Civil War, but the ongoing Insurgency in Laos began in the jungle, with the Pathet Lao fighting the Hmongs, Royalist-in-exile and the Right-wings. In the 1950s and 1960s during the French-Indo China War and Vietnam War, thousands of refugees arrived in the province. By 1963, some 128,000 at arrived Hmong people from Xiengkhouang Province; some 150,000 more arrived in the early 1970s. Many of the refugees arrived. In 1989, the province was split into two parts, the Vientiane Prefecture, which contains the capital and the remaining area, the Vientiane Province. In late 2006, 13 ethnic Khmu Christians were arrested in the village of Khon Kean. One was released in April 2007, on May 16, nine others were released after being held at
A dam is a barrier that stops or restricts the flow of water or underground streams. Reservoirs created by dams not only suppress floods but provide water for activities such as irrigation, human consumption, industrial use and navigability. Hydropower is used in conjunction with dams to generate electricity. A dam can be used to collect water or for storage of water which can be evenly distributed between locations. Dams serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions; the earliest known dam is the Jawa Dam in Jordan, dating to 3,000 BC. The word dam can be traced back to Middle English, before that, from Middle Dutch, as seen in the names of many old cities; the first known appearance of dam occurs in 1165. However, there is one village, mentioned in 1120; the word seems to be related to the Greek word taphos, meaning "grave" or "grave hill". So the word should be understood as "dike from dug out earth".
The names of more than 40 places from the Middle Dutch era such as Amsterdam and Rotterdam bear testimony to the use of the word in Middle Dutch at that time. Early dam building took place in the Middle East. Dams were used to control the water level, for Mesopotamia's weather affected the Tigris and Euphrates rivers; the earliest known dam is the Jawa Dam in Jordan, 100 kilometres northeast of the capital Amman. This gravity dam featured an 9-metre-high and 1 m-wide stone wall, supported by a 50 m-wide earth rampart; the structure is dated to 3000 BC. The Ancient Egyptian Sadd-el-Kafara Dam at Wadi Al-Garawi, located about 25 km south of Cairo, was 102 m long at its base and 87 m wide; the structure was built around 2800 or 2600 BC as a diversion dam for flood control, but was destroyed by heavy rain during construction or shortly afterwards. During the Twelfth Dynasty in the 19th century BC, the Pharaohs Senosert III, Amenemhat III and Amenemhat IV dug a canal 16 km long linking the Fayum Depression to the Nile in Middle Egypt.
Two dams called Ha-Uar running east-west were built to retain water during the annual flood and release it to surrounding lands. The lake called "Mer-wer" or Lake Moeris is known today as Birket Qarun. By the mid-late third millennium BC, an intricate water-management system within Dholavira in modern-day India was built; the system included 16 reservoirs and various channels for collecting water and storing it. One of the engineering wonders of the ancient world was the Great Dam of Marib in Yemen. Initiated somewhere between 1750 and 1700 BC, it was made of packed earth – triangular in cross section, 580 m in length and 4 m high – running between two groups of rocks on either side, to which it was linked by substantial stonework. Repairs were carried out during various periods, most important around 750 BC, 250 years the dam height was increased to 7 m. After the end of the Kingdom of Saba, the dam fell under the control of the Ḥimyarites who undertook further improvements, creating a structure 14 m high, with five spillway channels, two masonry-reinforced sluices, a settling pond, a 1,000 m canal to a distribution tank.
These extensive works were not finalized until 325 AD and allowed the irrigation of 25,000 acres. Eflatun Pınar is a Hittite spring temple near Konya, Turkey, it is thought to be from the time of the Hittite empire between the 15th and 13th century BC. The Kallanai is constructed of unhewn stone, over 300 m long, 4.5 m high and 20 m wide, across the main stream of the Kaveri river in Tamil Nadu, South India. The basic structure dates to the 2nd century AD and is considered one of the oldest water-diversion or water-regulator structures in the world, still in use; the purpose of the dam was to divert the waters of the Kaveri across the fertile delta region for irrigation via canals. Du Jiang Yan is the oldest surviving irrigation system in China that included a dam that directed waterflow, it was finished in 251 BC. A large earthen dam, made by Sunshu Ao, the prime minister of Chu, flooded a valley in modern-day northern Anhui province that created an enormous irrigation reservoir, a reservoir, still present today.
Roman dam construction was characterized by "the Romans' ability to plan and organize engineering construction on a grand scale." Roman planners introduced the then-novel concept of large reservoir dams which could secure a permanent water supply for urban settlements over the dry season. Their pioneering use of water-proof hydraulic mortar and Roman concrete allowed for much larger dam structures than built, such as the Lake Homs Dam the largest water barrier to that date, the Harbaqa Dam, both in Roman Syria; the highest Roman dam was the Subiaco Dam near Rome. Roman engineers made routine use of ancient standard designs like embankment dams and masonry gravity dams. Apart from that, they displayed a high degree of inventiveness, introducing most of the other basic dam designs, unknown until then; these include arch-gravity dams, arch dams, buttress dams and multiple arch buttress dams, all of which were known and employed by the 2nd century AD. Roman workforces were the first to build dam bridges, such as the Bridge of Valerian in Iran
Laos the Lao People's Democratic Republic referred to by its colloquial name of Muang Lao, is a socialist state and the only landlocked country in Southeast Asia. Located at the heart of the Indochinese peninsula, Laos is bordered by Myanmar and China to the northwest, Vietnam to the east, Cambodia to the southwest, Thailand to the west and southwest. Present-day Laos traces its historic and cultural identity to the kingdom of Lan Xang Hom Khao, which existed for four centuries as one of the largest kingdoms in Southeast Asia. Due to Lan Xang's central geographical location in Southeast Asia, the kingdom became a popular hub for overland trade, becoming wealthy economically as well as culturally. After a period of internal conflict, Lan Xang broke off into three separate kingdoms—Luang Phrabang and Champasak. In 1893, it became a French protectorate, with the three territories uniting to form what is now known as the country of Laos, it gained independence in 1945 after Japanese occupation, but was recolonised by France until it won autonomy in 1949.
Laos became independent with a constitutional monarchy under Sisavang Vong. Shortly after independence, a long civil war began, which saw the communist resistance, supported by the Soviet Union, fight against, the monarchy and a number of military dictatorships, supported by the United States. After the Vietnam War ended in 1975, the Communist Pathet Lao movement came to power, seeing the end to the civil war. During the first years of Communist rule, Laos was dependent on military and economic aid supported by the Soviet Union until its dissolution in 1991. In 2018, the country had the fourth highest GDP per capita in Indochina, after Singapore and Thailand. In the same year, the country ranked 139th on the Human Development Index, indicating medium development. Laos is a member of the Asia-Pacific Trade Agreement, Association of Southeast Asian Nations, East Asia Summit and La Francophonie. Laos applied for membership of the World Trade Organization in 1997, it is a one-party socialist republic espousing Marxism–Leninism governed by the Lao People's Revolutionary Party.
The capital and largest city is Vientiane. Other major cities include Luang Prabang and Pakse; the official language is Lao. Laos is a multi-ethnic country, with the politically and culturally dominant Lao people making up about 55 percent of the population in the lowlands. Mon-Khmer groups, the Hmong and other indigenous hill tribes, accounting for 45 percent of the population, live in the foothills and mountains. Laos's strategies for development are based on generating electricity from its rivers and selling the power to its neighbours, namely Thailand and Vietnam, as well as its initiative to become a "land-linked" nation, shown by the construction of four new railways connecting Laos to its neighbours. Laos has been referred to as one of East Asia and Pacific's Fastest Growing Economies by the World Bank, with annual GDP growth averaging 7.8% for the past decade. The English word Laos was coined by the French, who united the three Lao kingdoms in French Indochina in 1893 and named the country as the plural of the dominant and most common ethnic group, which are the Lao people.
In the Lao language, the country's name is "Muang Lao" or "Pathet Lao", both mean "Lao Country". An ancient human skull was recovered from the Tam Pa Ling Cave in the Annamite Mountains in northern Laos. Stone artifacts including Hoabinhian types have been found at sites dating to the Late Pleistocene in northern Laos. Archaeological evidence suggests agriculturist society developed during the 4th millennium BC. Burial jars and other kinds of sepulchers suggest a complex society in which bronze objects appeared around 1500 BC, iron tools were known from 700 BC; the proto-historic period is characterised by contact with Indian civilisations. According to linguistic and other historical evidence, Tai-speaking tribes migrated southwestward to the modern territories of Laos and Thailand from Guangxi sometime between the 8th–10th centuries. Laos traces its history to the kingdom of Lan Xang, founded in the 14th century by a Lao prince Fa Ngum, with 10,000 Khmer troops, took over Vientiane. Ngum was descended from a long line of Lao kings.
He made Theravada Buddhism Lan Xang prospered. Within 20 years of its formation, the kingdom expanded eastward to Champa and along the Annamite mountains in Vietnam, his ministers, unable to tolerate his ruthlessness, forced him into exile to the present-day Thai province of Nan in 1373, where he died. Fa Ngum's eldest son, Oun Heuan, ascended to the throne under the name Samsenthai and reigned for 43 years. Lan Xang became an important trade centre during Samsenthai's reign, but after his death in 1421 it collapsed into warring factions for 100 years. In 1520, Photisarath came to the throne and moved the capital from Luang Prabang to Vientiane to avoid a Burmese invasion. Setthathirat became king in 1548, after his father was killed, ordered the construction of what became the symbol of Laos, That Luang. Setthathirat disappeared in the mountains on his way back from a military expedition into Cambodia and Lan Xang began to decline, it was not until 1637, when Sou
Xiangkhouang is a province of Laos, located in the Xiangkhouang Plateau, north-east of the country. Known as the Principality of Muang Phuan, the present capital of the province is Phonsavan; the population of the province as of the 2015 census is 244,684. Xiangkhouang Province covers an area of 15,880 square kilometres and has a mountainous topography; the province borders Luang Prabang Province to the northwest, Houaphan Province to the northeast, Vietnam to the east, Bolikhamsai Province to the southeast, Vientiane Province to the southwest. Apart from floodplains, the largest area of level land in the country is located in the province's Xiangkhouang Plateau; this area is grassland whose altitude averages 4,250 feet. The country's highest peak, Phou Bia, rises at the southern side of the plateau. Nam Et-Phou Louey is a National Biodiversity Conservation Area in the province which covers a total area of 5,959 km2, overlaps into Houaphan and Luang Prabang provinces. Xiangkhouang Province is one of the main maize producing areas of Laos.
It was bombed during the Vietnam War era. The Plain of Jars site has been proposed for listing as a UNESCO World Heritage Monument. While the origin of the Plain of Jars' people is unknown, the recorded history of Xieng Khouang is interlinked with the Tai Phuan; as an ancient civilization, its prehistory is linked to the enigmatic megalithic stone jars of the Plain of Jars representing burial grounds of ritualistic practices with extended history spread from Angkor period to the Hindu and Buddhist religious impacts. The Tai Phuan or Phuan people are a Buddhist Tai-Lao ethnic group that migrated to Laos from southern China and by the 13th century had formed the independent principality Muang Phuan at the Plain of Jars with Xieng Khouang as the capital, they prospered from the overland trade in metals and forest products with China. In the mid-14th century, Muang Phuan was incorporated into the Lan Xang Kingdom under King Fa Ngum; the Xieng Khouang Plateau has been surmised, based on archaeological finds of Bronze and Iron Age of the period between 500 BC and 500 AD, as the center of trade representing a large area of upland Southeast Asia covering Vietnam, Samrong Sen in Cambodia, the Khorat Plateau in northeast Thailand, Danang City in Laos, the North Cachar Hills of northeastern India.
According to the Pongsawadan Meuang Puan or the Muang Puan Chronicles, the Tai Puan, a Buddhist Tai-Lao ethnic group, are said to be the first people who migrated in the 13th century from China and settled in this province. During the mid 14th century they were subsumed into the Lan Xang Kingdom; the Siamese wars in the 18th and 19th centuries resulted in the Tai Puans' loss of freedom. In subsequent years the Haw invaders from China ravaged the province and Luang Prabang by looting; the Franco-Siamese treaties of In the 1890s came under French colonial rule under Treaty of French Indochina, which extended to a short period beyond World War II. During the Second Indochina War of the 1960s and 70s there was more suffering to the people of the province due to the Laotian Civil War between the Royalist and the Pathet Lao until the 1975 when the Pathet Lao took power. Xiangkhouang was the province most bombed by the USAF airplanes in support of the Royalist forces; as a result of this extended war, Muong Khoun, the original capital of the province suffered much damage due to bombing by the USAF and resulted in shifting of the capital to Phonsavanh.
During this war, most of the temples built in the period from the 16th and 19th century were destroyed except for the Vat Pia Vat temple. The royalist were led by General Vang Pao, born in the province, during the war in the 1960s. Xiangkhouang Province covers an area of 15,880 square kilometres and has a mountainous topography; the province borders Luang Prabang Province to the northwest, Houaphan Province to the northeast, Vietnam to the east, Bolikhamsai Province to the southeast, Vientiane Province to the southwest. The capital is Phonsavan. Xiangkhouang and Vientiane Provinces are part of the Nam Ngum watershed. Apart from floodplains, the largest area of level land in the country is located in the province's Xiangkhouang Plateau; this area is grassland whose altitude averages 4,250 feet. The country's highest peak, Phou Bia, rises at the southern side of the plateau, while the Plain of Jars is in the plateau's center; the province is 400 km northeast of Vientiane. Phu Bia at 2700 m elevation is the highest peak in the province, the highest in Laos.
The capital city is at an elevation of about 1,000 m.s.l with Kham district situated in a low-laying basin at an elevation of about 600 m.s.l. Nam Et-Phou Louey is the National Biodiversity Conservation Area which covers a total area of 5,959 km2 extends within the Xiangkhouang Province apart from the Houaphan, Luang Prabang provinces; the park consists of mountains and hills, with altitude ranging between 336 and 2257 metres above sea level. The area is the source of many rivers, it is named after Phou Louey Mountain. The area has a high level of biodiversity, a number of endangered species including tiger, clouded leopard, Asian golden cat, marbled cat, gaur, Sambar deer, white-cheeked gibbon, sun bear, black bear
The Mekong is a trans-boundary river in Southeast Asia. It is the seventh longest in Asia, its estimated length is 4,350 km, it drains an area of 795,000 km2, discharging 475 km3 of water annually. From the Tibetan Plateau the river runs through China's Yunnan Province, Laos, Thailand and Vietnam. In 1995, Thailand and Vietnam established the Mekong River Commission to manage and coordinate use of the Mekong's resources. In 1996 China and Myanmar became "dialogue partners" of the MRC and the six countries now work together in a cooperative framework; the extreme seasonal variations in flow and the presence of rapids and waterfalls in the Mekong make navigation difficult. So, the river is a major trade route between western China and Southeast Asia; the English name "Mekong" derives from a contracted form of Lao Mae Nam Khong. In Thai and Lao, mae nam is used for any major river and Khong is the proper name; as such and Lao locals 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 and taking kôngk as a form of kôngkea. The local names for the river include: From Thai or Lao: Thai: แม่น้ำโขง, or just'แม่โขง'. Lao: ແມ່ນ້ຳຂອງ, ນ້ຳຂອງ. Tai of Sipsong Panna, น้ำแม่ของ, น้ำของ. Burmese: မဲခေါင်မြစ်, IPA:. Shan: ၼမ်ႉၶွင် or ၼမ်ႉမႄႈၶွင်. Khmer: មេគង្គ Mékôngk, ទន្លេមេគង្គ Tônlé Mékôngk. Chinese: 湄公河. Vietnamese: Sông Mê Kông. From Tibetan: Tibetan: རྫ་ཆུ་, Wylie: rDza chu, ZYPY: Za qu. Chinese: 扎曲. Other: Chinese: simplified Chinese: 澜沧江. ទន្លេធំ Tônlé Thum. Khmuic:,'ŏ̞m̥' means'river' or'water', here it means'river','kʰrɔːŋ̊' means'canal'. So'ŏ̞m̥ kʰrɔːŋ̊' means'canal river'. In the ancient time Khmuic people called it" or" which means'Jiant canal river' or'deep canal river' respectively; the Mekong rises as the Za Qu and soon becomes known as the Lancang in the "Three Rivers Source Area" on the Tibetan Plateau in the Sanjiangyuan National Nature Reserve. It flows through the Tibetan Autonomous Region and southeast into Yunnan Province, the Three Parallel Rivers Area in the Hengduan Mountains, along with the Yangtze to its east and the Salween River to its west.
The Mekong meets the tripoint of China and Laos. From there it flows southwest and forms the border of Myanmar and Laos for about 100 kilometres until it arrives at the tripoint of Myanmar and Thailand; this is the point of confluence between the Ruak River and the Mekong. The area of this tripoint is sometimes termed the Golden Triangle, although the term refers to the much larger area of those three countries, notorious as a drug producing region. From the Golden Triangle tripoint, the Mekong turns southeast to form the border of Laos with Thailand. Khon Pi Long is a series of rapids along a 1.6-kilometre section of the Mekong River dividing Chiang Rai and Bokeo Province in Laos. The name of the rapids means "where the ghost lost its way", it turns east into the interior of Laos, flowing first east and south for some 400 kilometres before meeting the border with Thailand again. Once more, it defines the Laos-Thailand border for some 850 kilometres as it flows first east, passing the capital of Laos, Vientiane turns south.
A second time, the river flows east into Laos soon passing the city of Pakse. Thereafter, it runs more or less directly south, crossing into Cambodia. At Phnom Penh the river is joined on the right bank by the 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 the Mekong floods, the flow reverses: the floodwaters of the Mekong flow up the Tonle Sap. After the Sap River joins the Mekong by Phnom Penh, the Bassac River branches off the right bank; the Bassac River is the main distributary of the Mekong. This is the beginning of the Mekong Delta; the two rivers, the Bassac to the west and the Mekong to the east, enter Vietnam shortly after this. In Vietnam, the Bassac is called the Hậu River. In Vietnam, distributaries of the eastern branch include the Mỹ Tho River, the Ba Lai River, the Hàm Luông River, the Cổ Chiên River; the Mekong Basin can be divided into two parts: the "upper Mekong basin" in Tibet of China, the "lower Mekong basin" from Yunnan downstream from China to the South China Sea.
From the point where it rises to its mouth, the most precipitous drop in the Mekong occurs in the upper Mekong basin, a stretch of some 2,200 km. Here, it drops 4,500 metres before it enters the lower basin where the borders of Thailand, Laos and Myanmar come to
Vang Vieng is a tourist-oriented town in Laos in Vientiane Province about four hours bus ride north of the capital. The town lies on the Nam Song River; the most notable feature of the area is the karst hill landscape surrounding the town. Vang Vieng was first settled around 1353 as a staging post between Luang Vientiane. Named Mouang Song after the body of the deceased King Phra Nha Phao of Phai Naam was seen floating down the river, the town was renamed Vang Vieng during French colonial rule in the 1890s. Significant expansion of the town and its infrastructure occurred during the 1964-73 Vietnam War when the US constructed an air force base and runway, used by Air America; the airstrip was called "Lima site 6". In more recent times, the town has grown due to the influx of backpackers attracted by the opportunities for adventure tourism in a limestone karst landscape. Vang Vieng has become a backpacker-oriented town, with the main street featuring guest houses, restaurants, internet cafes, tour agencies Attractions of the town include inner tubing and kayaking on the Nam Song River, until 2012, was lined with bars selling Beer Lao and Lao-Lao, equipped with rope swings, zip lines and diving into blue lagoon, large decks for socializing.
Vang Vieng locals have organised themselves into a cooperative business association to sell tubing as an activity, in a system in which 1,555 participating households are divided into 10 village units, with each unit taking its turn on a ten-day rotation to rent inner-tubes to the tourists. Thanongsi Sorangkoun, owner of an organic farm in Vang Vieng, says that tubing inadvertently began in 1999 when he bought a few rubber tubes for his farm volunteers to relax on along the river. During the wet season, the river can be a series of rapids. Other activities include rock climbing in the limestone mountains. There are numerous caves, such as Tham Phu Kham half an hour north of Vang Vieng by tuk-tuk or the Tham Non and Tham Jang caves closer to Vang Vieng. A market five kilometres north of town sells Lao textiles, household items, foodstuffs; the town is on Route 13 from Luang Prabang to the capital, Vientiane. It is about eight hours by bus to four hours to Vientiane. Just a short walk from town are many ethnic Lao and Hmong villages, while Vang Vieng Organic Farm is around 4 km north of the town in the village of Phoudindaeng.
There are opportunities for community involvement such as teaching, while it is possible to stay in a house made of mud bricks at the organic farm. Wat Done Hor is the oldest of the five temples in Vang Vieng, built in 1903. Due to the influx of backpackers, Vang Vieng locals have seen drastic changes in their community. In recent years, Vang Vieng has become a stop on the Southeast Asia backpacker circuit and the main street has many guest houses, restaurants, internet cafes and tour agencies. There are concerns that the town is in danger of losing its charm as it becomes full of tourists, mushroom shakes, episodes of Friends, a US sitcom shown in many bars; the New Zealand Herald wrote, "If teenagers ruled the world, it might resemble Vang Vieng". Safety measures for the tubing have been described as "non existent". Tubing combined with heavy drinking has resulted in tourist drownings, it was reported that 22 tourists died on the river in 2011. The Lao government is planning to put more controls on the urban sprawl of Vang Vieng, while the Laos National Tourism Administration has "awareness programs" that ask tourists to "respect and follow the rules, regulations and cultures of the Lao people", while educating local people to maintain the Lao identity, way of life and culture and not imitate tourist behaviour.
Vang Vieng is known to have a problem with drugs, which are accessible to both tourists and local children. Locals have said that tubing and tourism are destroying the town's culture and encouraging crime among children, while loud music destroys the area's tranquility. A report on the future of tourism in Vang Vieng found that many budget tubers were "oblivious to, or uncaring about, the types of social and environmental impact they are associated with." A master plan for Vang Vieng notes that local grievances include pollution, inappropriate behaviour of tourists and environmental damage. Brett Dakin, the author of Another Quiet American, a chronicle of two years in Laos working for the tourist authority, said, "Each time a young Australian woman strolls down the street in a bikini, a bearded American smokes a joint on a guesthouse terrace, or a group of Koreans tumbles drunkenly out of a restaurant, it saps a little more of the essence of a town like Vang Vieng." As of June 2014, the US State Department says that although Laos has a low rate of violent crime, "some tourists have been robbed and sexually assaulted".
Many restaurants in the Vang Vieng area offer menu items "pizzas", "shakes", or "teas" that may contain unknown substances or opiates. These products are advertised as "happy" or "special" items; these unknown substances or opiates can be dangerous, causing serious illness or death. Vang Vieng's hospital recorded 27 tourist deaths in 2011 due to drowning or diving head first into rocks. Most fatalities occur on the same bar-heavy stretch of river. In a 2012 interview with The Guardian newspaper, a senior doctor at the Vang Vieng Hospital, Dr Chit, said the overall figure is higher because "many fatalities are taken straight to Vientiane". In early 2012, two Australian backpackers died within a month. Dr Chit said five to 10 backpackers a day arrive at the local hospital with injuries such as broken bones or inf