Salween River

The Salween basin includes about , of which 48 percent is in China, 44 percent in Myanmar, and 8 percent in Thailand. About 89 percent of the annual flow occurs in the monsoon season (mid-May through November), and only 11 percent in the remainder of the year. The population of the Salween basin is estimated at 24 million, or 76 persons/km2. About 10 million people live adjacent or close to the river proper. People of the Salween basin represent a large diversity of ethnic groups. In China, the Salween basin is home to Blang, Derung, Lisu, Nu, Palaung (De'ang), Shan, Tibetan and Wa. In Myanmar, the major ethnic groups include Akha, Lahu, Lisu, Hmong, Kachin, Karen, Karenni, Kokang, Pa'O, Shan and Yao. The various headwater streams flow southwest through high mountain valleys and accumulate in Cona Lake, at . Downstream of the lake, the Tibetan section of the river is called Gyalmo Nagqu, "black river". In Tibet the river flows mostly within Nagqu prefecture. The upper Salween basin includes more than of glaciers. In Yunnan, the Salween is known as the Nujiang () or Nu River, after the indigenous Nu people, but also translating literally to "angry river". (The character is only a homophone, due to Chinese having no phonetic script.) For more than the Salween runs parallel to, and west of the headwaters of the Mekong and Yangtze, separated by high mountain ridges of the Hengduan Mountains. The Gaoligong Mountains west of the Salween form the border between China and Myanmar. Between the Salween and Mekong rivers around the Tibet–Yunnan boundary are the Meili Xue Shan, which include Kawagarbo, the highest peak in the Salween basin at . Much of the river within Yunnan is part of the Three Parallel Rivers of Yunnan Protected Areas, a World Heritage Site. Forming canyons up to deep, this section is often called the "Grand Canyon of the East". Continuing south, the river crosses the Yunnan–Guizhou Plateau via a series of deep canyons broken by wider valleys. In Longling County it is joined by the Kuke River and turns west, entering Myanmar. The total length of the river in China is , not including a short segment along the China–Myanmar border. Lower Salween (Myanmar and Thailand) In Myanmar the Salween river is officially known as Thanlwin; in Shan State, which the river enters immediately upon leaving China, it is also known as Nam Khone. Turning south, the river slices a winding course through the vast upland region known as the Shan Hills. This area is characterized by a complex, broken topography of small mountain ranges, plateaus and cliffs, through which the Salween has cut an extensive series of gorges. As the Salween flows south and descends in elevation, it travels from temperate to subtropical and finally tropical climate zones, with yearly precipitation ranging from in the Shan Hills area. Inle Lake, the second largest lake in Myanmar and a World Biosphere Reserve, drains into the Salween by way of the Pawn River. In Thailand the river is known as Salawin; much of the Thai side of the border is part of Salawin National Park and the Salawin Wildlife Sanctuary. At the south end of the border section it is joined by the northwest-flowing Moei River, which forms the Myanmar–Thailand border south of this point. The Salween emerges from the mountains into the coastal plain near Hlaingbwe Township. Near the coast, annual rainfall is as high as , supporting dense tropical rainforest as well as a productive rice industry. ==Discharge==

Flow regime at Hpa-an Station of Thanlwin River: Monthly flow pattern Thanlwin river at Hpa-an during 2009 to 2013: ==Geology==

The present course of the Salween began to form about 5 million years ago as the Indian subcontinent collided with Asia, resulting in the uplift of the Himalaya mountains and the Tibetan Plateau. Prior to the Himalaya orogeny, what are now the upper Irrawaddy, Salween, Mekong and Yangtze rivers may have all flowed into the Red River, emptying into the South China Sea. The landscape was hilly but not particularly rugged, with average elevations of or less. As the continents converged, a complex jumble of mountains arose, breaking the ancestral Red into different drainage systems, with the Yangtze heading east towards the Pacific, and the Mekong and Salween flowing south into what is now Thailand's Chao Phraya River. About 1.5 million years ago, volcanic activity diverted the Salween west towards the Andaman Sea, roughly creating the modern path of the river. The parallel modern courses of the upper Salween, Mekong and Yangtze are located where the eastern Tibetan Plateau intersects the uplands of the Yunnan–Guizhou Plateau. The mountain ranges separating these rivers are individual terranes (crustal fragments) that accreted separately to the Asian continent – forming a basin and range landscape with drainage running from north to south – then compressed together such that the rivers flow only apart in places. As the mountains continued to rise, the rivers incised into the landscape along parallel fault zones, creating the deep canyons of the present day. The Nujiang fault zone stretches over along the river in Yunnan. The formation of the Himalayas blocked drainage from the Tibetan Plateau south towards the Indian Ocean, forcing drainage north of the mountains east towards the Yangtze river. This east-flowing river, the predecessor of the modern Yarlung Tsangpo river, was repeatedly captured into drainages to the south, finding various routes to the sea via the Red, Mekong, Salween and Irrawaddy rivers. The combined Salween–Yarlung Tsangpo drainage would have been much longer than the modern Salween, stretching an additional west across the Tibetan Plateau. Ultimately the Yarlung Tsangpo was captured by the Brahmaputra River in present-day India. The Salween may once have had additional tributaries above its present source, but due to the uplift of the Himalaya blocking moisture from the Indian Ocean, these tributaries dried up, leaving the numerous terminal lakes scattered across Nagqu today. The Salween carries an estimated 108 to 237 million tonnes of sediment per year. ==Ecology==

The Salween basin is home to thousands of species of plants, with the highest plant diversity found in Yunnan's Three Parallel Rivers region. The Three Parallel Rivers protected areas include the Gaoligongshan National Nature Reserve and the Nu Jiang Reserve within the Salween basin; The Nujiang Lancang Gorge alpine conifer and mixed forests, situated along the Nu River in western Yunnan, span elevations of and range from subtropical broadleaf evergreen to subalpine conifer forests. The rare Taiwania, one of the largest conifers in Asia, is found here along with more than twenty other conifer species. Due to its rugged and inaccessible terrain, this is considered one of the most intact large forest regions in China. The Mekong–Salween divide forms a significant floral and faunal barrier as well as a rain shadow, and has been regarded as a major driver of plant speciation in the region. in Thailand Around the Myanmar–China border, the Salween flows through the Northern Indochina subtropical forests ecoregion, which consists largely of subtropical broad-leaved evergreen forests, with pine forests at higher elevations and tropical forests at the lower margins. Further south in Myanmar and Thailand, the Salween basin includes the Kayah–Karen montane rain forests, where the karst limestone landscape of cliffs, sinkholes and caverns lends itself to a multitude of forest types. Limestone soils host drought deciduous forests, while dipterocarp–dominant tropical forests occur on granitic soils. Montane deciduous forests are widespread in the Shan Hills. Mangrove forests occur in the Salween delta, especially on Bilugyun Island. The Salween has numerous cyprinid species, including the endangered Garra cryptonema and Akrokolioplax bicornis which are endemic to the basin. The Salween basin includes up to 25% of the world's terrestrial animal species.{{cite web ==Economic uses==

Agriculture Along its lower course the Salween sustains both flood and irrigated agriculture. The Salween delta is a major rice-growing area; it is the single most productive agricultural region in the Salween basin and home to over 500,000 people. Rice paddies are highly dependent on the river's annual flooding, bringing deposits of rich sediment. Other crops grown in the Salween basin include maize, wheat, chili, cotton, potatoes, groundnut, sesame, pulses, betel, tea, and various vegetables. Logging and mining Forests along the Salween are prime sources of tropical hardwoods, including teak, pyinkadoe (red ironwood) and padauk (Burmese rosewood). Logging in the Myanmar part of the basin first occurred on a large scale during the British colonial period in the 19th century. Clearcutting has destabilized soils along the river and raised sediment loads. Due to the lack of good roads across most of the basin, the majority of timber is transported via waterways during the rainy season. In China, some forests in western Yunnan were intensively logged until the 1990s, when logging was banned there due to environmental impacts. On the Thai side of the river, illegal logging has been ongoing since the 1990s in Salawin National Park. In Karen State, limestone quarrying for cement production along the river has increased in the 21st century. There is also increasing sand and gravel mining in the lower river. As of 2015 the Myanmar government was seeking international investment in the mining sector, and new policies could lead to considerable increase in mining activity along the river. ==History==

Human presence along the upper Salween River dates to at least 31,000–39,000 years ago. Archeological evidence includes stone tools and animal remains discovered along the river bank in the southeastern Tibetan Plateau. The Mon are some of the earliest inhabitants of the Salween basin within Myanmar, migrating south from China around 3000 BCE, and settling in the Salween delta and adjacent coastal areas. Agriculture was first practiced in the Salween and Irrawaddy basins around the first century BCE. Ancestors of the Karen migrated down the Salween River area from the Tibetan Plateau and northwest China starting around 1000 BCE. Tai peoples, ancestors of the Shan, began moving into the Shan Hills area of the middle Salween from Yunnan around 1000 CE and established multiple independent kingdoms, often known as the Shan States. The Nu people, originating in the Tibetan Plateau, may have inhabited the areas of the Salween (Nu) and Mekong (Lancang) in modern day China as early as 2000 BCE. The Wa people, who today inhabit parts of the Salween basin on both sides of the China–Burma border, migrated south along the river from Tibet around 500–300 BCE. The Lisu people, also originating in Tibet, arrived in Yunnan sometime before 1000 CE. Chinese records begin to mention Lisu in the late Tang dynasty (618–907 CE). The Lisu originally inhabited areas further east in Yunnan, but over centuries they were pushed north and west towards the Salween as more Han people settled in Yunnan. Expansion of empires Martaban (now Mottama) in the Salween Delta was a major trading port on the Maritime Silk Road as early as 200 BCE. By the 6th century CE, the Thaton kingdom (one of the early Mon kingdoms) ruled the Salween Delta and surrounding coasts from the capital of Thaton. From 738–902 CE, the kingdom of Nanzhao controlled Yunnan and parts of northern Burma, with the Salween forming its southwestern boundary with the Burmese Pyu city-states. Tang China had several overland trade routes with Burma via Nanzhao, which it was allied with at times. One route started from Yinsheng (around present-day Jingdong, Yunnan) and headed west, then south along the Salween River, reaching the Indian Ocean at Martaban. Another crossed the Salween around present day Baoshan, heading west towards India. In the 1060s, King Anawrahta expanded the boundaries of the Pagan kingdom (First Burmese Empire) from its origins in the Irrawaddy valley, conquering Thaton and the other Mon kingdoms in the Salween delta. In the late 1100s, King Narapatisithu (Sithu II) conquered most of the Shan States, extending Burmese rule to the western bank of the Salween river from the delta as far north as Yunnan. For almost 500 years, the lower Salween defined the frontier between Burma and the Ayutthaya Kingdom (Siam). In the late 1200s, the Pagan kingdom collapsed after invasions of the Mongol Empire. The Mongols had also conquered the Dali kingdom (Nanzhao's successor). In 1287 the Hanthawaddy kingdom emerged in the Salween and Irrawaddy deltas. Martaban served as the Hanthawaddy capital between 1287 and 1364. Along the mountainous middle reaches of the Salween River, former Shan vassal states regained their independence. Starting around 1380, Ming China annexed Yunnan and conquered some of the eastern Shan states. From 1436-49, Chinese armies crossed the Salween to wage the Luchuan–Pingmian campaigns against the Shan state of Möng Mao. These wars were an expensive failure for the Ming, and triggered tribal uprisings that fragmented Chinese power in the region. The Toungoo dynasty emerged in Burma during the 1500s, conquering much of Southeast Asia by 1565 to create the First Toungoo Empire (Second Burmese Empire). King Tabinshwehti captured and destroyed Martaban in 1541. Under the subsequent rule of Bayinnaung, an 800,000-strong army crossed the Salween in 1548 and invaded Siam. This was the first time Burmese rule had been extended east of the Salween River. Subsequently, Bayinnaung moved north up the Salween, subjugating all the independent Shan states by 1557. These victories were enabled in part by the acquisition of firearms from Dutch and Portuguese traders who first reached these coasts around 1511. European mercenaries also fought in some of these battles. At Martaban, the Portuguese established a trading post, one of the first European settlements in the area. , Tibet In the 1640s, the last years of the Ming dynasty, geographer Xu Xiake explored the Salween River country and determined that the upper Salween, Mekong and Red rivers (previously believed to be part of the same river system) were in fact separate. After the rise of the Qing dynasty China entered a new period of western expansion. In 1717, the Dzungar Khanate conquered Tibet, and China sought to expel them from the region. In 1718, the Qing sent an army but were unsuccessful in reaching Tibet, reaching only as far as the Salween River where they were defeated by Dzungar troops in the Battle of the Salween River. In response, the Qing sent a larger force to Tibet in 1720, driving out the Dzungars and establishing Qing rule of Tibet. As the Qing pushed into Yunnan, the indigenous Lisu people were driven further west, eventually settling along the Salween in and around Nujiang Prefecture. Although China had been expanding into the area since Ming times, the greatest influx of settlers was around 1700 to 1850. At the same time, Tibet was expanding its influence into western Yunnan. Tibetan parties raided down the Salween valley and took slaves from the indigenous Nu and Derung populations, which were not well politically organized and unable to offer much resistance. On the other hand, the Lisu fiercely resisted efforts to take slaves and land. In the 1590s Siam had captured the Tenasserim coast, and the Salween delta again became the border with Burma. For more than a hundred years this remained a disputed area, changing hands several times between the Burmese and Siamese. Burmese rule returned to the Salween delta in the 1750s with the expansion of the Konbaung dynasty. Starting in 1759, Martaban served as a launching point for several invasions of Siam, which led to the collapse of the Ayutthaya kingdom. The Burmese were unable to maintain lasting control over territories east of the river, although Burma regained the Tenasserim coast from Siam in a 1793 treaty. British rule and World War II After the First Anglo-Burmese War in 1824, the Konbaung dynasty ceded coastal areas of Burma to the British Empire, including the whole Tenasserim coast south of the Salween River. Due to its strategic location, Mawlamyine (anglicized as Moulmein) served as the capital of British Burma from 1826 until 1852 and as a gateway for overland trade into Yunnan. It became the center of a lucrative timber industry, particularly in teak. Logs were floated down the Salween River to meet oceangoing ships in Mawlamyine port. Forests in the lower Salween basin were extensively logged until the 1890s. Contemporary British maps labeled the river as "Salween", an anglicization of the Burmese name Thanlwin. At the start of the 20th century, there was still great uncertainty regarding the true sources of the river and how far west it extended into the Himalayas; some believed the upper Brahmaputra River (the Yarlung Tsangpo) might be the true source of the Irrawaddy, Salween or Mekong. In 1935-36, British geographer Ronald Kaulback walked the length of the Salween River from Burma to eastern Tibet, producing some of the first comprehensive maps of the river's course. Kaulback allegedly found giant footprints in the snow while attempting to locate the source of the Salween. His report was one of several that popularized the myth of the Yeti in Europe during the 1930s. During World War II the Japanese Empire invaded Burma, starting at Mawlamyine in January 1942. The Japanese army, numbering 18,000 against 7,000 British defenders, quickly captured Mawlamyine, forcing the British to retreat across the Salween to Martaban. On February 10–11 the Japanese crossed the Salween and the British fled, unprepared for a siege. The Japanese blockaded the Burma Road constructed in 1938 during the Second Sino-Japanese War, forcing the British to transport military supplies to China by air across the eastern Himalayas ("The Hump"). The retreating Allied army (primarily Chinese) stopped the Japanese advance at the Salween River on May 5, 1942. After blowing all the bridges crossing the river, the Chinese took defensive positions on the east bank along a front, at which point the fighting reached a stalemate. From 1944–1945, Allied forces launched the Salween Campaign to retake Burma and reopen the Burma Road. During the initial offensive on May 11, 1944, about 40,000 troops of the Chinese Expeditionary Force (CEF), led by American General Joseph Stilwell and assisted by US army air forces, crossed the Salween on rubber rafts and attacked the Japanese position west of the river. About 17,000–19,000 Chinese and 15,000 Japanese were killed in the resulting battle, from which the Chinese emerged victorious. In the following days, additional CEF troops crossed the river bringing the total to 100,000, before pushing west into Japanese-held territory. The Salween Campaign concluded on January 20, 1945 with the fall of Wanding. By August 1945 the Allies had retaken Burma from the Japanese. 1948–present In 1948, Burma declared independence from the British Empire. Soon afterwards, ethnic minorities in the Salween River region, including the Kachin, Karen, Mon, and Shan, sought independence, with armed conflicts between these groups and the Burmese military continuing to the present day. The Karen National Union and Mon National Defense Organization took control of the lower Salween River valley, including Mawlamyine and Thaton, in September 1948. However, they were soon pushed out, leading to four years of confused fighting. In 1952, a new Karen state (today's Kayin State) was created, with the capital at Hpa-an on the Salween north of Mawlamyine, but the insurgency continued. In 1950 Chinese Nationalist troops invaded Shan State after being defeated by the Communists in the Chinese Civil War, with the aim of creating an independent state from which to retake mainland China. With the help of US forces, the Chinese attempted several times to take land on the west side of the Salween River, but were pushed back by the Burmese army. Although the KMT campaign was unsuccessful, many people of Chinese descent continue to live in the area east of the river. These events contributed to political instability in Shan State. By 1958 several insurgencies had become established in eastern Shan State, including one led by the exiled Communist Party of Burma (CPB, or "White Flag Communists"). This area, part of the Golden Triangle, became a center for illegal opium production during the 1960s. Opium trafficking remains a major source of funding for insurgents. In the 1970s the Burmese and Thai governments began planning for hydroelectric dams on the Salween River, largely within Shan and Karen-majority areas. Starting in 1979 the Electricity Generating Authority of Thailand conducted feasibility studies for hydropower and irrigation diversions on the river. Salween development plans gained momentum in 1988, when the SPDC seized power in Burma and sought cross-border economic development with Thailand and China. That same year, Thai Prime Minister Chatichai Choonhavan presented an economic vision for the Salween border region – from a "battlefield into a marketplace". In addition to the revenues from electricity production, the SPDC saw dam construction as "part of a strategy to remove ethnic armed groups" from the area. In the years following, the military junta stepped up its attacks in the region, destroying villages and forcing over 500,000 Shan, Kachin and Karen refugees to flee the country, mostly to Thailand. The Salween creates a formidable barrier for refugees, due to its wide fast current, and only small wooden boats are available for crossing it. About 150,000 refugees are housed in official camps in Thailand, while hundreds of thousands of more live in illegal camps. Thailand's Salawin National Park was established in 1994. Before that, thousands of refugees had already settled in this area and the adjacent Salawin Wildlife Sanctuary, with more moving in during the years following. The Thai government has made some efforts to remove them, but due to the vast size of the park, enforcement has been difficult. In 1997 a scandal was uncovered in which logs cut on the Thai side of the river were floated across the river to Myanmar, stamped "exported from Burma" and floated back to the Thai side, where officials inspected the "imported" timber and approved their sale. Refugees in camps within the parks were implicated in the scandal and forced to relocate. However, "observers of forced evictions have stated that the eviction of Thai-Karen villagers from forest reserves is not done to protect the forests but so that [illegal] logging activities can continue without hindrance and with fewer witnesses." and the Hatgyi Dam in Karen State. Residents along the Salween River contend the dams would bring no economic benefits locally – as most of the electricity would be exported abroad – while their homes and traditional lands would be flooded with little to no compensation. Local organizations, including the Karen Environmental and Social Action Network (KESAN), have pushed for the establishment of a "Salween Peace Park" that would manage the river's natural resources sustainably via community forests, wildlife sanctuaries, fishery conservation and protected indigenous lands. The park would cover more than along the Salween River and its tributaries in Myanmar. The proposal was inaugurated in December 2018. ==Dams==

Myanmar and Thailand Seven dams have been proposed along the main stem of the Salween in Myanmar and Thailand, with a combined capacity exceeding 20,000 megawatts of electricity – comparable to that of China's Three Gorges Dam. The reservoirs would flood of the total river length in Myanmar, as well as the downstream ends of several tributaries. The Mong Ton or Tasang Dam is the largest of the planned dams. The dam would be high, and produce up to 7,110 megawatts. The reservoir would flood , splitting Shan State nearly in two. The Hatgyi Dam in downstream Kayin State would be smaller, but would have a more significant impact on the river flow. In addition to producing power, the Hatgyi dam would divert some of the Salween flow during certain seasons into the Ping River, part of Thailand's Chao Phraya basin, to benefit agriculture in central Thailand. A smaller alternative to the Salween diversion would be a diversion of the Yuam River (a tributary of the Salween via the Moei River) to the Ping. Salween River is the last undammed major river in South East Asia. The project was initiated by the Chinese firm Yunnan Machinery & Equipment Import & Export Co. (YMEC) and is co-financed by the Chinese state through Hydrochina Corporation. One of the conditions for the dam, whose effect is expected to be in the 1200-1400 MW range, is to transfer at least 50% of the electricity production to China. There are numerous concerns surrounding the potential impact of the dams, particularly the effect on agriculture in the Salween delta due to a reduction in the annual floods and sediment supply that maintain soil fertility. Water would be released based on power demand rather than agricultural needs, potentially causing water shortages and saline intrusion in the delta. Construction plans have raised many concerns regarding social impact, human rights abuses and displacement. China In 2000, China initiated the West-East Power Transfer development scheme, to develop large-scale hydropower dams on its western rivers. The Salween (Nu) River basin within China has an estimated 36,400 megawatts of hydropower potential. The power would be exported to southeastern China, particularly the Guangzhou megalopolis. This included thirteen dams on the mainstem of the Nu, with a total capacity of 21,320 megawatts, and a number of small to medium-size projects on tributaries. A major factor in the cancellation of the dams was the risk of earthquakes along the Nu River fault zone. ==See also==