Second longest source length: Kaidag Qu/Gadag Qu: 48 km ⟶Gyita Qu/Kelao Luo: 56 km ⟶Dulong River: 182 km ⟶N Mai Kha River: 231 km ⟶Irrawaddy River: 2,210 km ⟶Andaman Sea: Total: 2,727 km Longest source length: Quwa Qu/Ridong Ermei ⟶Gyita Qu/Kelao Luo: 56 km ⟶...
TheIrrawaddy River (Burmese:ဧရာဝတီမြစ်,pronounced[ʔèjàwədìmjɪʔ],official romanisation:Ayeyarwady[5][note 1]) is the principal river ofMyanmar, running through the centre of the country. Myanmar's most important commercial waterway, it is about 1,350 miles (2,170 km) long. Originating from the confluence of theN'mai andMali rivers,[7] it flows from north to south before emptying through theIrrawaddy Delta in theAyeyarwady Region into theAndaman Sea. Itsdrainage basin of about 404,000 square kilometres (156,000 sq mi) covers 61% of the land area ofBurma, and contains five of its largest cities.[8]
As early as the sixth century, the river was used for trade and transport, and an extensive network ofirrigation canals was developed to support agriculture. The river is still of great importance as the largest commercial waterway of Myanmar.[9] It also provides importantecosystem services to different communities and economic sectors, including agriculture, fisheries, and tourism.[8]
In 2007,Myanmar's military dictatorship signed an agreement for the construction of sevenhydroelectric dams, yielding a total of 13,360 MW, on the N'mai and Mali Rivers, including the 3600 MWMyitsone Dam at theconfluence of both rivers. Environmental organisations have raised concerns about the project's ecological impact on the river's biodiverseecosystems. Animals potentially impacted include the endangeredIrrawaddy dolphin and the critically endangeredGanges shark.
The name "Irrawaddy" is derived fromPali.Irāvatī[10] orAirāvatī (Erāvatī in Pali) is the name of theelephant mount ofSakka andIndra in Hinduism. Saka is an importantdeva in Buddhism and elephants were often a symbol for water[11] and were used as the name for several other rivers, such as theAchiravati. It can also be based onIravati, who birthed the mythological elephant. The Irrawaddy gives its name to the Irrawaddy dolphin (Orcaella brevirostris), which is found in the lower reaches of the river and known to help fishers who practice cast-netfishing. Though called the Irrawaddy dolphin, it has been also found in theBay of Bengal and theIndian Ocean.[12][13]
The Irrawaddy River arises by theconfluence of the N'mai (Nam Gio) and Mali Rivers inKachin State. Both the N'mai and Mali Rivers find their sources in the Himalayanglaciers ofUpper Myanmar near 28° N. The eastern branch of the two, the N'mai,[15] is the largest and rises in the Languela Glacier north ofPutao.[16] It is unnavigable because of the strong current whereas the smaller western branch, the Mali River, is navigable, despite a fewrapids. Therefore, the Mali River is still called by the same name as the main river by locals.[17] The controversialMyitsone Dam is no longer under construction at the convergence of these rivers.
The town ofBhamo, about 240 kilometres (150 mi) south of the Mali and N'mai river confluence, is the northernmost city reachable by boat all year round although during themonsoons most of the river cannot be used by boats. The city ofMyitkyina lies 50 kilometres (31 mi) south of the confluence and can be reached during the dry season.
Between Myitkyina andMandalay, the Irrawaddy flows through three well-markeddefiles:[18]
About 65 kilometres (40 mi) downstream from Myitkyinā is the first defile.
Below Bhamo the river makes a sharp westward swing, leaving the Bhamo alluvial basin to cut through thelimestone rocks of the second defile. This defile is about 90 metres (300 ft) wide at its narrowest and is flanked by vertical cliffs about 60 to 90 metres (200–300 ft) high.
About 100 kilometres (62 mi) north of Mandalay, atMogok, the river enters the third defile. BetweenKatha and Mandalay, the course of the river is remarkably straight, flowing almost due south, except near Kabwet,[19] where a sheet oflava has caused the river to bend sharply westward.
This sheet of lava is theSingu Plateau, a volcanic field from theHolocene. This field consists ofmagma from the fissure vents and covers an area of about 62 square kilometres (24 sq mi). The plateau is also known as Letha Taung.[20]
Leaving this plateau atKyaukmyaung,[21] the river follows a broad, open course through the centralDry Zone[22] – the Bamar people's ancient cultural heartland[23] – where large areas consist ofalluvial flats. From Mandalay (the former capital of the kingdom of Myanmar), the river makes an abrupt westward turn before curving southwest to unite with theChindwin River, after which it continues in a southwestern direction. It is probable that the upper Irrawaddy originally flowed south from Mandalay, discharging its water through the presentSittaung River to theGulf of Martaban, and that its present westward course is geologically recent. Below its confluence with the Chindwin, the Irrawaddy continues to meander through the petroleum producing city ofYenangyaung, below which it flows generally southward. In its lower course, betweenMinbu andPyay, it flows through a narrow valley between forest-covered mountain ranges—the ridge of theArakan Mountains[24][25] to the west and that of thePegu Yoma Mountains to the east.[26][27]
The delta of the Irrawaddy begins about 93 kilometres (58 mi) aboveHinthada (Henzada) and about 290 kilometres (180 mi) from its curved base, which faces the Andaman Sea. The westernmost distributary of the delta is thePathein (Bassein) River, while the easternmost stream is the Yangon River, on the left bank of which stands Myanmar's former capital city, Yangon (Rangoon). Because theYangon River[28] is only a minor channel, the flow of water is insufficient to preventYangon Harbour from silting up, and dredging is necessary. The relief of the delta's landscape is low but not flat.[29] The soils consist of fine silt, which is replenished continuously by fertilealluvium carried downstream by the river. As a result of heavy rainfall varying from 2,000 to 3,000 millimetres (79–118 in) a year in the delta,[30] and the motion and sediment load of the river,[31] the delta surface extends into the Andaman Sea at a rate of about 50 metres (160 ft) per year.[32]
Due tomonsoonal rains, which occur between mid-May and mid-October, the volume of the Irrawaddy and itstributaries varies greatly throughout the year. In summer, the melting of the snow[33] andglaciers in Northern Burma add to the volume. The averagedischarge near the head of the delta is between a high of 32,600 cubic metres (1,150,000 cu ft) and a low of 2,300 cubic metres (81,000 cu ft) per second. The discharge can be as high as 40,393 cubic meter per second in the rainy season.[34] Over a year, the discharge averages 15,112 cubic metres (533,700 cu ft). Further North, atSagaing, the[1] shows a 38% decrease in discharge compared to where the river enters the delta.[35] it also silted up around 278 tons of sand every year.
Variation between high and low water levels is also great.[36] AtMandalay andProme, a range of 9.66 to 11.37 metres (31.7–37.3 ft) has been measured between low-water level and flood level respectively. Because of the monsoonal character of the rain, the highest point is recorded in August, the lowest in February.
This variation in water level makes it necessary for ports along the river to have separate landing ports for low- and high-water.[36] Still, low water levels have caused problems for ports along the river, as in theBamaw–Mandalay–Pyay sectors, the shallowest point is as shallow as 60 centimetres (2.0 ft).[37]
Within thebasin, the average population density is 79 people/km2. For these people, the river supply amounts to 18,614 m3 per person per year.[38]
Collectively, the modern Ayeyarwady (Irrawaddy) and Thanlwin (Salween) rivers deliver >600 Mt/yr of sediment to the sea.[39] Most recent study shows: 1) There is little modern sediment accumulating on the shelf immediately off the Ayeyarwady River mouths. In contrast, a major mud wedge with a distal depocenter, up to 60 m in thickness, has been deposited seaward in the Gulf of Martaban, extending to ~130 m water depth into the Martaban Depression. Further, 2) There is no evidence showing that modern sediment has accumulated or is transported into the Martaban Canyon; 3) There is a mud drape/blanket wrapping around the narrow western Myanmar Shelf in the eastern Bay of Bengal. The thickness of the mud deposit is up to 20 m nearshore and gradually thins to the slope at −300 m water depth, and likely escapes into the deep Andaman Trench; 4) The estimated total amount of Holocene sediments deposited offshore is 1.290 trillion tons. If we assume this has mainly accumulated since the middle Holocene highstand (~6000 yr BP) like other major deltas, the historical annual mean depositional flux on the shelf would be 215 Mt/yr, which is equivalent to ~35% of the modern Ayeyarwady-Thanlwin rivers derived sediments; 5) Unlike other large river systems in Asia, such as the Yangtze and Mekong, this study indicates a bi-directional transport and depositional pattern controlled by the local currents that are influenced by tides, and seasonally varying monsoons winds and waves.[39]
Thespot-billed pelican was once widespread in Asia, but is not known to breed in Myanmar anymore.Although thesaltwater crocodile is not common in Myanmar, they do live in and near reserved forests. Attacks on people[40] still occur in the Irrawaddy river.
No complete and precise list of all the fish in the Irrawaddy river basin currently exists, but in 1996 it was estimated that there are about 200 species.[41] In 2008, it was estimated that the Irrawaddyecoregion is home to 119–195 species of fish found nowhere else in the world (endemic).[41] Severalnew species of fish have been described from the Irrawaddy river basin in recent years (for example, thecyprinidDanio htamanthinus in 2016 and thestone loachMalihkaia aligera in 2017), and it is likely thatundescribed species remain.[42][43]
Among the most well-known species in the river is theIrrawaddy dolphin (Orcaella brevirostris), aeuryhaline species of oceanic dolphin with a high and rounded forehead, lacking a beak. It is found in discontinuous sub-populations near sea coasts and in estuaries and rivers in parts of theBay of Bengal and South-East Asia.
Along the north–south course of the Irrawaddy River, a number of notably different ecoregions can be distinguished.
The streams of the Nmai and Mali that form the Irrawaddy originate in high and remote mountains near the border withTibet. This part of Myanmar, which extends north fromMyitkyina and the Irrawaddy confluence, lies entirely outside the tropics. Rain falls at all seasons of the year, but mostly in the summer. The valleys and lower hill ranges are covered with tropical andsubtropical evergreenrainforest instead of monsoon (deciduous) forest. This region is characterised by subtropical andtemperate forests ofoak andpine are found at elevations above 900 metres (3,000 ft). This evergreen forest passes into sub-tropical pine forest at about 1,500 metres (4,900 ft) feet. Above 1,800 metres (5,900 ft), are forests ofrhododendrons, and that in turn into evergreenconifer forest above 2,400 metres (7,900 ft) feet.
The Irrawaddy river basin covers an approximate area of 255 81 km2 (31 sq mi).[44] The Central Basin consists of the valley of the middle Irrawaddy and lower Chindwin. It lies within the 'dry zone' and consists almost entirely of plains covered with theteak-dominatedIrrawaddy moist deciduous forestsecoregion, which surrounds dry forest patches in drier areas. The central basin receives little rain (ave 650mm per year) although it does flood quickly during the July–October storms. The one meteorological factor which does not vary greatly, and which is the most important for plant life, is atmospherichumidity. This is always high, except in the winter in certain localities. Humidity usually does not fall below 75% and is 90% or more for long periods during the summer. Another feature is the prevalent southerly summer winds which erode the soil of the basin.
The natural habitats of this central zone have been much altered for farming and there are few protected areas.
The predominant trees of the drier patches are the thornyTerminalia oliveri and the hardwood dahatteak (Tectona hamiltoniana) with stands of Indaing (Dipterocarpus tuberculatus) which is cut for timber. The wildlife includes many birds, small mammals and reptiles such as the hugeBurmese python. However, most of the large animals including the tiger have been hunted out or seen their habitats disappear.
The Irrawaddy River and itstributaries flow into the Andaman Sea through the Irrawaddy Delta. Thisecoregion consists ofmangroves and freshwaterswamp forests. It is an extremely fertile area because of the river-bornesilt deposited in the delta. The upper and central portions of the delta are almost entirely undercultivation, principally for rice. The southern portion of the ecoregion transitions into theBurmese Coast mangroves[45] and is made up of fanlikemarshes withoxbow lakes, islands, and meanderingstreams.[46][47]
Birds of the delta are both winter visitors and passage migrants includinggreat cormorant (Phalacrocorax carbo), a wide variety ofAnatidae,Eurasian coot (Fulica atra), about thirty species ofmigratory shorebirds, thewhiskered tern (Chlidonias hybrida), theCaspian tern (Hydroprogne caspia), and thebrown-headed gull (Larus brunnicephalus), which is very common. One of the most numerous wintering shorebird is thelesser sand plover (Charadrius mongolus), which occurs in flocks of many thousands along the outer coast of the delta. Thewood sandpiper (Tringa glareola) andred junglefowl (Gallus gallus) are also abundant.
In the late 19th century, thespot-billed pelican (Pelecanus philippensis) nested in huge numbers in south Myanmar. One colony on theSittaung River plain to the east of the delta was described in November 1877 as covering 300 square kilometres (100 sq mi) and containing millions of birds. Immense colonies still bred in the area in 1910, but the birds had disappeared completely by 1939. Small numbers were regularly reported in the delta in the 1940s, but no breeding sites were located. As of 2010[update], no pelicans have been recorded, and it may well be that the species is now extinct in Myanmar.[48]
Several species of largemammal occur in the delta, but their populations are small and scattered, with the possible exceptions of theMalayan sambar deer (Cervus unicolor equinus),Indian hog deer (C. porcinus), andwild boar (Sus scrofa), which have been reported from all Reserved Forests.Asian elephants (Elephas maximus) were once widespread throughout the country with numbers as high as 10,000 animals, but in the last decade[update] numbers have dwindled, partly due to transferring the animals to logging camps.[49] Other species reported to be present include theleopard,Bengal tiger,crab-eating macaque,wild dog, andotters (Panthera pardus, P. tigris, Cuon alpinus, andLutra species).[50]
Thesaltwater crocodile (Crocodylus porosus) can be found in the southern part of the delta. The species was formerly abundant in coastal regions, but population numbers have decreased because of a combination of commercial skin hunting, habitat loss, drowning in fishing nets and over-collection of living animals to supplycrocodile farms.[51]
It was at this river that a battle between a saltwater crocodile and a tiger was observed that ended with the reptile devouring the tiger.[52]
The Irrawaddy River has five major tributaries. As they flow through the northern tip of Myanmar – theKachin State – they cut long north–southalluvial plains and relatively narrow uplandvalleys between the 2,000 to 3,000 metres (7,000–10,000 ft) mountain ridges.[54] The rivers joining the Irrawaddy are, from north to south:
Towards the mouth, the river also has severaldistributaries such as thePathein River, the westernmost distributary serving the inland port city ofPathein.[55]
Pullingteak logs, made into largerafts and floated down the Irrawaddy River, ashore nearMandalay.Market activity in the Irrawaddy
As early as the sixth century, theBamars were using the Irrawaddy to gain power in the region through trade and transport on the China –India route. By the twelfth century, a well-developed network ofcanals made for flourishing rice cultivation. Later, the river became a key economic tool ofImperial British interests, who set up trading ports along its shores.[56]
Today, the Irrawaddy is still the country's most important commercial waterway. Despite Mandalay's position as the chief rail and highway focus in northern Myanmar, a considerable amount of passenger and goods traffic moves by river. As the Irrawaddy Delta is one of the world's major rice-growing areas, one of the most important goods transported is rice.Teak logs – Myanmar is one of the world's top exporters – are floated down the river as large rafts. Before it is transported, teak has to be seasoned, because otherwise it won't float.[57] This happens bygirdling, a practice where a deep circular cut through bark andsapwood is made into the heartwood. Other major goods that are transported from the nation's heartlands toYangon for export are other foodstuffs, petroleum, cotton, and local commodities.
Commercial transportation on the Irrawaddy is maintained for about 1,300 kilometres (810 mi): fromHinthada to Bhamo (1,080 kilometres (670 mi)) throughout the year, but from Bhamo to Myitkyina (200 km) for only seven months. More than 3,200 kilometres (2,000 mi) of navigable waterways exist in the Irrawaddy delta, and there is a system of connecting canals. The Sittang is usable by smaller boats, but theSalween River, because of its rapids, is navigable for less than 160 kilometres (99 mi) from the sea. Small steamers and country boats also serve the coasts of theRakhine State andTanintharyi Region. On theChindwin River, transportation is carried on by steam or diesel vessels throughout the year up toHomalin—about 640 km from its confluence with the Irrawaddy. Seasonal navigation is carried on intoTamanthi, which is 57 miles (92 km) by river above Homalin.
The Chindwin valley has no railroad and relies heavily on river transport.Chauk, downstream from the confluence in the oil-field district, is a petroleum port. It is linked to Yangon by road and rail.Hinthada, near the apex of the delta, is the rail junction for lines leading toKyangin andBassein (Pathein). A ferry operates between Hinthada on the west bank and the railway station atTharrawaddy on the east bank.
Unregulated gold mining during the2021 Myanmar civil war, mostly in the north of the river basin, has led to high levels of contamination across the river's run with high levels ofmercury,cadmium andmagnesium in samples taken from Pathein to Kachin State. The environmental and health concerns are highest in the north, where locals were reported to have suffered from skin conditions from using the contaminated water and fish are no longer regarded as safe to consume.[58]
Myanmar'smilitary junta signed an agreement withChina Power Investment Corporation in May 2007 for the construction of sevenhydroelectric dams along the Irrawaddy,Mali, andN'Mai rivers in Kachin State. The total planned output of all seven plants will be 15,160 MWs of electricity, making it the largest hydropower project in Myanmar, surpassing the 7100 MWTasang Dam in Shan State.[59]The following data is available for the dam locations:
Capacity, Height and Length Data for the Dam Projects
Location
Myitsone
Chibwe
Pashe
Lakin
Phizaw
Khaunglanphu
Laiza
Height (m)
152
47.5
–
–
–
–
–
Length (m)
152
220
–
–
–
–
–
Capacity (MW)
3,600
2,800
1,600
1,400
1,500
2,700
1,560
The power generated by the dams will be transmitted to other countries in the South-East Asian region, with most going to China.[60] Other countries targeted for power export areThailand, India andBangladesh.
The largest of the seven, theMyitsone Dam, is located at the confluence of the Mali and N'Mai Rivers at the creation of the Irrawaddy. Although theChina Power Investment Corporation is project manager of the Confluence Region Hydropower Projects.[61] ParConfluence Region Hydropower Projects, several companies have been or are currently involved in the preparation, construction and financing of the 3,600 MW Myitsone Dam.[62]Asia World Company has a key position, amidst Burmese Suntac Technologies[63] and state-run Myanmar Electrical Power Enterprise, a state-owned utility enterprise responsible for power generation, transmission and distribution[64]
Due to its location and size, construction of the Myitsone Dam has raised significant ecological andsociological concerns. According to the Irrawaddy Myitsone Dam Multipurpose Water Utilizing Project study, the maximum water level of the reservoir will be 290 metres. This makes for a flood zone of 766 km2, compromising 47 villages.[68]
Other consequences of the inundation include loss of farmland, loss of spawning habitat as fish can not swim upstream anymore. The Kachin Development Networking Group,[69] a network of civil society groups and development organisations inKachin State warn this will lead to a loss of income for fishermen. They report locals are also worried about the flooding of cultural sites in the flood zone. As with other large dam projects, the Myitsone Dam construction will alter thehydrological characteristics of the river, e.g. preventingsediment from enriching riverbanks downstream, where it usually enriches the riverside food-producing plains.[70] This can affect fertility as far downstream as theIrrawaddy Delta, the major rice-producing area of Myanmar.
Ecological concerns focus on theinundation of an area that is the border of the Indo-Burma and South Central Chinabiodiversity hotspots. The Mali and N'mai River confluence region falls within the Mizoram-Manipur-Kachinrainforests, added to theWWF list of outstanding examples of biodiverse regions.[71]
The location of the Myitsone Dam, located less than 100 km from afault line where theEurasian andIndian tectonic plates meet, raised concerns about its earthquake resistance. Earthquakes in the region, such as the 5.3magnitude earthquake that struck near the Myanmar-China border on 20 August 2008,[72] prompted Naw Lar, the coordinator of the KDNG dam research project, to ask the junta to reconsider its dam projects.[73]
TheAva Bridge nearSagaing, rebuilt in 1954 after the wartime destruction of the original bridge built in 1934, was the only bridge over the Irrawaddy until 1998. The bridge collapsed during the 2025 earthquake.TheIrrawaddy Bridge (Yadanabon)
Until the construction of theAva (Innwa) Bridge, a 16 span rail and roadcantilever bridge built by the British colonial government in 1934, the only way across the Irrawaddy was by ferry. The bridge was destroyed by the retreating British Army duringWorld War II and was rebuilt in 1954 after Burmese independence and was the only bridge to span the Irrawaddy until recent times when a spate of bridge construction has been carried out by the government.[74][75]
^abFei, Yu (22 August 2011)."中国科学家确定雅鲁藏布江等四条国际河流源头" [Chinese Scientists Verify Source of Four International Rivers, Including Yarlung Tsangpo].Xinhua News Agency (in Chinese). Retrieved5 March 2021.
^"Water Resources of Myanmar". AQUASTAT. Archived fromthe original on 27 July 2010. Retrieved21 September 2010.Adding the sections gives Irrawaddy a discharge of 476.9 cubic kilometers per year, which translates to 15,112 m3/s
^Khon Ra (21 September 2011)."Water Quality Management at River Basin in Myanmar"(PDF).Water Environment Partnership in Asia (WEPA). The Republic of the Union of Myanmar Ministry of Agriculture and Irrigation. p. 2. Archived fromthe original(PDF) on 16 August 2016. Retrieved26 March 2017.Catchment Area (000's sq-km) Chindwin River 115.30 Upper Ayeyarwady River 193.30 Lower Ayeyarwady River 95.60
^"MSN".NBC News. 20 April 2008. Retrieved18 August 2010.
^abAllen, D.J.; S. Molur; B.A. Daniel, eds. (2010).The Status and Distribution of Freshwater Biodiversity in the Eastern Himalaya. IUCN. pp. 22–23.ISBN978-2-8317-1324-3.
^Kottelat, M. (2017). "A new genus and three new species of nemacheilid loaches from northern Irrawaddy drainage, Myanmar (Teleostei: Cypriniformes)".Raffles Bulletin of Zoology.65:80–99.
^Tin Maung Maung Than. (2005).Myanmar's Energy Sector: Banking on Natural Gas Myanmar's Energy Sector: Banking on Natural Gas In Chin Kin Wah & Daljit Singh (Eds.), Southeast Asian Affairs 2005 (pp. 257–289). Singapore: Institute of Southeast Asian Studies.
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