The Irrawaddy River or Ayeyarwady River(,) is a river that flows from north to south of Burma (Myanmar). It is the country's largest river and most important commercial waterway. Originating from the confluence of the N'mai and Mali rivers, it flows relatively straight North-South before emptying via the Irrawaddy Delta in the Andaman Sea. Its drainage area of about 413,000 km² covers a large part of Burma. After Rudyard Kipling's poem, it is sometimes referred to as 'The Road to Mandalay'.

As early as the sixth century the river was used for trade and transport. Having developed an extensive network of irrigation canals, the river became important to the British Empire after it had colonized Burma. The river is still as vital today, as a considerable amount of (export)goods and traffic moves by river. Rice is produced in the Irrawaddy Delta, irrigated by water from the river. Another important export good, Teak, is floated down the river to Yangon.

In 2007, Burma's military government signed an agreement for the construction of seven dams, yielding a total 13,360 kW, in the N'mai and Mali Rivers, including the 3,600 kW Myitsone Dam at the confluence of both rivers. Environmental organisations have raised concerns about the ecological impacts on the river's biodiverse ecosystems. Animals potentially impacted include the threatened Irrawaddy Dolphin.

Etymology

The Burmese name of Irrawaddy (transliterated by the government of Burma as Ayeyarwady) is derived from the ancient name of the river Ravi, Airavati, in the Punjab region, but through its Pali, rather than its Sanskrit form.. Airavati in turn is the name of the elephant mount of Indra, a minor Indian god. Elephants were in Indian mythology often a symbol for water

When transliterated literally from Burmese spelling, the modern rivername comes down to Erawati. Due to the spreading of Buddhism in South-East Asia, some names in Burma, and to a lesser extent in other South-East Asian countries, are adaptations of Indian place names associated with Buddhism, e.g. Myawaddy (originated from Amaravati), Dvaravati, Ayuthia (originated from Ayoddhya or Ayujjha), Cambodia (originated from Kamboja). Erawati also belongs to this category, as it is also the ancient name of the river Ravi in Punjab". The ancient name was Airavati, in Sanskrit meaning:

• ira -any drinkable fluid; a draught (especially of milk),...food, refreshment, ..vat...granting drink or refreshment,...name of a river in Panjab now called Ravi..

• Airavata (fr.ira-vat), a descendant of Ira-vat;....,N. of Indra’s elephant...(i) the female of Indra’s elephant; N. of a river,...;lightning...."

This is incompatible with Erawati, as it does not start with the vowel e. When the ancient name of the Ravi is rendered in Romanised Pali though, it is Eravati, which is compatible with the modern transliteration of the rivername, Erawati. The above means that not influence by Arabic (via Wadi), or Sanskrit (via Airavati) but Pali (via Eravati) has determined the name of the Irrawaddy.

The Irrawaddy gives its name to a dolphin, the Irrawaddy dolphin (Orcaella brevirostris), which is found in the upper reaches of the river and known to help fishermen who practice cast-net fishing. Though sometimes called the Irrawaddy River Dolphin, it is not a true river dolphin, since it is also found at sea.

Physiography

The Irrawaddy River bisects Burma from north to south and empties through the nine-armed Irrawaddy Delta into the Indian Ocean.

Source

The Irrawaddy River arises by the confluence of the N'mai and Mali Rivers in Kachin State . Both the N'mai and Mali Rivers find their sources in the Himalaya glaciers of Northern Myanmar, in the vicinity of 28° N . The eastern branch of the two, N'mai, river is the larger stream and rises in the Languela Glacier north of Putao. It is unnavigable because of the strong current whereas the smaller western branch, the Mali river, is navigable, despite a few rapids. Herefore, the Mali river is still called by the same name as the main river by locals.

The town of Bhamo, about 150 miles (240 km) south of the Mali and N'mai river confluence, is the northernmost city reachable by boat all the year round although during the monsoons most of the river cannot be used by boats. The city of Myitkyina however lies south of the confluence and can be reached during the dry season.

Defiles

Between Myitkyina and Mandalay, the Irrawaddy flows through three well-marked defiles :

• About 40 miles (65 km) downstream from Myitkyinā is the first defile.

• Below Bhamo the river makes a sharp westward swing, leaving the Bhamo alluvial basin to cut through the limestone rocks of the second defile. This defile is about 300 feet (90 m) wide at its narrowest and is flanked by vertical cliffs about 200 to 300 feet (60 to 90 metres) high.

• About 60 miles (100 km) north of Mandalay, at Mogok, the river enters the third defile. Between Katha and Mandalay, the course of the river is remarkably straight, flowing almost due south, except near Kabwet, where a sheet of lava has caused the river to bend sharply westward.

This sheet of lava is the Singu Plateau, a volcanic field from the Holocene. This field exists of magma from the fissure vents and cover an area of about 62 km². The plateau is also known as Letha Taung.

Leaving this plateau at Kyaukmyaung , the river follows a broad, open course through the central dry zone - the ancient cultural heartland — where large areas consist of alluvium flats. From Mandalay (the former capital of the kingdom of Myanmar), the river makes an abrupt westward turn before curving southwest to unite with the Chindwin 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 present Sittoung River to the Gulf 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 of Yenangyaung, below which it flows generally southward. In its lower course, between Minbu and Prome, it flows through a narrow valley between forest-covered mountain ranges—the ridge of the Rakhine Yoma Mountains to the west and that of the Pegu Yoma Mountains to the east.

The Irrawaddy Delta

The delta of the Irrawaddy begins about 58 miles (93 km) above Hinthada (Henzada) and about 180 miles (290 km) from its curved base, which faces the Andaman Sea. The westernmost distributary of the delta is the Pathein (Bassein) River, while the easternmost stream is the Yangon River, on the left bank of which stands Myanmar’s capital city, Yangon (Rangoon). Because the Yangon River is only a minor channel, the flow of water is insufficient to prevent Yangon Harbour from silting up, and dredging is necessary. The relief of the delta’s landscape is low but not flat. The soils consist of fine silt, which is replenished continuously by fertile alluvium carried downstream by the river. As a result of heavy rainfall varying from 80 to a year in the delta, and the motion and sediment load of the river, the delta surface extends into the Andaman Sea at a rate of about 165 feet (50 m) per year.

Hydrography

Due to monsoonal rains, which occur between mid-May and mid-October, the volume of the Irrawaddy and its tributaries varies greatly throughout the year. In summer, the melting of the snow and glaciers in Northern Burma add to the volume. The average discharge near the head of the delta is between a high of 32,600 cubic metres (1,152,000 cubic feet) and a low of 2,300 cubic metres (82,000 cubic feet) per second. Over a year, the discharge averages 13,000 cubic metres (460,000 cubic feet). Further North, at Sagaing, the shows a 38% decrease in discharge compared to where the river enters the delta.

Variation between high and low waterlevel is also great. At Mandalay and Prome, a range of 9,66 metre (31,7 feet) and 11,37 metre (37,3 feet) respectively has been measured between low-water level and floodlevel. 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. Still, low water levels have caused problems for ports along the river, as in the Bamaw–Mandalay–Pyay sectors, the shallowest point is as shallow as 2 feet.

Within the basin, the average population density is 79 people/km². For these people, the river supply amounts to 18,614 m³ per person per year.

Flora

Along the North-South course of the Irrawaddy River, three regions with notably different flora can be distinguished.

• Northern Mountains

• The Central Basin and Lowlands

• Irrawaddy Delta Area

Northern Mountains

The streams of the Nmai and Mali that form the Irrawaddy originate in high and remote mountains near the border with Tibet. This part of Burma, which extends north from Myitkyina and the Irrawaddy confluence, lies entirely outside the tropics. Rain falls at all seasons of thy year, but mostly in the summer. The valleys and lower hill ranges are covered with tropical and subtropical evergreen rainforest instead of monsoon (deciduous) forest. This region is characterised by subtropical and temperate forests of oak and pine are found at elevations above 3,000 feet (900 metres). This evergreen forest passes into sub-tropical pine forest at about 5000 feet Above 6,000 feet (1,800 metres), are forests of rhododendrons, and that in turn into evergreen conifer forest above 8000 feet.

The Central Basin and Lowlands

The Central Basin consists of the valley of the middle Irrawaddy and lower Chindwin. It lies within the 'dry zone' and consists almost enterirely of plains covered with thorn forest and tropical dry and moist deciduous forest, which comprise the teak-dominated moist deciduous forests and the drier patches of Dipterocarpus-dominated dry deciduous forests, respectively. The one meteorological factor, and that is the most important for plant life, which does not greatly vary is atmospheric humidity. This is always high, except locally, in the winter. It usually does not fall below 75% and is 90% or more for long periods during summer.

Irrawaddy Delta Area

The Irrawaddy River and it's tributaries flow into the Andaman Sea through the Irrawaddy Delta. This ecoregion consists of mangroves and freshwater swamp forests. It is an extremely fertile area because of the riverborne silt deposited in the delta. The upper and central portions of the delta are almost entirely under cultivation, principally for rice. The southern portion of the ecoregion transitions into the Myanmar Coastal Mangroves and is made up of fanlike marshes with oxbow lakes, islands, and meandering rivulets and streams.

Fauna

The Irrawaddy river is home to a large diversity of animals, including about 43 fishspecies.

The most well-known of these species is the Irrawaddy Dolphin (Orcaella brevirostris), a euryhaline 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 the Bay of Bengal and South-East Asia.

As for birds, winter visitors and passage migrants include Phalacrocorax carbo, a wide variety of Anatidae, Fulica atra, about 30 species of migratory shorebirds, Chlidonias hybrida, Hydroprogne caspia and the Brown-headed Gull (Larus brunnicephalus), which is very common. One of the most numerous wintering shorebird is the Lesser Sand Plover (Charadrius mongolus), which occurs in flocks of many thousands along the outer coast of the delta. The Wood Sandpiper and Red Junglefowl (Tringa glareola) are also abundant.

In the late 19th century, the Spot-billed Pelican (Pelecanus philippensis) nested in huge numbers in south Burma. One colony on the Sittang plain to the east of the delta was described in November 1877 as covering 100 square miles 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. No pelicans have been recorded in recent years, and it may well be that the species is now extinct in Burma.

Several species of large mammal occur in the delta, but their populations are small and scattered, with the possible exceptions of the Malayan Sambar (Cervus unicolor equinus), Hog Deer (C. porcinus) and Wild 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 de last decade numbers have dwindled, partly due to transferring the animals to logging camps. Other species reported to be present include the Leopard,Bengal Tiger, Crab-eating macaque, Wild Dog and otters (Panthera pardus, P. tigris, Cuon alpinus and Lutraspecies).

The estuarine crocodile (Crocodylus porosus) can be found in the Southern part of the river delta. The species was formerly abundant in coastal regions of Burma, but is now known principally from the lower Ayeyarwady Delta. 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 supply crocodile farms.

Despite recent declines in the Sea Turtle populations, five species are known to nest in Burma at well known island and mainland beaches known as turtle-banks. These are the Olive Ridley (Lepidochelys olivacea), loggerhead(Caretta caretta), green (Chelonia mydas), hawksbill (Eretmochelys imbricata), andleatherback(Dermochelys coriacea) marine turtles.

Tributaries

The Irrawaddy River has five major tributaries. As they flow through the northern tip of Burma — the Kachin State — they cut long north-south alluvial plains and relatively narrow upland valleys between the 7,000 to 10,000 ft mountain ridges. The rivers joining the Irrawaddy are, from north to south:

• Taping River

• Shweli River

• Myitnge River

• Mu River

• Chindwin River

Economy and Politics

The river flows through the following cities:

• Putao

• Myitkyina

• Bhamo

• Katha

• Tagaung

• Kyaukmyaung

• Mandalay

• Sagaing

• Chauk

• Bagan

• Nyaung-U

• Magway

• Pyay

• Hinthada

• Pantanaw

Bridges

Until the construction of the Ava (Innwa) Bridge, a 16 span rail and road cantilever 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 during the World 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.

• Ayeyarwady Bridge (Yadanabon) just upstream from the old Ava Bridge at Sagaing

• Bala Min Htin Bridge over the N'Mai Hka at Myitkyina, November 1998

• Anawrahta Bridge at Chauk, April 2001

• Ayeyarwady-Magway Bridge at Magway

• Bo Myat Tun Bridge at Nyaungdon, November 1999

• Nawaday Bridge at Pyay, September 1997

• Maubin Bridge at Maubin, February 1998

• Ayeyarwady-Dedaye Bridge at Dedaye

Gallery