Irrawaddy Delta

The Irrawaddy Delta or Ayeyarwady Delta lies in the Irrawaddy Division, the lowest expanse of land in Myanmar that fans out from the limit of tidal influence at Myan Aung to the Bay of Bengal and Andaman Sea, 290 kilometres (180 mi) to the south at the mouth of the Ayeyarwady River. The delta region is densely populated, and plays a dominant role in rice cultivation in its rich alluvial soil as low as just 3 metres (9.8 ft) above sea level. It also includes fishing communities in a vast area full of rivers and streams.

The Irrawaddy Delta comprises the main arms of Pathein River, Pyapon River, Bogale River, and Toe River. Mawtin Point, formerly Cape Negrais, is a famous landmark in the Irrawaddy Division, and it also marks the south west end of Myanmar. The delta begins around 93 km above Hinthada.

The highest point of the delta, Waphu Mount (404 m (1,325 ft)) lies between Pathein and Mawtin Zun (point), on the western strip of the delta. A major portion of the area is covered with low-lying lands just 3 metres (9.8 ft) above sea level. This alluvial plain is bounded to the west by the Rakhine Yoma and to the east by the Bago Yoma. It is dissected into peninsulas and islands by the large southward flowing rivers which are subject to tidal intrusion. The lower seaward third of the delta is completely flat with no local relief and stretches for 130 kilometres (81 mi) from east to west.

The waters of these rivers are very turbid due to a heavy silt load they carry and the sea is very shallow with depths less than 5.5 metres (18 ft) across the coastline and in the east for a distance of up to 28 kilometres (17 mi) offshore. As a result of constant accretion into the sea, the delta is advancing at a rate of 5–6 kilometres (3.1–3.7 mi) per 100 years, equivalent to about 1,000 hectares per year.

Annual rainfall in the delta region is approximately 2,500 mm (98.4 in), with a mean temperatures of 32 °C (90 °F). Most of the rain falls during the monsoons between mid-May and mid-November. It is cool and dry from mid-October to mid-February when temperatures begin to rise with premonsoon squalls in April and early May.

Water purity lies within the pH range of alkaline condition due to early natural resources and weak environmental control. Mangroves or lamu and nipa palm or dani are the major vegetation of the delta. Moreover, control of weeds is less active as local farmers make mats during the summer. Destruction of mangroves and deforestation in the coastal region due to the Cyclone Nargis put it more at risk in future.

The principal islands include Haingyi Kyun, Leit Kyun (Turtle Island), Pyin Salu Kyun, and Meinmahla Kyun (Pretty Women Island).

Major cities include Bogale, Maubin, Myaungmya, Moulmeingyun, Pantanaw, Pathein, Pyapon, Dedaye up to Twante, Kyauktan, and Hinthada Township