DEPARTMENT OF METEOROLOGY AND HYDROLOGY (MYANMAR)

 

(18.10.2017): According to the observations at (18:30)hrs M.S.T today, the low pressure area over the west central Bay of Bengal still persists. It is forecast to further intensify into a depression during next (24)hrs. Weather is cloudy over the Andaman Sea and Bay of Bengal.

Hydrological Disaster

Natural Flood Disasters in Myanmar

1.     Intoduction

Natural and man-made flood disasters present dangers to humans and to their property. They present risks, which can be high especially if they are ignored or proper precautions are not taken. The most common natural disasters that are experienced in Myanmar are tropical cyclone associated with surge, flood and drought.

 

2.     Floods

Flood is an event resulting due to the conditions such as abnormally heavy precipitation, rapid snow melts, coastal storm surges, failure of dams and other control works. It is characterized by quick inception, vigorous growth and evident spread terminating eventually with disastrous impacts. Floods of all kinds cause a considerable loss of human life and great property damage. Floods become disasters mostly when human settlements occupy the flood plain.

The floods in Myanmar, mainly occur during the monsoon months (June to October) .The type of floods occur in Myanmar may be generally classified into two; the wide spread flood and flash flood. The wide spread flood mostly occur along Ayeyarwady, Chindwin, Sittoung and Thanlwin which are major rivers and the flash flood usually occur at the small rivers and stream. The main cause of wide spread flood is heavy rainfall striking at the head water regime for considerable period (1 to 3 days), the flood wave forming at the head water started to move downward and causing flood along the river up to the deltaic area. The flash flood is caused by heavy rainfall fell on the source and the flood wave move downward swiftly. Observation shows that the percentage of occurrence of floods (exceeding danger level) in medium and large rivers of Myanmar are 6% in June, 23% in July, 49% in August, 14% in September and 8% in October. The severe floods had occurred in 2004, 1974,1997,1976,1991,1973,1988 and 1997, and order of the years are arranged with respect to their intensities.

 

3.     Causes of River Floods

Ayeyarwady and Chindwin

  • Intense heavy rain due to pronounced monsoon trough persisting for at least 3 days over Northern Myanmar area
  • Heavy rainfall due to cyclonic storm crossing  Myanmar and Bangladesh coasts during early-monsoon and late-monsoon

Sittaung and Thanlwin

  • Mostly due to rainfall associated with low pressure waves ( the remnants of typhoons and tropical storms of South China Sea) moving from east to west across the country