|Natural Disasters in South East Asia and Bangladesh - Vulnerability Risks and Consequences (Centre for Research on the Epidemiology of Disasters - International Center for Training Exchanges in the Geosciences, 1998, 83 p.)|
|PART IV - SYNOPTIC ASSESSMENT OF NATURAL HAZARDS ON A NATIONAL SCALE|
|1. Criteria used to identify territories prone to risks|
Other than volcanism (the Philippines) and the effects due to earthquakes (the Philippines, Bangladesh, Myanmar and Vietnam) there are 8 hazards (see key for the maps of the territories prone to risks). As mentioned above, floods and cyclones are the most dominant. Floods are subdivided into river floods, which have an annual frequency because of the effects of the monsoon winds, and flash floods of the mountain rivers
Cyclones affect preferably coasts, deltas, coastal plains but also the mountains exposed to winds such as the Annamitic mountain chain in Vietnam, the Arakan Yoma mountains in Bangladesh and Myanmar which will be called coastal mountains.
Floods related to great rivers affect deltas and inland basins. The latter often protected from high intensity cyclones by coastal mountains are not sheltered from droughts because they are practically exposed to wind (Mekong Laotian plains, Menam Chao Phraya and Irraouadi middle basins). The same is true for inland mountains which are preferentially affected by mud slides, landslides and flash floods.
Storm surges and high tides may increase the effects of the annual floods or the floods associated with cyclones in coastal plains and deltas to which one can add the subsidence of deltas. For example the meteorological department in Thailand reported that in 1996 "continuing floods due to high tides remained in several locations of the lower central" (terminal part of the Chao Phraya delta) "especially along the Chao Phraya River banks until November" (13).
13 In: Damage caused by floods, drought, tropical cyclones and other severe weather events in Asia and the Pacific during 1996. Water Res. Journ., June 1997, p. 3
In drawing up an assessment (cf. key to maps of territories prone to risks) it has been possible to identify five national sub-types areas associating, though unequally, the different types of dangers. It is also possible to regroup deltas and coastal plains on one side, and both inland and coastal mountains on the other, the inland basins being notably different from the two preceding groups.
The interest of this approach lies in the fact that the national sub-types groupings correspond to human groups that are also differentiated, and therefore enables the identification of the different types of territories prone to risks.