1.1. Hazards
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.