Part IV - Synoptic assessment of natural hazards on a national scale

The fourth part of the report considers that the global approach of risks is insufficient in as much as the diversities in each country are not taken into consideration. A synoptic assessment of the risks, on a national scale, was therefore carried out. It enabled the identification of a number of territories prone to risks. It was necessary to identify them because of differences in their physical (hazards) and human (occupation and land use, sociopolitical variations) characteristics in the perspective of actions adapted to prevention and preparedness.

With regard to the physical and human criteria, five types of territories prone to risks have been determined. These five types are present either partially or wholly in each of the countries.

* The deltas

The deltas are characterised by a physical environment which increases the danger by the conjunction of cyclones, river floods, high tides, storm surges if not local tsunamis. The deltas because of the rice-growing potential or the presence of major cities that rapidly increase their infrastructure and activities, often have very high population densities. International openings tend to increase the vulnerability by shattering, among others, the earlier traditional measures of risk management. On the other hand, the dominating ethnic groups are in the majority. This factor may, to a certain extent, reduce the vulnerability.

* The coastal plains

The coastal plains are in nature quite similar to the deltas. They are both subject to the same intensities of the destructive phenomena. There is little access, often difficult, to the coastal plains. Except in Bangladesh and with local exceptions, the population density is, on the whole, much lower than in the delta areas. In the same way, the international investments are restricted, selective and vary from one country to another. With the exception of Vietnam, the minority ethnic groups represent a high percentage of the population.

* The inland basins

The inland basins are mainly affected by river floods and droughts. Like in the case of deltas, high population densities are associated with such areas as a result of the presence of historical or present capital cities (in the case of Laos) and an irrigated rice growing activity. The major ethnic group of the countries largely dominates but the international openings are more restricted here than in the deltas. They however vary according to the country. This type of territory is still largely dominated by rural agricultural activity; this is probably why the perception of flood risks is weakened, when droughts are mentally dreaded.

* The coastal mountains

The coastal mountains are directly concerned by cyclones, flash floods and mass movements. These mountains are still associated with the minority ethnic groups who often practice the slash-and-burn cultivation. The access to these mountains remains difficult even though the coastal proximities have sometimes given rise to commercial cultivation. The frequent opposition of the minority groups to the central authorities is also an important vulnerability factor.

* The inland mountains

These mountains are safe from the very strong cyclones. They, however, may experience droughts and are sensitive to flash floods and mass movements. The mountains are occupied by great numbers of the minority ethnic groups who are poorly controlled by the central authorities. The population density is limited and the mountains are far from being easily accessible. There are some very punctual projects in the area that will open the area especially towards China. This will, however, depend on the development of international relations which are considered to be strained in the area.

It is difficult to establish a hierarchy in terms of risks of the 5 territories. Each of the territories has specific types of natural hazards and particular forms of vulnerability even though it is easy to regroup the deltas and coastal plains on one side, and the coastal mountains and inland mountains on the other, and distinguish the inland basins. Therefore a typological classification of zones prone to risks is proposed here more than an attempt of hierarchical organisation based on risk levels. This approach aims at giving a basis of reflection and decision making for some of the solutions that would reduce the risks that cannot be standardised on a national scale but be adapted to the different types of situations.

This being stated, it might be possible to establish priorities. Taking all the human and physical criteria together, the deltas are logically within the very highest risk zones. For the other territories, the hierarchical organisation depends on the criterion considered. Considering the demographic criteria (population size and densities), the inland basins are of main concern. On the other hand, the risks in the coastal plains appear more significant given the striking diversity and potential intensity of the natural hazards alone. Basing on the sociopolitical factors (among others the minorities groups), it is the coastal or inland mountains that appear to be the areas of high risk because of the vulnerability. From this point of view the reduction of the vulnerability can not be a simple technical task. The determination of the priority sectors prone to risks cannot therefore be based on scientific, physical or human criteria only, but also on political choices and considerations.