An estimate of the comprehensive impact of natural disasters

In the statistics of the impacts of disasters on the society, one usually counts the economic loss and the loss of human lives, separately. However, we need to know the comprehensive impact for the decision-making in disaster management. For a decision model, it is necessary to consider the loss of human lives, especially in developing countries where 95% of deaths caused by natural disasters occur, in addition to the economic loss, although natural disasters rarely cause a large number of deaths in industrialized countries. However, the likely loss of human lives has rarely been taken into account in the decision models developed by meteorologists, which is mainly attributable to the difficulty in comprehensive estimating the economic loss and the loss of human lives. It is, to some extent, of more importance for decision-making to save human lives than to reduce the economic loss in a modern society, because the number of human fatalities is more concrete and more widely reported and thereby being more deeply concerned by the public. Therefore, a decision model including no impact of disasters on human lives can hardly be accepted by the public and the society.

Here a concept of "economic man" (EM) is postulated to solve the problem mentioned above. An EM is defined as 40 times GNP per capita in the year when a disaster takes place for a specific country and has following features:

1) He is an artificial man and can be converted from the economic loss due to a disaster. 2) He is assumed to contribute economically to the society for 40 years, each year with a GNP per capita in the year when a disaster takes place. It seems reasonable to assume that he could begin his work at the age of 25 and retire at the age of 65. 3) He is assumed to be a perfect substitute of a dead or missing natural man or woman in estimating the comprehensive loss due to a disaster.

With aforementioned definition, we are able to evaluate the comprehensive loss caused by a disaster reasonably. In addition, it is relatively easy to compare the real impact of natural disasters on the society irrespective of differences of the economic status for different countries and for different years in a specific country.

The comprehensive impact may be calculated as the number of economic men killed plus a times the number of human fatalities. Here parameter a can be determined by conducting a questionnaire survey. a is the ratio of the average cost which the respondents are willing to pay for saving a human life to an EM.