The cost-benefit assessment of mitigation methods for debris flow hazards

Debris flow disasters are usually accompanied by a serious loss of lives and property. The related recovery, prevention, and mitigation measures have put a heavy financial burden on the government. A usable and practical assessment methodology has to be developed in order to financially evaluate proper countermeasures. If the assessment can be done accurately, the government can have a better understanding of the overall mitigation measurements in the area, including preventative measures and rescue procedures. This is the aim of this paper.
Chapter 2 will discuss the procedures for management systems of mountainsides. Through the analysis of present situations, we will assess the management problems related to dealing with debris flow. Chapter 3 will introduce the theory of externality, which is discussed in the economic arena, for dealing with the problems of management systems. Chapter 4 will describe an assessment method to quantify debris-flow hazards. During this process, which category will bear the greatest loss should be obvious. This method can also be used for the evaluation of mitigation measures. Furthermore, this assessment method can be used before the disaster actually occurs. Chapter 5 will discuss the method for deciding where the affected areas lie. In general, numerical simulation is considered more accurate, provided that the input is not faulty. The program Debris-2D (Huang, 2003) was used in delimiting the affected area of debris flow in this paper. Chapter 6 will take some cases of debris-flow disasters as examples for verification of the theory.
Finally, using the research of this paper, we can take the results to determine the debris-flow hazard defense magnitude; it can be applied to weigh the benefits of any kind of prevention works dealing with debris flow. For example, once the detailed losses of the disaster can be assessed, the benefits of the prevention works can be relatively calculated, which means a reduction in disaster loss. Then, by applying the method of cost-benefit analysis to every different prevention work, we may more clearly understand which methods are most effective. Thus, through the application of this model, not only can we promote the effects of debris flow hazard defense, but also reduce the squandering of resources used against natural disasters. In addition the loss of residents’ lives and property can be lowered.