土石流防災方法成本效益評估方法之研究

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

李欣輯(Hsin-Chi Li)

指導教授 ： 劉格非

國立臺灣大學/工學院/土木工程學研究所/博士(2006年)

https://doi.org/10.6342/NTU.2006.00311

摘要

土石流災害的發生，通常都會造成非常嚴重的損失。因此，每次政府都會積極的投入災後整治的工作，只為了能將災害的損失減至最低。但歷年來的災後整治和相關衍生之問題，已逐漸造成政府財政上的重擔。因此為了讓政府經費使用的更有效率，各種土石流防災方法之成本效益分析就佔了重要的角色。透過成本效益的評估，就能確實掌握各種方法之實際防災效果，提高資源使用的效率。
本文第二章會先透過山坡地管理制度的演進，來了解目前山坡地管理制度的發展，然後再透過實際執行的現況，分析制度執行時所遭遇的問題。第三章是利用經濟學的外部性理論，討論制度執行時的交易成本(主要是協商、補償的成本)，然後依據外部效果內部化的概念，量化此交易成本，藉以評估各種防災方法的執行成本。第四章再依據經濟學中的損失定義，建立一套土石流的災損評估方式，初步估算土石流災害的損失。第五章為針對目前土石流影響範圍的劃定方式做詳細的討論，然後選用較佳的劃定方法，作為土石流影響範圍之計算方法。第六章即開始對各制度進行成本效益的分析。
透過本文所建立的災損評估方法，可以初步將大部份可見的損失予以量化，並且透過量化的分析過程，可以清楚得知每一項損失因子佔總損失的比例，災後的整治就可以針對各項損失的權重進行分配，以達到最適當的安排。再者，利用土石流災損評估之結果，可以直接估算各種防災方法之成本及效益，並透過淨效益的分析，即可求出最佳的防災制度，而此模式所分析的結果，可提供決策單位對於土石流防災制度選擇之參考。

關鍵字

土石流 ； 災損評估 ； 直接損失 ； 間接損失 ； 成本效益分析

並列摘要

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.

並列關鍵字

Debris flow ； disaster assessment ； disaster direct loss ； disaster indirect loss ； cost-benefit assessment

參考文獻

31.林富松，1982，「福利經濟學的先驅—皮古」，允晨出版社。

34.郭長庚，1992，「從山坡地保育利用條例談水土保持法草案研擬經過」，台灣水土保持，第1卷。頁9-13。

38.謝正倫、王志浩、陳禮仁，1992，「花東兩縣土石流現場調查與分析」，中華水土保持學報，第23卷，第2期。頁109~122。

47.周天穎、葉美伶，1997，「水里溪集水區檳榔種植對土壤沖蝕之影響及其經濟分析」，中華水保持學報，第28卷，第2期。頁87-97。

50.臺灣省政府，1998，賀伯颱風紀實（五）交通處主管部。