從坡地聚落的普查看台灣地區土石流潛勢溪流與保全住戶之低估

Underestimation of the Number of Streams of Potential Debbris Flow and Households for Preservation According to the General Survey of Slope Settlements in Taiwan

林祥偉(Shyang-Woei Lin)

《工程環境會刊》 33期 (2014/07) Pp. 17-25

https://doi.org/10.6562/JEE.2014.33.2

摘要

台灣交通網絡、居住型態均受山地、河川所限制，在山崩、土石流等自然作用力下，使得不少偏遠及山區的村落，位處於敏感度高的邊際土地上。爰此，農委會對山麓谷口地帶，劃設土石流潛勢溪流，並建立土石流潛勢溪流下游的保全戶名單，期能在災害發生前，採取必要的疏散避難措施。但是，坡地災害發生機制，受到周遭地質、地形和人文活動的影響，坡地與谷口的聚落安全，不僅僅侷限在農委會關注的土石流潛勢溪流下游。為彌補農委會僅針對土石流潛勢溪流下游保全戶之不足，以花蓮縣的坡地安全普查資料為基礎，全面檢視山麓谷口地帶的潛在危險住戶。這個研究結果顯示，土石流潛勢溪流保全戶與坡地潛在危險住戶差距高達10倍之多，若以花蓮縣的實例來運用到全台灣的推估，全台灣9500平方公里的山坡地區域，土石流潛勢溪流與保全人數，至少需要從至2013年10月為止1664條49,859人，增加5至10倍，才能含跨所有坡地潛在危險的住戶。

關鍵字

土石流潛勢溪流 ； 保全住戶 ； 坡地安全

並列摘要

Transportation network and residence type in Taiwan are subject to constraints of mountains and rivers. Under the impact of natural forces such as landslide and debris flow, many villages in remote and mountainous areas are located in marginal land of high geological sensitivity. For this reason, the Council of Agriculture has designated streams of potential debris flow in foothills and valleys, and established the list of households for preservation in the downstream areas of such streams, expecting to take necessary disaster relief and evacuation measures before disaster occurs. However, the slope disaster causation mechanism is subject to the impact of surrounding geology, topography and human activities. The safety of settlements in the slope and valley is not limited in the downstream areas of streams of potential debris flow concerning the Council of Agriculture. To make up for the inadequacy of the Council of Agriculture, this study comprehensively reviewed potentially dangerous households in the foothills and valleys. According to the data of the General Survey of Slope Safety in Hualien County, this study found that, by estimation of Taiwan based on the situation of Hualien County, people to be protect from the streams of potential debris flow in the 9500 square kilometer slope area in Taiwan should increase by 5 to 10 times from the current 49,859 people and 1664 streams.

並列關鍵字

Streams of Potential Debris Flows ； People to be Protect from the Streams of Potential Debris Flow ； Foothills and Valleys’ Preservation