降雨量與誘發山崩發生率之關係

The relationship between rainfall and the occurrence rate of induced landslides

邱奕勛(I-HSUN CHIU)

指導教授 ： 李錫堤

國立中央大學/地球科學學院/應用地質研究所/碩士(2012年)

摘要

降雨誘發山崩是台灣目前主要的山崩災害，因此探討不同集水區之降
雨量與誘發山崩之關係有其重要性。近年山崩潛感分析開始加入雨量因子
進行統計，為瞭解雨量因子是否有其物理意義，因此挑選若干個設有雨量
站的小集水區，觀察降雨量與誘發山崩發生率之關係。本研究在全台灣的
沉積岩、板岩、變質岩三個不同的地質區中，選取適當的次集水區作為分
析單元，測繪不同降雨事件之誘發山崩，並分析誘發山崩發生率與雨量因
子之關係。降雨因子包括：最大時雨量、總雨量、平均降雨量強度、降雨
延時以及最大3、6、9、12、24 小時雨量。誘發山崩發生率則以崩壞比表
示；某一降雨事件分析單元內誘發山崩面積與該單元面積之比率稱為崩壞
比。
每一降雨事件之崩壞比與某一雨量因子之關係以最小平方法進行線性
一次迴歸，發現各研究區R2 值結果良好，雨量因子與崩壞比具有正相關
性，證實雨量因子作為山崩潛感模型促崩因子有其物理意義。本研究採用
R2 值達0.5 以上之降雨誘發山崩崩壞比曲線，將曲線於橫軸之截距定義為
該研究區降雨門檻值，發現各研究區的確有門檻值現象存在。同時證明，
利用線性一次迴歸已足夠表示降雨量雨誘發山崩發生率之關係。本研究發
現各地質區雖無統一的崩壞比曲線斜率及降雨門檻值，但是相鄰或者距離
較近的地區較有相似的崩壞比曲線斜率及降雨門檻值。

關鍵字

降雨門檻值 ； 集水區 ； 淺層山崩 ； 雨量 ； 降雨誘發山崩 ； 崩壞比

並列摘要

Rainfall-induced landslides is a major landslide disaster in Taiwan. To
study the relationship between rainfall and induced landslides at different
drainage basins is important. In recent years, landslide susceptibility analysis
began to use rainfall as a triggering factor in statistics. For realizing the
physical meaning of rainfall factor, we select a number of small drainage basins
where a rainfall station in available to observe the relationship between rainfall
and the occurrence rate of induced landslides. This study selects 17 study areas
to map induce landslides of each rainfall events and to analysis the relationship
between rainfall and the occurrence rate of induced landslides from the
sedimentary terrain, the slate formation and the metamorphic complex in
Taiwan. Rainfall factors include maximum hourly rainfall, total rainfall,
average rainfall intensity, rainfall duration, and maximum 3, 6, 9, 12, 24 hourly
rainfalls. We present the occurrence rate of induced landslides by the landslide
ratio; the ratio of landslide area and total area in each study area.
The correlation between the landslide ratio and a rainfall factor is positive.
This supports that rainfall as a triggering factor used in a landslide
susceptibility analysis is physically meaningful. This study uses a simple linear
regression model to fit the relationship between the landslide ratio and a rainfall
factor in each study area. The goodness of fit for the regression model is
generally acceptable. We selected those models with R2 value larger than 0.5 to
find out the intercept of the best fit line and the horizontal axis and to define a rainfall threshold. At the same time, we found that the use of a simple linear
regression model is good enough to interpret the relationship between rainfall
and the occurrence rate of induced landslides. Finally, we observe the landslide
ratio curve and the rainfall threshold in each geologic province. Although the
landslide ratio curve and the rainfall threshold are not consistent in a whole
geologic province, they are similar in the adjacent or the closer study areas.

並列關鍵字

shallow landslide ； drainage basin ； rainfall threshold ； rainfall ； rainfall-induced landslides ； landslide ratio

參考文獻

譚志豪、陳嬑璇、冀樹勇（2009）以定率法評估集水區山崩臨界雨量，中

林美聆、陳天健、林鴻州、游文輝（2003）台北市崩塌警戒模式訂定方法

Caine, N. (1980) The rainfall intensity-duration control of shallow landslides

38(12), 267-272.

probability of landslide occurrence and rainfall. Can. Geotech. F., 34,