地震或降雨誘發崩塌之崩塌特性探討

The Discussion of the Characteristic of Landslides Caused by Rainfall or Earthquake

陳樹群(Su-Chin Chen) ； 吳俊鋐(Chun-Hung Wu) ； 王雁平(Yen-Ping Wang)

《中華水土保持學報》 41卷2期 (2010/06) Pp. 94-112

https://doi.org/10.29417/JCSWC.201006_41(2).0006

摘要

台灣由於地形陡峻及地質脆弱，易造成崩塌及土石流等土砂災害，近年更受地震及豪雨影響，山區土砂災害頻傳且造成重大傷亡及財產損失。本研究利用數值高程模型探討崩塌深度與崩塌面積之相關性，期望能利用兩者關係，進而推估崩塌土砂量。本研究試區爲北台灣之石門水庫集水區及中台灣之大甲溪集水區，利用降雨事件前後期之崩塌地，針對此兩個集水區做崩塌面積分布之探討，求得其崩塌規模與頻率關係呈現冪次關係，根據研究分析結果：冪次關係之κ參數大小與崩塌個數多寡相關，而β參數值則跟區域崩塌相關特性有關，台灣地區之β參數值大多介於1.6~2.0之間；根據兩集水區歷年崩塌面積增加率，本研究認爲大甲溪集水區於2004年之崩塌地形成主因乃爲1999年集集地震，但石門水庫集水區於2004年之崩塌地形成主因則爲2004年艾利颱風。本研究也利用5m×5m之數值高程模型與崩塌地圖層套疊，探討其地形變遷，再利用面積深度法及坡度深度法進行統計分析，探討崩塌深度與崩塌面積的關係式。

關鍵字

崩塌深度 ； 冪次關係 ； 土砂量

並列摘要

Landslide is frequently induced by rainfall and earthquake in mountainous area in Taiwan. The study discusses the relationship of slope, landslide depth and landslide area by calculating the topography changes from the Digital Elevation Model (DEM) extracted from landslide areas induced by rainfall events in Shihmen reservoir watershed and Da-Jia river watershed in Taiwan. The study developed the power law formula in the landslide frequency-area distribution. The coefficient κ and β in the power law formula are related to the amount of the landslide sites and the characteristic of the landslide. According to the analysis in the study and other references, the value of β is between 1.6 and 2.0 in Taiwan. According to the analysis result, the landslide distribution in 2004 in Da-Jia river watershed were mainly caused by Chi-Chi earthquake in 1999, but in Shihmen reservoir watershed were mainly caused by Typhoon Aere in 2004. The topography changes from 5m×5m DEM in landslide areas before and after rainfall events was evaluated to develop the relationship between the landslide depth and landslide area by landslide area-depth method and slope-depth method and estimate the landslide volume yield caused by a rainfall event.

並列關鍵字

landslide depth ； power-law ； landslide volume