降雨誘發山區淺層滑坡之臨界雨量研析

Estimation of Rainfall Threshold for Regional Shallow Landslides in a Watershed

陳嬑璇(Yi-Hsun Chen) ； 譚志豪(Chih-Hao Tan) ； 陳勉銘(Mien-Min Chen) ； 蘇泰維(Tai-Wei Su)

《中華水土保持學報》 44卷1期 (2013/03) Pp. 87-96

https://doi.org/10.29417/JCSWC.201303_44(1).0008

摘要

本文分別採用動態水文模式 (TRIGRS)、穩態臨界雨量值 (Qcr) 及臨界雨量線 (CL)三種方法評估集水區發生大規模山崩時之降雨特性，並比較三者之差異及適用性。本文舉高屏溪流域邦腹北溪子集水區因莫拉克颱風引發山崩作為研究案例。分析結果顯示，動態水文模式(TRIGRS) 所得之集水區山崩臨界雨量為328 mm；而採穩態模式 (SHALSTAB) 所得之集水區山崩臨界雨量Qcr 落於50~400 mm/day；另將動態模式分析結果改以統計法繪製成臨界雨量線(CL)，其斜率與國際間其他案例 (I-T 型) 之CL 線相近，但發生山崩所需之降雨強度則明顯較他國案例為高。初步成果可提供相關單位作為防災預警參考運用。

關鍵字

山崩 ； 臨界雨量 ； 雨量門檻值 ； 預警系統

並列摘要

This study applied the dynamic hydrologic model (TRIGRS), the steady-state critical rainfall value (Qcr), and the critical rainfall line (CL) to estimate the critical rainfall for regional shallow landslides. Using the rainfall-induced landslide case of the BangFu North Creek sub-watershed in the KaoPing River watershed during Typhoon Morakot in 2009 as an example, the three methods were compared to discuss their differences and adaptabilities. The analysis results of the dynamic model (TRIGRS) show that the rainfall threshold, defined as the cumulative rainfall at a 50% cumulative area ratio of the landslides in the study area, is around 328 mm. Furthermore, the results of steady-state modeling show that the critical rainfall values (Qcr) vary spatially from 50 to 400 mm/day. Finally, we attempt to plot the result of dynamic model analysis on a rainfall intensity- duration graph and obtain the landslide critical line for the study area. The slope of the critical line is similar to other data from abroad but the rainfall intensity at the landslide occurrence for the study area is much higher than the experience abroad. The preliminary results could be regarded as a good reference for authorities responsible for prevention and mitigation of landslide disasters.

並列關鍵字

Landslide ； critical Rainfall ； rainfall threshold ； warning system.