結合系集降雨預報之淺層崩塌預警模式

Landslide Warning System Integrated with Ensemble Rainfall Forecasts

何瑞益(Jui-Yi Ho) ； 李光敦(Kwan Tun Lee) ； 黃琇蔓(Xiu-Man Huang) ； 李清勝(Cheng-Shang Lee)

《農業工程學報》 63卷4期 (2017/12) Pp. 79-95

https://doi.org/10.29974/JTAE.201712_63(4).0006

摘要

臺灣山區地形陡峭與地質脆弱，再加上颱風來臨時所帶來的豐沛雨量，往往造成崩塌等坡地災害的發生。欲有效降低颱風與豪雨所帶來的坡地災害損失，除必要的工程方法外，亦須配合適當的災害預警和應變措施，在災前掌握颱風與豪雨動態，因此準確的定量降雨預報技術和崩塌模擬能力，是坡地崩塌預警減災的重要環節。本研究採用系集定量降雨預報技術，彌補單一模式預報的不確定性，以提供未來的降雨預報。此外，研究中採用無限邊坡穩定分析理論與地形指數模式為基礎，建置物理型淺層崩塌預警模式。此模式不僅可考量集水區地文特性，並能分析降雨強度對於飽和水位之變化，進而計算集水區中邊坡安全係數，藉此判斷淺層崩塌災害可能發生的時間。本研究選用台9甲線10.2K上邊坡集水區為示範集水區，以及10場颱風事件資料，逐時進行6小時之崩塌預警。研究中並採用可偵測率、誤報率、預兆得分以及正確率，以此評估結合系集降雨預報之坡面崩塌警戒模式之優劣程度。研究結果顯示，模式對於淺層崩塌發生時間偵測率為0.73以上；誤報率低於0.33；預兆得分0.53以上。冀於往後坡地災害產生前，能提供相關單位作為災害應變之參考依據，以保障民眾生命財產的安全。

關鍵字

系集定量降雨預報 ； 崩塌預警模式 ； 飽和水位變化

並列摘要

Taiwan is prone to hillslope disasters in the mountain area because of its special topographical, geological, and hydrological conditions. During typhoons and rainstorms, severe shallow landslides frequently occur. To mitigate the impact of shallow landslides, not only the structural measures are necessary, but also adequate warning systems and contingency measures must be executed. Hence, precise precipitation forecasts and landslide prediction are the most important measures in practice. To account for inherent weather uncertainties precipitation forecasts based on ensemble model predictions was adopted in this project instead of using a single model output. A shallow landslide prediction model based on infinite-slope model and TOPMODEL was developed. In considering detail topographic characteristics of the subcatchment, the proposed model can estimate the change of saturated water level during rainstorms, and then link with the slope instability analysis to clarify whether shallow landslides can occur in the subcatchment. The subcatchment on No. 9A Highway at 10.2 K was selected as the test sites for landslide predictions with a lead time of 6 hours. Hydrological data and landslide observed records from 10 typhoons events were used to verify the applicability of the model. Four indexes including the probability of detection (POD), false alarm ratio (FAR), and threat score (TS) were adopted to assess the performance of the model. The results indicated that the POD for the landslide prediction by using the proposed model was higher than 0.73, the FAR was lower than 0.33, and the TS was higher than 0.53. It is promising to apply the proposed model for landslide early warnings to reduce the loss of life and property.

並列關鍵字

ensemble rainfall forecasts ； landslide warning system ； changes in saturated water levels