摘要
為強化土石流防災應變,水保局自2005年開始在降雨強度I=10 mm/hr條件下,採總有效累積雨量R_(70)當作土石流警戒發布標準,並以50mm為一個級距,訂定各鄉鎮區之土石流警戒基準值。而為確保資料定期更新及提昇土石流警戒發佈之準確度,2014年計畫中提出3縣市4鄉鎮區的警戒值調整建議,同時檢討參考雨量站之適用情況,對於缺乏雨量站地區,提出53處增設地點建議,並針對2005~2013年間之土石流警戒發布成效進行檢討。此外,為應極端氣候下之崩塌地災害,本研究針對2013年所提出之崩塌預警模式(LRTI模式),考量未來導入實際運用之可行性,進行降雨參數與警戒線訂定方式之檢討與調整,並透過歷史實際崩塌事件驗證與本年度3場實際降雨測試。
Soil and Water Conservation Bureau(SWCB) applied rainfall- based debris- flow model(RTI model) for evaluating the debris- flow occurrence potential which is defined as the product of the rainfall intensity I(mm/hr) and the effective accumulated rainfall Rt(mm) in 2003.The R_(70)-value was set as rainfall critical value for evacuation in 2005,which was the accumulated rainfall value calculated from the RTI_(70)-value by taking the rainfall intensity I being 10 mm/hr.Furthermore,for easier applying,one takes every 50 mm as an interval of the critical value of accumulated rainfall(R_(70)) to determine the debris-flow warning threshold for every township in Taiwan.For enhancing the accuracy of debris-flow warning system,this project adjusts the debris-flow warning criteria under the consideration of new rainfall events,new debris-flow events,new debris-flow prone streams and the effect of earthquake.The applicability of reference rainfall- gauges are also analyzed and discussed.Besides,the efficiency of the debris- flow warning issued in the typhoon and extremely heavy rain events are evaluated during 2005 ~ 2013.In the recent decades,rainfall characteristics have obviously changed with global climate change in the whole world.A single debris-flow warning system is perhaps insufficient to deal with the threats.Thus,SWCB proposed a landslide rainfall triggering index(LRTI model) for the occurrence of landslide disasters in 2013.For estimating the feasibility of practical application,this study reviews rainfall parameters,weighting factor of antecedent precipitation,and the method of setting the critical line by analysis of historical landslide records and practical operations during rainfall.The results show LRTI model can provide as a reference of landslide early warning.
引文
[1]李佳純.降雨觸發崩塌的可能性評估研究-以高屏溪流域為例[D].臺灣:成功大學水利及海洋工程研究所,2012
[2]陳振宇.以雨量為基礎之土砂災害警戒系統成效評估-以臺灣及日本為例[J].中華水土保持學報,2013.44(1):49-64
[3]詹錢登、李明熹.土石流發生降雨警戒模式[J].中華水土保持學報,2004,35(3):273-283
[4]楊介碩.高雄壽山地區岩石力學特性調查及坡面滑動觀測[D].臺灣:成功大學土木工程研究所,1989
[5]「水土保持局農業委員會」.以降雨因子進行土石流警戒基準值訂定[R].2005
[6]「水土保持局農業委員會」.2014年土石流警戒基準值檢討與更新[R].2014
[7]国土技術政策総合研究所国土交通省.土砂災害警戒情報運用结果檢証手法[R].2004。
[8]#12
[9]氣象廳国土交通省.土砂災害警戒情報の運用成績[R].2013。
[10]Jan Chyandeng,Lee Minghsi,Wang Jishang,et al.A rainfall-based debris-flow warning model and its application in Taiwan[C].International Conference on Slope Disaster Mitigation Strategy,2004;111-119.
[11]Jan Chyandeng,Lee Minghsi.A debris-flow rainfall-based warning model[J].Journal of Chinese Soil and Water Conservation,2004,35(3):273-283(in Chinese).
[12]Osanai N,Shimizu T,Kuramolo K,et al.Japanese early-warning for debris flows and slope failures using rainfall indices with Radial Basis Function Network[J],Landslides,2004,7:325-338