降雨、地下水位及土壤雨量指數之關係與警戒值探討-以梨山崩滑區為例

The Relationships among Rainfall,Ground Water Table,Soil Water Index and Warning Threshold-A Case Study of Lishan Area.

陳貽婷(YI-TING CHEN)

指導教授 ： 林基源

朝陽科技大學/設計學院/景觀及都市設計系/碩士(2017年)

摘要

梨山地區，自民國79年起，發生大規模滑動，之後每年出現5到10公分的變位。歷經民國88年921地震及後續颱風影響，尤其是民國93年敏督利颱風(七二水災)過後，原地滑治理區外圍，包括台7甲線上的松茂部落及台8線上的老部落、新舊佳陽部落等地，都有新的地滑地災害。民國102年，520豪雨及蘇力颱風造成大梨山幾處地區明顯位移之影響。

梨山地區地滑主因係由大量雨水入滲而引起地下水位的變化為其主要誘因，本研究以中央氣象局梨山雨量站和梨山地區地滑監測站-梨山精華區B4、新佳陽地區J1、老部落地區L1及松茂地區S1等四個自動監測站之逐日雨量資料，分析民國101至民國105年近五年梨山地區季節雨量之變化，以陳樹群等人（2013）、曾國維(2003)及劉于名（2016）之研究結果作為參考依據，運用筒狀模式分析19個颱風事件，探討事件中三筒層水位變化特性，再以不同之數據組合繪製警戒範圍，探討地層位移發生之情況與土壤雨量指數變化關係，最後提出梨山地區地滑區域之警戒值，並將結果提供於後續防災規劃上及後續研究之依據及參考。

在與投89鄉道崩塌案例累積雨量相比之下，得知梨山地區平均累積雨量不到投89鄉道崩塌案例平均累積雨量二分之一。由於此區域降雨量較少，再將地下水位高程加入分析整合後，本研究所得出之結果，分別以24小時累積雨量、土壤雨量指數與地下水高程變化量將梨山地滑地區域分界為正常、警戒和行動等三個階段；24小時累積雨量警戒預警基準值設為150mm，行動預警基準值設為250mm，土壤雨量指數警戒預警基準值設為125mm，行動預警基準值設為250mm，地下水相對高程變化警戒預警基準值設為4m，行動預警基準值設為9m，建議以此作危險預警基準值。

關鍵字

筒狀模式 ； 連續性降雨 ； 梨山崩滑地區

並列摘要

Since 1990, large-scale sliding has occurred in Lishan area, and 5 to 10 cm displacement happened annually. After 921 earthquake in 1999 and follow-up typhoons, especially Typhoon Mindulle (July 2nd Floods) in 2004, new landslide disaster stroke the surroundings of original regulated landslide area, including SongMao District on Provincial Highway 7-A, Lao & XinJiuJiaYang Disctrict on Provincial Highway 8. In 2013, May 20th torrential rain and Typhoon Soulik brought about detectable slide on some areas of Greater Lishan.
Sliding in Li-Shan District mainly resulted from underground water level variation, which’s owing to osmosis of heavy rain. This study takes Central Weather Bureau Li-Shan Rainfall Station and Li-Shan Sliding Monitor Stations - Li-Shan Main ZoneB4, New JiaYang AreaJ1, Old Tribe AreaL1, and Song-Mao AreaS1, the rainfall/ per day data from these four automatic monitor stations, with the aim to analyze the seasonal rainfall variation in Li-Shan Area within 5 years (2012-2016); takes CHEN SHU QUN and so on (2013), TSENG,KUO-WEI (2003), and LIU,YU-MING (2016)’s research for reference, applies tank model to analyze 19 typhoon cases, to investigate the three-tank layer variation characteristic of each case, and use different data combination to illustrate the warning zone, to investigate the relevance between stratum sliding occurrence and soil water index’s variation. Finally, the study concludes a warning value in Li-Shan Sliding Area, and provides the result to follow-up disaster prevention plan and study as a reference.
Compared with the accumulative rainfall in Nantou 89 Country Road collapse case, we could know that the average rainfall in Li-Shan Area is less than half rainfall in former case. Due to less rainfall on this area, and takes elevation of underground water level into analysis and integration, the study concludes an outcome- dividing Li-Shan sliding area into three stages: normal, alert and action with 24-hour rainfall data, soil water index, and variation of underground water elevation; the alert warning value of 24-hour accumulative rainfall is set as 150mm, and action warning value is set as 250mm; soil water index alert warning value is set as 125mm, and action warning value is set as 250mm; the alert warning value of variation of underground water level is set as 4m, and action warning value is set as 9m, it’s more proper to map out the warning zone by adopting these numerical value.

並列關鍵字

Lishan area ； Continuous rainfall ； Tank model

參考文獻

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