本計劃重要的創意發想點在於利用直流電阻法監測「時變」之地層電阻率影像，搭配以地表大地電場監測雨水入滲之流動電位訊號，探討可能之邊坡失穩事件機制。本計畫屬過去三年邊坡計畫之延續，過去三年在太平山場址的電場監測工作中，本團隊已獲得令人振奮之結果，可望於第四年度，持續挹注研究資源，以針對土砂災害事件得到進一步水文條件機制上的理解。台灣地狹人稠，平地開發趨於飽和，隨著社會經濟快速發展，過去未使用的山坡地，目前則陸續被開發利用。近年來山坡地的大量開發，破壞了原有之水土保持。台灣島山脈地質岩性大多屬於沉積岩、變質岩，激烈的造山作用致使岩層性質脆弱而易斷裂，復以全年78％的平均降雨量，多集中於五月至十月的颱風季節，因此台灣地區常在夏秋之際，大小土石流屢見不鮮，其所造成的災害案例，更是不勝枚舉。發展土石流預警系統，期在硬體防災措施能完善前，經由預警系統率先警告，以達到保障人民生命財產之安全，乃為山坡地研究之ㄧ重要項目。飽和流體是導致土石流發生的關鍵原因之ㄧ。因此，若能於強降雨其間，即時而連續監控山坡地土壤之含水變化，應能有效監測土石流之發生，未來或許更能進而達到事先預警之功能，以降低災害風險。作為土石流預警指標之一，本計畫過去三年以在太平山崩塌潛勢區建置了大地電場觀測站，透過長期而連續的監測自然電場，配合其他如孔隙水壓等相關監測資料，將有助於瞭解降雨時坡地土壤含水程度的改變，以了解土石流發生機制，並試圖建立土石流預警系統、提升土石流預警之準確率。 ;Narrow island of Taiwan is thickly peopled and its western plain is highly developed. Along with rapid growing in economy, unused hillsides are nowadays successively developed. Large amount of hillsides are exploited in the recent years, which damage the original conservation of soil and water in the hillsides of Taiwan. The rock types are sedimentary and metamorphic in the most of Taiwan mountain areas. Moreover, the mountain building in the active orogeny of Taiwan makes those areas highly fragile and unstable in the typhoon season during May to October when 78% of rainfall averagely happened. Thus, various magnitudes of landslide events are frequently occurred during summer and autumn seasons, causing numerous disasters. An important issue is the establishment of an early warning system for landslide occurrences in the hillsides for protecting the safety of life and belongings to the public. Landslide can be triggered by saturated pore fluid, which is absolutely one of relevant factors. Therefore, continuous real-time monitoring for the saturation of pore fluids becomes critical in the hillsides during rainy seasons. For reducing the landslide hazards, effectively monitoring their occurrences is eager to be prospected and completed in the future. This study is planning to build up a monitoring network of self-potential and geoelectrical resistivity in a high potential area of landslide, for example, the Taiping Mt., Ilan. The self-potential and geoelectrical resistivity monitoring is believed to be highly associated with the pore fluid saturation underground. Combining with other physical measurements available, such as pore pressure data, it would have the greatest improvement and understanding of landslide triggering mechanism and its early warning system.
