使用雷達回波降雨資料建立西南部山坡邊坡滑動預警系統

邊坡滑動或破壞具有復發性，在地質條件不變及無人為擾動因素之條件下，當地下水位抬升至臨界狀態，過去曾發生變動之邊坡勢必極有可能再次位移及崩壞。而位於歐亞板塊及菲律賓海板碰撞所形成之臺灣，地形高聳地質複雜，加上近年極端氣候的影響，颱風豪雨侵襲屢見不鮮，導致邊坡破壞頻率大幅增加。本研究選定台灣西南部一處曾經崩塌過之邊坡－市道175道25K+500處（原台174縣道50K+500），首先蒐集場址地質資料以及附近雨量外，同時進行地層鑽探及地電阻施測，藉此了解邊坡地層分佈狀況。也於上下邊坡處設置傾斜觀測管、地下水位計、地表伸縮計、傾度計等監測儀器，用以觀測地下水位變動及邊坡變動之趨勢以及決定臨界地下水位方法等，探討降雨引致地下水位變動以致邊坡破壞的關係，並進而研究使用中央氣象局提供之氣象雷達回波資料，整理出雷達回波強度與降雨之迴歸式，結合臨界地下水位以及邊坡穩定性之關係，以其作為建立邊坡崩壞預警系統的參考依據。

關鍵字

邊坡破壞；雷達回波；預警系統

並列摘要

Slope failure can be re-activated. A landslide fails when the groundwater table reaches its critical state without changing the geological conditions and artificial disturbances. Taiwan is located at the boundary of Euro-asia and Philippine plates. The frequency of slope failure caused by the heavy rainfalls from typhoons is increasing because of the mountainous topography, complicated geology, and the impact of climate change. This study investigates the slope stability at the Tainan 175 highway 25k+500 (originally Tainan 174 highway 50k+500) by gathering local geological data and the rainfall data from the neighboring rainfall station. In addition, additional borehole drillings and electric resistivity survey are conducted to clarify the distribution of rock formations. The critical groundwater table is determined based on the groundwater fluctuation and ground deformation by the monitoring of inclinometers, groundwater, extensometers, and tilter meters. Then, the relationship between groundwater table and slope deformation can be clarified. After defining the regression equation between the reflectivity of the meteorological radar and the rainfall, a slope failure warning system can be established by integrating the critical groundwater table and slope stability.