台湾位于欧亚板块与菲律宾海板块交界带，岩体破碎且地下水丰沛，暴雨期间易肇生坡地灾害。台湾南回铁路沿线多处隧道边坡具有浅岩覆与常渗水的现象，若坡地发生失稳将严重影响铁路营运安全。采用区域地下水经营观念，以水文地质模式分析、评估降雨和地下水对边坡稳定性的短期与长期影响，并透过情境模拟方式评估各种排水配置对隧道边坡稳定性的提升程度，并研拟优化的工程方案以降低致灾风险。

Taiwan is located at the junction area between Philippine Sea Plate and Eurasian Plate. The rock mass is extensively disrupted and abundant in groundwater. Accordingly, the geologic hazards, such as landslides and debris flows, frequently occur, especially during the heavy rainfall. Several tunnel slopes of the SouthLink Line of Taiwan Railway are located under the unfavorable conditions of shallow overburden and water leakage. Therefore, the slope stability will significantly affect the railway operation safety. This study applies the concept of the regional groundwater management to control the short and longterm effects of rainfall and groundwater on the slope stability. We conduct numerical simulations on different drainage patterns so as to increase the slope stability and decrease the hazard risks. Our preliminary results and experience appear to be useful for similar tunnel engineering and regional groundwater management in mountain areas.