In the present study, the relation between groundwater fluctuations on a rock slope and the dis-placement of the Mt. Buko rock slope is analyzed. In general, the strength of a rock mass behavior is subject to the influence of water. Rock slope stability consequently declines due to rainfall, especially in limestone terrains, where the rain permeates quickly into the rock mass. The Une Mine has therefore drilled a large number of drainage holes, and installed monitoring devices to measure the groundwater level, in order to analyze the impact of groundwater level fluctuations on the displacement of the rock slope. In addition, the understanding of groundwater fluctuations within a rock slope is important for the purpose of obtaining appropriate locations to drill holes, promoting a more effective drainage. Analysis of a long-term trend in groundwater level fluctuation, especially during and after rainfall, showed that areas with higher groundwater levels were linked to the geological setting of the rock slope, and were probably related to the pre-mining topography of Mt. Buko. This study also revealed that groundwater levels have clear correlations with the displacement of crack gages measured in the observation drift, where the lowering in groundwater levels correspondingly leads to a reduction in the rock slope displacement.
