Abstract: Complex karst system was found in the impervious curtain line of Goupitan Hydropower Station. In view of the karst dam site, we designed and adopted a seepage surveillance system including osmometer, piezometer tubes, measuring weirs and other measures to comprehensively monitor the dam foundation. During the reservoir impoundment, the osmotic pressure of dam foundation has an obvious linear relationship with water level, but the maximum increase of osmotic pressure is only about 20% of that of reservoir water level. After the impoundment, the seepage pressure of dam foundation has no significant relevance with the reservoir water level. Monitoring results show that the overall effect of impervious curtain and karst blocking is obvious. The surveillance system provides a reliable scientific basis for evaluating the project safety.

Key words: karst dam foundation, arch dam, design of seepage surveillance, apparatus layout, monitoring data