Study on the Hydrogeological Structure of a Karst Subterranean River and Seepage of a Karst Reservoir: A Case Study of the Yibasan Reservoir in Yunnan Province, China

Abstract

Karst groundwater resources are rich, and they have important water supply significance. A karst reservoir is a means of exploiting and utilizing groundwater resources, but because of the complex hydrogeological structure and underground river pipeline in a karst area, the seepage problem of the reservoir is extremely serious. Therefore, the Yibasan Karst Reservoir (YKR) was selected as the focus of this study. The hydrogeological structure of the subterranean river system of Yutang (SRSY) was identified and the hydraulic connections between the subterranean river conduits were determined using tracer experiment and groundwater dynamic monitoring. Furthermore, the development location and depth of the karst seepage zone of the YKR were determined using geophysical exploration. The results showed that there were three subterranean river conduits in the SRSY, and there was no hydraulic connection. The northern and southern pressure and torsion faults on the sides constitute the impervious boundary of the SRSY, which provided good catchment conditions for the formation of the YKR. Additionally, the northern and main conduits of the SRSY provide a sufficient groundwater source for the YKR. Moreover, the development width of the karst seepage zone of the YKR ranges between 40 and 60 m, and the elevation ranges between 1275 and 1355 m. The research results not only provide an effective basis for the treatment of the karst seepage problem of the YKR but also provide an important reference for the development and utilization of groundwater resources in similar karst areas.