Hydrogeological structure of the subterranean river system of Yutang and a karst depression reservoir in Yunnan Province, China

Abstract

Abstract Karst groundwater resources are rich, and they have important water supply significance. However, the complex hydrogeological structure of karst areas and the many subterranean river conduits make the development and utilization of karst groundwater resources very challenging. 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 constituted 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 ranged between 40 and 60 m, and the elevation ranged 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.