Structural characteristics of karst groundwater system beneath Jinfoshan, Nanchuan district, Chongqing City

The purpose of this work was to clarify hydraulic linkage between every cave and structural characteristics of the karst groundwater system beneath Jinfoshan, Nanchuan district,Chongqing City. Multiple-element tracer tests were conducted in December 2016,in which the Rhodamine B was used as the tracer,and was injected into the Yaochiba sinkhole. A high-resolution online tracer technique was employed to determine the hydraulic connection between the drainage system of Yaochiba sinkhole and Shuifang spring. The duration curves of the tracer show a multi-peak shape, implying existence of a possible single-channel-type karst lake of a certain scale. Then tracers uranine and Rhodamine B were placed at groundwater flows of the Jinfo cave and Yangkou cave, respectively. Using a high-resolution fluorophotometer, online monitoring was conducted at the Yanzi cave. Results indicate that there is s hydroaulic relations between Jinfo cave ,Yanzi cave, and Yanzi cave, respectively, and the duration curves of the tracers all exhibit a jump shap.It is speculated that the underground water passage may be a multiple-channel-type with a certain scale of karst pools.