Experimental Study on the Boundary of Karst Spring Basin: Take Ji'nan Spring Basin as an Example

The accurate determination of spring area boundary position and boundary property is an important link to establish a correct hydrogeological conceptual model, and is the fundamental guarantee of the accuracy of groundwater resource calculation results in the spring area. In view of the two perspectives of the east-west boundary of Jinan spring basin, the sand tank model of the fault-watershed region was built based on the characteristics of karst aquifers. The experimental scenarios were dominated by changing the precipitation intensity and duration time. The experiment results under different scenarios were analyzed and the characters of the boundary were preliminarily investigated. The results show that about 30% ∼ 40% of the atmospheric precipitation is converted into surface runoff, and 50% ∼ 60% of that is converted into fissure karst water. The water balance can be correctly calculated only by accurately identifying the water flow direction and amount of sources and sinks of the region.