Seepage Characteristics of Karst Water System Using Temperature Tracer Technique.

In order to reveal the hydrodynamic characteristics of the karst aquifer system, the water temperature dynamic data of a hydrological year in the direct recharge area of Jinan spring area were analyzed using the temperature tracer method, and the runoff intensity of karst water was estimated. The results revealed that, affected by the regional groundwater flow, the vertical temperature profile of the study area consists of four types, a gradual cooling type, a gradual heating type, a temperature‐increasing type, and "S" type. Based on these four geothermal types, three heat transfer models adapted to the region were developed. The inflection point method is used to discriminate the horizontal runoff channels of the three depth segments in the Ordovician strata in the recharge area, and the shallow groundwater horizontal runoff intensity is greater than the deep. According to the calculation of the thermal transport model, the Ordovician limestone in the direct recharge area of the spring area is shallow (at a depth of 100 m), and the vertical flow velocity of the groundwater is around 1.28 × 10−7–3 × 10−6 cm/s, and the flow rate is slow. Based on the field tracer test, the visual flow of the karst water system was found to range between 29.41 and 115.02 m/day, indicating that the karst water is dominated by horizontal motion. Since the method of temperature measurement in the hole is relatively simple, the temperature change signal could be used to reveal the seepage characteristics of the groundwater. Key Points: The temperature change signal could be used to reveal the seepage characteristics of the groundwaterThe groundwater tracer technology confirmed that the karst development and seepage characteristics of Jinan spring area have heterogeneous characteristics [ABSTRACT FROM AUTHOR]