Hydrology of the Karst aquifer at the experimental site of Guilin in southern China

The experimental site of Guilin is located near the village of Yaji at the border of the Lijiang Plain (Province of Guangxi, southern China). Within upper Devonian limestones and dolomitic limestones, a karst has developed in accordance with intense fracturing resulting from Mesozoic and Tertiary tectonic episodes. Its morphology is characterized by two major types of karst: a cone karst (peak cluster area) bounded by the Lijiang Plain which comprises a tower or mogote karst (peak forest area). Groundwater discharges from a perennial spring (discharge up to 7 m3 s−1) and three intermittent springs (discharge less than 5 m3 s−1). Some observation boreholes have been drilled on the peak cluster area dolines and on the Lijiang Plain in front of the spring. Tracing experiments in the dolines showed that the dolines are connected with the springs. The apparent flow velocity ranges between 4 and 180 m h−1. Analyses of storm responses of the perennial spring and the variability in time of 18O concentration, pointed out the important role played by the flows occurring in the subcutaneous zone of the peak cluster area.