ABSTRACT
Epikarst in South West China is important to the hydrological regime and consequent environmental problems in the area. A slope with bare epikarst in the Fengcong area near Guilin has been studied to understand the hydrological function of the surface layer. A physical model is set up based on data from multiple methods of field observation, tracer tests and monitoring. The water budget is used for comparing different hydrological links such as canopy interception, soil moisture deficit, runoff generation and leakage/infiltration in the slope. Although in the top layer of the slope, epikarst zone and soil infiltration dominates, but surface runoff still happens during extreme storms and changes into mostly vadose flow within a very short distance. Results from this study show that the drainage area of a vadose stream varies depending on climate. In the monsoon period it is about 491 m2, which is larger than that in typhoon period. However the average rainfall interception depth, which is the threshold for flow generation in both periods, is about 16 mm. The threshold derives mainly from the canopy interception, soil moisture deficit, and epikarst storage.
