Significance and dynamics of drip water responding to rainfall in four caves of Guizhou, China

In rainy season, NaCl is adopted to trace sources of cave drip water, time scales of drip water responding to precipitation, and processes of water dynamics in four caves of Pearl watershed in Guizhou, China (Liangfeng cave in Libo, Qixing cave in Duyun, Jiangjun cave in Anshun and Xiniu cave in Zhenning). Because of the variety of karst cave surroundings, interconnections of water transporting ways, water dynamics processes etc., time scales of drip-water in four caves responding to rainfall is 0–40 d. According to the characteristics of water transport in cave roof, pathways of water movement, types of water head etc., drip water of four caves can be divided into five hydrodynamics types. The differences of time scales, and ways of water-soil and water-rock interaction during water transporting in cave roof make it difficult to correctly measure speleothem record and trace material sources. In addition, there exist great differences in water dynamic conditions among the four caves. So the interpretation of the paleoenvironment records of speleothem must be supported by the understanding of hydrodynamics conditions of different drip sites. Based on the data got from drip sites in four caves, drip conductivity accords with precipitation, which indicates that element contents in speleothem formed by drip water record the change of karst paleoenvironment. But results of multi-points study are needed to guarantee the correctness of interpretation.