With well over 1 million km2 of carbonate rocks exposed at the surface, and a history of exploitation spanning in excess of 2000 years, the Chinese probably have more experience than any other people in developing the water resources of carbonate aquifers. Interestingly, many of the smaller scale projects are carried out by local farmers and co-operatives, with little recourse to the advice of professional engineers and hydrologists, although even in large regional schemes, much local expertise and labour is involved (see for example Hegtkcar 1976). While recently some of the Chinese work on karst hydrology has become available in the west (Song 1981; Song et al 1983; Yuan 1981, ) much of the practical experience resulting from these local and small scale developments remains unpublished even in China. We were therefore very fortunate to be able to examine the engineering works associated with the Guanyan cave system, just south of Guilin, Guangxi Province, SE China, during a recent joint venture with the Institute of Karst Research, Ministry of Geology, Guilin.
The Guanyan (Crown Cave) system is developed in a sequence of relatively pure, predominantly finegrained limestones and dolomites over 2600 m thick, and ranging from Devonian to Carboniferous in age (Yuan 1980). These are folded into thrust faulted, NW-SE-trending folds, but dips are generally less than 30°. The underlying impermeable shales, siltstones and sandstones form a mountainous terrain rising to 1400 m above sea-level east of the limestone, and provide the headwaters for streams feeding into the caves (Fig.