A SIMULATION STUDY ON THE EVOLUTION OF GROUNDWATER CIRCULATION SYSTEMS IN CENOZOIC BASINS OF NORTHERN CHINA

Three Cenozoic basins-the Qaidam basin, the Weihe graben-type basin an d the North China plain-which are different in climatic conditions, ge ological settings and run-off types, are selected for the study. Based on an analysis of background information of the transect along the mi ddle-latitude region, studies of groundwater dynamics, geochemistry, s imulation of water circulation of the main elements as well as isotopi c chronology, the information on global changes is collected, the form ation of groundwater circulation systems and their evolution under sta cked impacts of natural conditions and human activities are discussed, and a correlation is made between the evolutionary features of the ab ove systems in these basins since 25 ka B.P. All these have laid a goo d foundation for further generalizing the evolutionary model of land w ater in northern China.