IMPACTS OF YONGDING RIVER ON THE XISHAN KARST AQUIFER AND YUQUAN SPRING IN BEIJING, CHINA

The karst water mixed with infitrated river water shows high Na, Cl and O-18 values and can be used to indicate the distribution of the infiltrated river water in karst aquifers. Individual flow path for three recharge sources was identified in the Xishan karst aquifer in Beijing, China using hydrochemical and isotopic methods. The recharge of rainfall in the Junzhuang area had two flow routes:one flows eastwards to the Yongfengtun; another flows southeastwards along east of the Yongding fault. The recharge of rainfall in Tanzhesi area flows along north of the Babaoshan fault northeastwards Sijiqing. The Yongdingriver infiltrates in the Junzhuang area and flows along the Yongding fault in the direction of southeast and turns to the diction of northeast near Gucheng, along a buried fault which is revealed this time. River water plays an important role in recharge to the karst aquifer and can be used to restore depleted karst flow systems by increasing the flow and infiltration of river water.