Isotope features and supply sources of groundwater in the Yarkant River drainage area, Xinjiang

Abstract：On the basis of hydrogeological investigation of the Yarkant River drainage area, Xinjiang, the authors analyze the sources of groundwater recharge according to the variations of D, 18O and T values in different regions and at different depths, solve the problem that is difficult to solve with the traditional research approach and provide a new idea for the study of the origin and spatial distribution of groundwater in arid areas. The results indicate that：(1) the groundwater is not derived from direct infiltration of precipitation but from seepage recharge of surface water；(2) there are two independent groundwater circulation systems which receive the waters of the Yarkant River and Tiznap River respectively；(3) the origins of phreatic water and confined water are the same, belonging to a unified groundwater system；and (4) in the sloping plain area the groundwater runoff is strong and groundwater movement is mostly horizontal, while in the fine soil plain area, the groundwater runoff is sluggish with vertical evaporative movement predominating and the runoff direction is closely related to the flow direction of surface water.