Assessment of surface-groundwater interactions using hydrochemical and isotopic techniques in a coalmine watershed, NW China

摘要

The Kuye River is located in Shenfu-Dongsheng coalfield which is the most important energy center in China. The region climate belongs to arid and semi-arid climate with vulnerable ecological environment. Groundwater dewatering for coal mining may cause stream flow reduction in the watershed. Therefore, the effects of coal mining on surface water-groundwater interactions are of great concern in the watershed. In this paper, descriptive statistical method, stable isotope measurements and Piper trilinear diagram are employed to analyze the interaction among river water, groundwater (both in wells used for drinking water and in mine water discharges) and rainwater. The chemical analysis of water samples shows that all the water sources are dominated by HCO3- as anions, by Ca2+ and Na+ as cations. River water has a chemical composition of the NaCa-HCO3 center dot SO4 facies. The chemical composition of mine water discharges is similar to river water within the range of 5km from the river course. Similarly, groundwater samples from drinking water wells that are less than 180m deep and are located within 1km of the river are similar to that of river water. Groundwater recharge analysis shows rainwater is the main source of drinking water recharge when drinking water wells are more than 180m and also the main source for mine water discharge more than 5.5km from the river course.