Hydrochemical and Isotopic Explanations of the Interaction between Surface Water and Groundwater in a Typical-Desertified Steppe of Northern China

Abstract

The Tabu catchment, a typical-desertified steppe in China, was selected as the study area to qualitatively analyze the interaction between surface water (SW) and groundwater (GW), and an integration of hydrochemical analysis and isotopic techniques was applied. The results show that the ion contents in SW and GW increased from upstream to downstream, and the hydrochemical evolutions were both controlled by rock weathering and influenced by evaporation. The δD–δ18O lines of SW and GW were δD = 5.14δ18O − 24.68 and δD = 6.89δ18O − 5.81, respectively. Along the I–I′ profile, the contents of most indices, δD and δ18O in SW and GW both showed increasing tendencies. All of the similarities in the hydrochemical characteristics and isotopic techniques indicated that SW was recharged by GW. The δD–δ18O inconsistency in SW and GW samples from midstream and downstream areas indicated that SW did not recharge to GW in these areas and was consumed by evaporation or replenished the moisture in the vadose zones. The runoff decreased, which was mainly caused by excessive exploitation of GW and a decline in the GW level. This study deepens the understanding of the hydrological cycle and provides guidance for the optimal combined utilization of SW and GW.

Hydrogeochemical Behavior of Shallow Groundwater around Hancheng Mining Area, Guanzhong Basin, China

“…The study of the hydrochemical composition and type of groundwater in a region can describe the hydrogeological history of the area [10], elucidate the origin and formation of the groundwater, and provide a visual evaluation of the groundwater quality to assess its availability or risk level. Currently, hydrogeochemical methods have made great progress in groundwater research, and the combined use of hydrochemical-type methods [11], isotope methods [12,13], thermodynamic methods [14], and multivariate statistical methods [15] has solved the quantitative and qualitative problems of hydrogeochemistry, and the hydrochemical method and isotope method are the most basic and practical methods. The hydrochemical-type method is mainly used to judge the qualitative study of the analysis of the major ion sources of groundwater in the target region, i.e., to analyze where the major ions in the groundwater come from in conjunction with the proportionality between the components, and to reveal the reaction processes of the major ions in the groundwater.…”