Stable isotope evidence for identifying the recharge mechanisms of precipitation, surface water, and groundwater in the Ebinur Lake basin.

Arid areas cover more than one third of global land, and as such, water resources are vital for this fragile ecosystem. In order to reveal the recharge mechanisms among different water bodies in arid areas, precipitation, surface water, and groundwater were sampled in the Ebinur Lake basin, Xinjiang, China, and the isotopic values for hydrogen and oxygen were measured. The stable isotope values of precipitation showed significant seasonal variation, with minimum values in the winter, medium values in the spring and autumn, and maximum values in the summer. The slope and intercept of local meteoric water line were both lower than that of global meteoric water line, indicating subcloud evaporation effect. The vapor source of precipitation was dominated by the westerlies, but the regional re-evaporation vapor accounted for some proportions as well. In the Bortala River and Jinghe River, the stable isotopic values varied spatially, tending to be enriched with the river flow. The stable isotopic values for lake water were significantly higher than those of river water, which reflected a stronger evaporation and concentration effect of the lake water. The stable isotopic values of groundwater featured similar spatial variation compared to the river, and phreatic water evaporated to some extent. In the Bortala River, owing to its specific hydrogeological structure, the exchange rates between the groundwater and the river water were higher upstream than in the middle and lower reaches. In the Jinghe River, the deep groundwater aquifer received recharge from the shallow groundwater layers and from the river. At the edge of the Ebinur Lake, the interaction of groundwater and surface water was low and springs became the important recharge source for the lake. The results of this study provide insights into the determination of river hydrological processes and the management of water resources.