Spatial variation characteristics of hydrogen and oxygen isotopes in groundwater of arid inland basin: A Case Study of Sugan Lake Basin

Sugan Lake Basin is a typical salinized wetland ecosystem in China's arid inland basins, so exploring the formation and evolution mechanism of groundwater is of vital importance for the protection of the wetland ecosystem in the study area. Based on the stable isotope compositions of hydrogen and oxygen (δ²H, δ¹⁸O) and d-excess in the groundwater of Sugan Lake Basin, the authors adopted correlation analysis and spatial interpolation method to analyze the compositions characteristics of oxygen and hydrogen isotope of groundwater and identify the main recharge sources of groundwater. The spatial variations of stable isotope in groundwater were also decomposed and regional hydrological cycle processes were revealed. The results were concleded as follows: ① The atmospheric precipitation in the high-altitude mountainous areas surrounding the study area served as the primary recharge source for groundwater in Sugan Lake Basin. ② The values of δ²H, δ¹⁸O and d of groundwater were -105.87‰ to 14.61‰, -13.93‰ to -0.17‰ and -2.62‰ to 18.1‰, respectively. Spatially, δ²H and δ¹⁸O show the enrichment characteristics in the southeast and depletion in the northwest, while d had the feature of being higher in the east and lower in the west. ③ The spatial distribution characteristics of hydrogen isotopes of groundwater were affected by the sources of recharge, mixing and evaporation. ④ Groundwater in the eastern part of the study area was mainly recharged by the mountain groundwater lateral runoff and river water seepage, while the groundwater in the northwestern part was mainly recharged by the mountain groundwater lateral runoff. The results could provide important scientific support for the sustainable management of water resources and ecological environment protection in this area.