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There are many viewpoints about the sources of groundwater in the Badain Jaran Desert (BJD), such as precipitation and snowmelt from the Qilian Mountains (the upper reaches [UR] of the Heihe River Basin [HRB]) and precipitation from the BJD and the Yabulai Mountains. To understand the source of the groundwater of the BJD and their possible associations with nearby bodies of water, we analyzed variations of stable isotope ratios ( δD and δ18O) and the deuterium excess (d-excess) of groundwater and precipitation in the BJD, of groundwater, precipitation, river and spring water in the UR, and of groundwater and river water in the middle and lower reaches (MR and LR) of the HRB. In addition, the climatic condition under which the groundwater was formed in the BJD was also discussed. We found obvious differences in δD, δ18O, and d-excess among groundwater in the BJD, nearby water bodies and the HRB. The groundwater δD- δ18O equation for the BJD was δD = 4.509 δ18O-30.620, with a slope and intercept similar to that of nearby areas (4.856 and −29.574), indicating a strong evaporation effect in the BJD and its surrounding areas. The equation's slope of the BJD was significantly lower than those of HRB groundwater (6.634), HRB river water (6.202), precipitation in the BJD and Youqi (7.841), and the UR of the HRB (7.839). The d-excess (−17.5‰) of the BJD was significantly lower than those of nearby groundwater (−7.4‰), HRB groundwater (12.1‰), precipitation in the BJD (5.7‰) and in the UR of the HRB (15.2‰), and HRB river water (14.4‰). The spatial patterns of δ18O and d-excess values in the BJD suggest mixing and exchange of groundwater between the BJD and neighboring regions, but no hydraulic relationship between the BJD groundwater and water from more distant regions except Outer Mongolia, which is north of the BJD. Moreover, we conclude that there is little precipitation recharge to groundwater because of the obvious d-excess difference between groundwater and local precipitation, low precipitation, and high evaporation rates. The abnormally negative d-excess values in groundwater of the BJD indicate that this water was formed in the past under higher relative humidity and lower temperatures than modern values. [ABSTRACT FROM AUTHOR]

Summary: Hydrologic processes of glacier, snow, frozen soil, groundwater, surface water and precipitation have always been the common concern of hydrologists. The purpose of this study is to identify the hydrologic processes in different landscape zones, based on the isotopic and hydrochemical analysis of glacier, snow, frozen soil and groundwater. The chemical compositions were characterized by Ca–HCO3 in the glacier snow zone, Mg–Ca–SO4–HCO3 in the alpine cold desert zone, Ca–Mg–HCO3 in the marsh meadow zone, Ca–Mg–HCO3 in the alpine shrub zone, and Na–Ca–SO4 in the mountain grassland zone. The end-member mixing model was employed for hydrograph separation. The results showed that during the melting period Mafengou River water was recharged by glacier–snow melt water about 34%, thawed frozen soil water in each of the landscape zones about 12%, and groundwater about 54%. This study suggested that Mafengou River water during the melting period was mainly recharged by glacier–snow melt water, groundwater and thawed frozen soil water. [Copyright &y& Elsevier]