Interaction between intermittent river and groundwater in arid and semiarid basin considering the influence of evaporation on isotopic compositions

Study region: Tabu Basin is located on a typical-deserted steppe in Inner Mongolia, China and plays a significant role in maintaining ecological stability of northern China.

Study focus: Among rivers worldwide, 51–60 % cease to flow for at least one day annually, especially in arid and semiarid areas. Understanding interactions between intermittent rivers (IRs) and groundwater (GW) is crucial for protecting water resources and sustaining ecological balance. A comprehensive framework was developed to analyze these interactions.

New hydrological insights for the region: Unlike previous studies, this study considered seasonal differences in hydrochemical and isotopic compositions of IR and GW, as well as the intensive influence of evaporation. Multitemporal datasets were employed to analyze the IR–GW interaction across spatial, temporal, and profiling scales. Hydrochemical evidence and isotopic analysis indicated the input of meltwater with depleted isotopic signatures to GW and GW recharge to IR. The isotopic compositions followed the order of rainfall < GW <IR; the higher isotopic compositions of the IR were mainly attributed to evaporation. A formula for minimizing the influence of evaporation was derived based on Rayleigh fractionation. Using the MixSIAR model, the GW and rainfall contributions to the IR were 63.8 % and 36.2 %, respectively. The GW was consisted of 55.3 % meltwater and 44.7 % summer rainfall. The integration of multiple methods offers an effective approach for studying IR–GW interactions in arid and semiarid areas.