An Improved Craig–Gordon Isotopic Model: Accounting for Transpiration Effects on the Isotopic Composition of Residual Water during Evapotranspiration

Evapotranspiration (ET) is a crucial process in the terrestrial water cycle, and understanding its stable isotopic evolution essential for comprehending hydrological processes. The Craig–Gordon (C-G) model widely used to describe fractionation during pure evaporation. However, natural environments, ET involves both transpiration (T) evaporation (E), traditional C-G does not account effect of on fractionation. To address this gap, we propose evapotranspiration-unified (ET-UCG) model, which extends by incorporating transpiration’s isotopes. We verified validity ET-UCG comparing simulation results with model’s discrete special scenario that simulated residual after daily consumption. Further, two different scenarios using investigate water’s composition. Our numerical experiments show indirectly affects degree isotope reducing true ratio, even though it directly produce Therefore, composition estimated consistently lighter than ET. Despite T/ET conditions, follows same line. These highlight importance considering effects when provide valuable insights into processes potential applications field.