Can we use precipitation isotope outputs of isotopic general circulation models to improve hydrological modeling in large mountainous catchments on the Tibetan Plateau?

Abstract. Issues related to large uncertainty and parameter equifinality have posed big challenges for hydrological modeling in cold regions where runoff generation processes are particularly complicated. Tracer-aided models that integrate the transportation fractionation of water stable isotope increasingly used constrain refine parameterizations specific regions. However, common unavailability site sampling spatially distributed precipitation isotopes hampers practical applications tracer-aided large-scale catchments. This study, taking data (isotopes-incorporated global spectral model – isoGSM) derived from isotopic general circulation (iGCMs) as an example, explored its utility driving a Yarlung Tsangpo River basin (YTR; around 2×105 km2, with mean elevation 4875 m) on Tibetan Plateau (TP). The isoGSM product was firstly corrected based biases between gridded estimates limited measurements. Model simulations driven by were then compared those forced interpolated Our results indicated (1) spatial helped reduce improve identifiability mountainous catchment TP, calibration method using discharge snow cover area fraction without any information isotopes; (2) parameters estimated presented higher transferability nested subbasins produced performance validation period than measurements; (3) successfully rejected sets overestimated glacier melt contribution gave more reliable contributions components, indicating served better choice provide informative measurements at macro scale. work suggested plausible combining measurements, even sparse network, improving high mountain basins.