Tracer-aided hydrological model in large mountainous catchments

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 hydrological models that integrate the transportation and fractionation processes of water stable isotope are increasingly used to constrain parameter uncertainty and refine the parameterizations of specific hydrological processes in cold regions. However, the common unavailability of site sampling of spatially distributed precipitation isotopes hampers the practical applications of tracer-aided models in large-scale catchments. We explored the utility of precipitation isotope data derived from the isotopic general circulation models (iGCMs) in driving tracer-aided hydrological models in the typical large basins on the Tibetan Plateau (TP). Results indicate that the model driven by iGCM data can simulate the variation of isotope composition in stream water well. Integrating isotope simulation into the hydrological model helps reduce the modeling uncertainty, improve the parameter identifiability, and improve the quantification of the contributions of runoff components to streamflow.