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Abstract:
Karst aquifers are characterized by complex heterogeneous and anisotropic hydrogeological conditions which are very different to most other geological formations. The recharge behaviour of depends on critical zone architecture and meteorological conditions in karst area. In this work, a conceptual tracer-aided model was developed to assess the recharge behaviour of karst aquifer, by implementing staple isotope and age tracking in the lumped VarKarst model. Spring discharge and isotope composition results are jointly considered in calibration routine, to confine the uncertainty of water budget estimated by the independent hydrological model. The tracking results of isotope confirms subsurface hydraulic connections and transport dynamics, which reveals the variations in infiltration paths under different wetness. Unlike other methodologies that assess the contribution of the allogenic and autogenic components to the total recharge of karst aquifer, the water components with different age in recharge (e.g. event water and pre-event water or new water and old water) can be identified according to the age dynamic of infiltration tracked by the tracer-aided model. Thanks to the statistical distribution functions, the tracer-aided model can highlight the influences of soil and epikarst depths on recharge behaviour, although it is a lumped model. We conclude by emphasizing that the integration of hydrological estimation and isotope and age tracking have a significant advance in enhancing knowledge of the recharge behavior in carbonate aquifer, allowing a more realistic and robust conceptual model to be developed.
