A lumped parameter model to evaluate the relevance of excess air as a tracer of exchanged flows between transmissive and capacitive compartments of karst systems

The objective of this study was to evaluate the relevance using excess air (EA) for characterization drain/matrix exchange in karst systems a rainfall discharge model coupled with simulation EA measured at outlet studied system. conceptual assumes linear relationship between formation and increase hydrostatic pressure capacitive part aquifer. simulated spring consists mixing water circulating different compartments aquifer, their own signature. analysis is performed taking as an example Durzon system (Larzac, France). modeling applied daily time series 18 measurements main within 3 hydrological cycles. results show that variations can be explained by recharge processes conduit matrix. thus contain valuable information about flow dynamics Furthermore, use measurements, despite sparse temporal resolution, allows reducing uncertainties estimation some parameters reservoir used discharge.