The 2-year measurements of δ2
H and δ18
O in rainfall, stream, soil, and groundwater revealed that surface and groundwater are isotopically disconnected from the annual precipitation cycle but showed bidirectional interactions in the Schwingbach catchment. We established a hydrological model to estimate spatially distributed groundwater ages and flow directions. Our model revealed complex age dynamics and showed that runoff must have been stored in the catchment for much longer than event water.