Temporal evolution of age data under transient pumping conditions

摘要: While most age data derived from tracers have been analyzed in steady-state flow conditions, we determine their temporal evolution when starting a pumping. Our study is based on model made up of shallowly dipping aquifer overlain by less permeable aquitard characteristic the crystalline Plœmeur (Brittany, France). Under pseudo transient assumption (instantaneous shift between two fields), solve transport equation with backward particle-tracking method and concentrations at pumping well CFC-11, CFC-12, CFC-113 SF6. Apparent ages evolve because modifications pattern non-linear tracer atmospheric concentrations. To identify respective role these causes, propose successive analyses. We first convolute residence time distributions initially arising different times same sampling time. secondly one distribution various times. show that control apparent year modified piston-like to much broader distribution. In year, contains information can be used better constrain hydrogeological systems slightly compensate for small number tracers. Later, hardly evolves only this phase, time-series do not reflect any pattern.