3D modelling of solute transport and mixing during managed aquifer recharge with an infiltration basin

Artificial basins are used to recharge groundwater by many municipalities improve the sustainability of storm water management. Despite its increasing operational implementation, artificial still raises numerous questions related impact on quality. In this paper, a 3D numerical model MAR basin/aquifer system was implemented in order simulate fate and pollutants. It illustrate complex distribution time space tracer contaminant injected basin. The based well instrumented infiltration basin located Chassieu (Lyon area, France). well-known Richards flow saturated unsaturated zone study site. transfer solutes modelled advection-dispersion-equation (ADE). calibrated during rain event using hydraulic head electric conductivity data from set piezometers around validated one month period operation presenting several events. then solute pollutant considered as high intensity event. This simplified test case illustrated mechanism capillary trapping vadose effect sampling point location concentration measurements. Three main results were obtained: (1) promoted retention up 20% zone, (2) 0 24% could be recovered depending piezometer location, (3) averaged decreased 50% if measuring device is lowered 5 m under table. These strongly site dependant but observed trends should while discussing punctual quality measurements monitor systems. also allowed suggest some guidelines for positioning.