EFFECTS OF TOPOGRAPHY ON THE TRANSPORT OF AGRICULTURAL CHEMICALS TO GROUNDWATER IN A SAND-PLAIN SETTING

Location and description of an experimental field during growing seasons in a sandy alluvial basin. Two multiport wells are detailed on sites. Method of investigation with succion lysimeters and wick samplers. Concentrations of nitrate nitrogen, chloride , sulfate , atrazine plus metabolites are examinated on 5 years in unsaturated soils on upland and downland sites. Estimation of chemical mass transported in groundwater. Estimated flux of agricultural chemical to the water table is proposed. Comparison of the two sites results and discussion.