Analysis and modelling of seasonal nitrate concentration variations in thegroundwater of the Mnasra aquifer, Morocco

A mechanistic simulation model was developed for predicting, under field co nditions, the unsaturated water flow and nitrogen transfer in an area locat ed in Mnasra. The model parameters can be calculated from easily measured p hysical and chemical soil properties or obtained from the literature. Compa rison between observed and calculated groundwater nitrate concentrations re vealed that the application rate of 120 kg N . ha(-1).yr(-1) should be redu ced on agricultural soils, especially during winter, which coincides with h eavy rainfall and the absence of vegetation cover. (C) 1999 Academie des sc iences / Editions scientifiques et medicales Elsevier SAS.).