A GIS-linked model for the assessment of nitrate contamination in groundwater

A simple GIS-linked model for groundwater nitrate transport has been develo ped in the IDRISI GIS environment. The transport model, based on advection transport only, is directly incorporated into a GIS subroutine using the Pa scal computing language. This model requires less data than classical appro aches and provides a user-friendly model environment. The GIS-model was tes ted on a 20 km(2) hydrogeologic catchment, particularly vulnerable to agric ultural nitrate pollution. The model was coupled with an unsaturated zone t ransport model (AgriFlux), which simulates water and nitrate fluxes leaving the root zone. The results indicated that the simulated nitrate concentrat ions were in good agreement with measured values. In order to compare the G IS-linked model with a more complete model, simulations were also performed with MT3D-MODFLOW. The similarities between the results of the two models confirm the validity of the GIS-linked model. (C) 1999 Elsevier Science B.V . All rights reserved.