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

A simple GIS-linked model for groundwater nitrate transport has been developed in the IDRISI GIS environment. The transport model, based on advection transport only, is directly incorporated into a GIS subroutine using the Pascal computing language. This model requires less data than classical approaches and provides a user-friendly model environment. The GIS-model was tested on a 20 km(2) hydrogeologic catchment, particularly vulnerable to agricultural nitrate pollution. The model was coupled with an unsaturated zone transport model (AgriFlux), which simulates water and nitrate fluxes leaving the root zone. The results indicated that the simulated nitrate concentrations were in good agreement with measured values. In order to compare the GIS-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.