A New Method for Groundwater Vulnerability and Risk Mapping Using GIS and Numerical Modeling

The assessment of groundwater vulnerability to pollution has become an important element for proper water resource management and land use planning. The available methods do not evaluate the regional risk within the perspective of the well capture zone and hence fail to predict the implications that high vulnerability areas have on the water quality of abstraction wells. This study presents a methodology to search for areas within the well capture zones with the highest risk indices. This includes the use of DRASTIC methodology for vulnerability mapping and numerical modeling¡ using MODFLOW and MODPATH¡ for capture zone delineation. The integration of these elements¡ performed in a GIS environment¡ provided the mechanism to assess risk mapping and identify areas within the capture zone in Firouze county in Razavi Khorasan Province in Iran that must be prioritized in terms of groundwater monitoring and use restriction.