For planning GQMN, this study applied a GIS model to calculate the CRI by overlaying the
hazard map and vulnerability map. Higher CRI suggested higher probability and risk of
contamination occurrence. Nantou area of Taiwan was chosen as the study area. The hazard
map in the case study meant the land use and population density, and the vulnerability map
included the soil type and topography. The selection of hazard or vulnerability map is not
limited to those used in this study, as long as the intrinsic characteristics of the natural aquifer
environment and extrinsic behavior of contamination resulting from human activities are both
taken into account