Assessment of Groundwater Contamination Vulnerability Using a Fuzzy Technique on the GIS Platform: A Case Study of Miryang City, Korea

This study aims to improve the Original DRASTIC Model (ODM) for the assessment of groundwater contamination vulnerability. Original DRASTIC method uses 7 parameters such as Depth to water, Net Recharge, Aquifer media, Soil media, Topography, Impact of vadose zone and Hydraulic Conductivity. Advanced DRASTIC Model (ADM) was developed adding two more DRASTIC factors of lineament density and landuse to ODM. The fuzzy logic was applied to ODM and ADM to improve their ability in evaluating the groundwater contamination vulnerability. Miryang City of Korea was selected for the study area to accomplish the research purpose because the city had two functions of urban and rural features. Thematic maps for 7 and 9 layers of ODM and ADM were compared to those of the fuzzy model (FDM), and fuzzy thematic maps showed more superior delineation. Although the vulnerability map of ADM was a little simpler than that of ODM, it increased the area of the low vulnerability sector. The superiority of ODM, ADM and FDM was evaluated by NO₃-N concentrations and electrical conductivity (EC) of groundwater in the study area. The correlation coefficients between ODM, ADM and FDM Indices, and NO₃-N concentrations and EC values were calculated, and ADM had larger values than ODM. ADM using fuzzy logic (FDM) rendered the largest coefficient values. It was concluded that fuzzy ADM (FDM) made the best detailed groundwater vulnerability map with the significant statistical results.