GIS-based DRASTIC method for groundwater vulnerability assessment: a review

Groundwater vulnerability is a burning issue all over the world due to the deterioration of groundwater level and increasing contamination which poses serious detrimental risk to the environment. To identify this risk, extensive research has been carried out to assess the groundwater vulnerability by using different methods. Generally, the process-based method, statistical method, and overlay & index methods are used in this regard. DRASTIC method is one type of overlay & index method for vulnerability assessment. This paper represents a comprehensive review of available literature on the applications of Geographic Information System (GIS)-based DRASTIC method for groundwater vulnerability assessment. Also, some other types of overlay & index methods are compared with the DRASTIC method. This study discusses the rescaling of rating ranges and modification of DRASTIC parameters, and shows the comparison of DRASTIC method with other vulnerability assessment methods. In addition, this study identifies some research gaps on the present state of groundwater vulnerability assessment and proposes some research needs for further studies. The findings of this study indicate that the combination of GIS and DRASTIC are more viable for groundwater vulnerability assessment. Furthermore, modified DRASTIC method can be used for agricultural, arid, semi-arid, and basaltic regions.