Application of Specific Groundwater Vulnerabilities Methodologies to Point Sources Pollution: A Review

Assessing the groundwater vulnerability to point source pollution is a very contentious subject amongst researchers. This is because many methods for assessing groundwater vulnerability to pollution have been modified and adapted to suit various contexts of study investigations and conditions. This paper provides an overview of numerous intrinsic groundwater vulnerability methods and how they were modified to improve their specificity, efficiency, and effectiveness from previous studies across different parts of the world. Depending on the context, groundwater vulnerability assessment techniques utilise a range of complex biological, chemical, and physical processes such as in Analogical Relation (AR) and Numerical Model Assessment methods to simple weight-based criterion as in most common parametric methods such as the AVI, DRASTIC, and the GOD method. Each of these vulnerability assessment methods have their strengths and limitations which were reviewed in this paper. Most groundwater vulnerability methods are based on selecting between objective and subjective criterion for assessing the risk of groundwater contamination and their modification to target specific contaminants comes with a huge risk of bias. This paper also highlights the importance of why the validation of groundwater vulnerability assessment methods is critical in affirming the outcomes from groundwater assessment methods.