Application of Modified DRASTIC Method for the Assessment and Validation of Confined Aquifer Vulnerability in Areas with Diverse Quaternary Deposits

Abstract

Accurate vulnerability assessment methods are essential for effective groundwater management and protection, allowing the identification of areas vulnerable to pollution. The widely used DRASTIC method has been modified to improve groundwater vulnerability assessment in regions where Quaternary sediments form a confining layer above the main useful aquifer. This study applied the modified DRASTIC method to two study areas in Estonia with heterogenous Quaternary sediments. The results were compared to the original DRASTIC method and a groundwater vulnerability assessment method used formerly in Estonia. The results significantly improved with the modified version compared to the original method. The modified method also exhibited stronger correlations with nitrate concentration data, illustrating the higher accuracy of the modified DRASTIC method in vulnerability assessment in regions with confined aquifers. The results highlight the significance of modifying the vulnerability assessment methods according to regional geological conditions to evaluate groundwater vulnerability accurately and support informed decision-making in groundwater management and protection.