Modification of the DRASTIC Framework for Mapping Groundwater Vulnerability Zones

Area of Science:

• Environmental Science
• Hydrogeology
• Water Resource Management

Background:

• Groundwater vulnerability assessment is crucial for water resource protection.
• The DRASTIC technique is widely used but has limitations in parameter rating and weighting.
• Nitrate (NO3) contamination is a significant threat to groundwater quality.

Purpose of the Study:

• To compare different methods for calibrating the DRASTIC framework using nitrate concentrations.
• To develop improved groundwater vulnerability maps for the Meshqin-Shahr plain, Iran.
• To evaluate the effectiveness of modified DRASTIC parameters and weights.

Main Methods:

• Collected 22 groundwater samples to measure nitrate (NO3) concentrations.
• Applied linear (Wilcoxon test, statistical) and nonlinear (Genetic Algorithm [GA]) modifications to DRASTIC.
• Developed groundwater vulnerability maps using calibrated DRASTIC frameworks.

Main Results:

• Modified DRASTIC frameworks showed improved performance over the unmodified version.
• The Wilcoxon-GA-DRASTIC method achieved the highest accuracy (R² = 0.78) in predicting nitrate concentrations.
• Modification of parameter ratings was more effective than modifying weights alone.
• Simultaneous modification of ratings and weights yielded the best results.

Conclusions:

• Calibrating the DRASTIC technique with nitrate data significantly enhances groundwater vulnerability assessment.
• The Wilcoxon-GA-DRASTIC approach offers a robust and accurate method for groundwater vulnerability mapping.
• Optimizing DRASTIC parameter ratings and weights is essential for reliable groundwater protection strategies.