Groundwater Quality Assessment and Refining Vulnerability Index through Machine Learning and Pollution Index Integration: A Case Study of the Koohpayeh Plain in Central Iran.
- Department of Civil Engineering, Lecturer of Water Science Engineering, Khomeynishahr Branch, , Islamic Azad University, Esfahan, Iran
- Department of Civil Engineering, Faculty of Civil Engineering, Khomeynishahr Branch, , Islamic Azad University, Esfahan, Iran
Received: 2025-05-13
Revised: 2025-05-24
Accepted: 2025-06-14
Published in Issue 2025-07-01
Copyright (c) 2025 Navideh Najafpour, Shahrokh Soltaninia (Author)

This work is licensed under a Creative Commons Attribution 4.0 International License.
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Abstract
Groundwater contamination is a critical issue, especially in arid regions where it serves as the main water supply. This study emphasizes the importance of integrating traditional methods with machine learning techniques to enhance groundwater vulnerability assessments in the Koohpayeh aquifer, central Iran. Groundwater quality was assessed using the Pollution Index of Groundwater (PIG) and Water Quality Index (WQI). WQI values ranged from less than 15 to 55, indicating poor water quality, particularly in central and southeastern regions, due to contaminants from agriculture and urban activities. The PIG index revealed severe pollution in 45% of the area, showing a strong correlation between high PIG and low WQI values. Machine learning methods, including Random Forest (RF), Gradient Boosting (GB), and Support Vector Regression (SVR), were used to refine the DRASTIC model. RF emerged as the most effective model, achieving an MSE of 0.05 and an R² of 0.89, outperforming GB, which had a slightly higher R² of 0.91 but a greater MSE of 0.08. A strong correlation between nitrate levels and the optimized vulnerability indices validated the improved DRASTIC model’s accuracy. The enhanced DRASTIC model provides a more reliable tool for identifying high-risk areas and developing targeted groundwater management strategies. This study underscores the value of combining traditional assessments with machine learning to improve groundwater quality monitoring and protect public health. These findings can support decision-makers in prioritizing pollution control strategies, optimizing groundwater monitoring programs, and designing sustainable management plans in vulnerable arid and semi-arid regions.
Keywords
- Water resource,
- Data-driven approach,
- ; Modified DRASTIC,
- Spatial analysis,
- Water quality index
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