A review of groundwater vulnerability assessment to nitrate pollution in the Mediterranean region.

Abstract

The concept of groundwater vulnerability , involving the identification of areas susceptible to contamination from surface sources, plays a crucial role in decision-making for land use monitoring and groundwater management. This study evaluates vulnerability assessment methods across eight Mediterranean countries, revealing key methodological insights. In Algeria, the DRASTIC model outperformed GOD (R² up to 0.71), with modifications achieving R² = 0.829, while the PI method's incorporation of topographic and soil parameters enhanced accuracy. Moroccan studies demonstrated that integrating land use (DRASTIC-LU) significantly altered vulnerability classifications, with machine learning achieving a nitrate correlation of 0.6645. Tunisian aquifers showed strong DRASTIC performance (R² = 0.76), further improved by the Specific Vertical Vulnerability (SI) method (R² = 0.73). Italy's adapted SINTACS method reached R² = 0.47, underscoring the importance of aquifer-specific adjustments. Spain's LU-IV method, incorporating crop-specific nitrogen surpluses, proved more reliable than conventional approaches. Greece's modified DRASTIC, replacing qualitative with quantitative parameters and land use integration, boosted correlations from r = 0.293 to r = 0.696. In Turkey, SINTACS validated 95% of nitrate observations, while calibrated DRASTIC improved correlations from 0.280 to 0.485. Egyptian assessments identified 62% of areas as medium-to-high risk. Three critical findings emerge: (1) Modelcustomization consistently enhances accuracy; (2) Hybrid approachesoutperform standalone models; and (3) Regional variability necessitates context-specific adaptations. The review advocates for integrated assessments combining hydrogeological factors, anthropogenic influences, and advanced modeling to guide targeted groundwater management. These insights are urgent for the Mediterranean, where climate change and intensive land use exacerbate nitrate contamination risks.