Protection from natural and anthropogenic sources: a new rating methodology to delineate "Nitrate Vulnerable Zones"

In the last years, because of uncontrolled human activities, a significant increase of groundwater pollution occurred worldwide, with nitrate being among the most widespread pollutants. The assessment of groundwater vulnerability represents an important tool for developing groundwater quality plans and in the delimitation of Nitrate Vulnerable Zones. In this study, three rating methods (DRASTIC, SINTACS and GOD) were applied in an alluvial plain to check the reliability of the results comparing the obtained thematic maps with the observed nitrate concentrations in groundwater. Results show that without large modifications for specific vulnerability, these methodologies cannot describe the actual groundwater nitrate distribution in the study area. A new easy methodology called Protection from Natural and Anthropogenic sources (PNA) was then defined and tested. The PNA map divides the study area in five classes of vulnerability from very low to very high and shows a fair correlation with groundwater nitrate concentrations. The selection of the parameters and of the algorithm makes PNA strongly flexible and applicable in similar watersheds around the world, as a tool for the delineation of Nitrate Vulnerable Zones.