Translating the agricultural N surplus hazard into groundwater pollution risk: Implications for effectiveness of mitigation measures in nitrate vulnerable zones

Abstract In the Nitrate Vulnerable Zones farmers are required to implement measures reduce nitrogen (N) surplus. Nevertheless, in some cases status of water bodies show that effect these remains insufficient despite global decrease N surpluses. The present work aims contribute with a method produces an appropriate indicator for mitigation effectiveness reducing groundwater nitrate pollution. Global Risk Index (GRI) results from overlaying agricultural surplus hazard and aquifer vulnerability. It includes both irrigation activity precipitation contribution recharge calculated at municipality level. integrates range regional datasets combined monitored (NO3?) concentrations under GIS framework. Results pollution Tagus Zone (TVZ) aquifers has been aggravating spite overall reduction surpluses resulted implementation Nitrates Directive measures. Twelve years after TVZ designation, GRI indicates high moderate NO3- risk, respectively 33 % 66 territory. Scenario analysis potential targeted ending risk areas 13 %. This supports must be reformulated spatially according site specific hazards vulnerabilities.