Abstract: Groundwater nitrate pollution, as a global problem, is not only an environmental issue but also an economic and human health problem. The DRASTIC method can provide groundwater vulnerability to pollution but does not contain risk concept and ignore hazard’s dynamic nature of water movement. The obtained results may baffle the implementation of the EU Water Framework Directive in groundwater quality management field. We developed a dynamic risk assessment method based on DRASTIC and applied it in a watershed of the Upper Bann Catchments, Northern Ireland, for the purpose of groundwater nitrate pollution risk assessment. The framework will support decision makers efficiently and effectively carry out groundwater diffuse pollution prevention practices at watershed scale. “Very high” and “high” ranked areas for groundwater nitrate pollution occupy 51% and 105% of the study area respectively. The results are helpful for local government’s policies making by focusing on “very high” and “high” groundwater pollution risk zones in a watershed. The dynamic risk assessment method is applicable for any soluble groundwater pollutants from diffuse sources.

Key words: groundwater pollution, risk assessment, DRASTIC, vulnerability, diffuse pollution, GIS