Parameterisation and validation of the CleanCityCover tool to assess source areas of urban diffuse pollution for case study areas in Aarhus, Denmark

Diffuse pollution from polluted urban surfaces and transported with stormwater runoff into surface waters remains a significant challenge towards achieving zero pollution from cities. Often it appears to be not clear where what kind of pollution actually originated. We therefore adopted a pollution source area approach to develop a tool named CleanCityCover, which identifies critical source areas of urban diffuse pollution. The tool was parameterised for four study areas in Aarhus for three pollution types – dry deposition, pollution due to traffic and metal roofs. The CleanCityCover is a web- based, interactive tool displaying the spatial patterns of different pollution types, summary of annual runoff quality, results of functional connectivity analysis and a pollutant ranking summary. The tool is validated for heavy metal (zinc, copper and lead) concentrations from the runoff of three of the four study areas in Aarhus. A reasonable validation was achieved at the three study areas with correlation coefficient varying from 0.57 to 0.92.