The diagram is a derivative from the map 2.10 and is produced by summarising the single city information into country related information.
The degree of soil sealing is taken from the Pan-European imperviousness layer that contains the degree of soil sealing. To approximate the morphological area of the city the reference unit, is composed of the Urban Morphological Zones (derived from CLC 2006) inside the core city boundaries (core city defined in Urban Atlas / Urban Audit) and above a threshold of 10ha. Those reference unit objects have been overlaid onto the soil sealing mosaic of Europe to compute the mean soil sealing degree of each core city UMZ by means of zonal statistics.
