Green urban areas Assessing the proximity of green areas for the population of major cities By Hugo Poelman – Veerle Martens

Research questions What is the distribution of green urban areas in major cities? How does their distribution relate to the population distribution? How to summarise detailed information within cities to produce city-wide indicators?

Basic data sources Data sources need to inform about: Definition and extent of the cities Presence of green urban areas Land use categories in cities Distribution of population Street network

Definition of cities Cities and Larger Urban Zones, as defined in the Urban Audit (before the revision in 2011-2012), for which Urban Atlas data are available Methodology tested on a small set of major cities

Land use in urban areas GMES Urban Atlas Land cover/land use data (reference year 2006 +- 1 year) for 305 Larger Urban Zones Green urban areas = class 1.4.1 (+ class 3 forests) Residential urban areas are classified according to the density of soil sealing

Population distribution Detailed population distribution inside the city Register-based (bottom-up) population grids Boundaries of census tracts + related population Alternatively: top-down disaggregated population grid?

Street network Comprehensive road network in urban areas Compatible with Urban Atlas polygons Containing attribute information on accessibility for pedestrians

Methodology Map population distribution on Urban Atlas areas Identify location and surface of green urban areas Determine accessibility zones for pedestrians, starting from inhabited Urban Atlas areas Quantify the availability of green areas which can be reached within the accessibility zones Summarise the proximity indicator at city level

Population by Urban Atlas area We disaggregate population figures available at the level of raster cells or census tracts Method inspired by Klaus Steinnocher (ÖIT) Population is distributed by Urban Atlas polygons, proportionally to weighted surfaces For residential areas: weight = average % soil sealing (corrected figures used for the production of the Urban Atlas) Non-residential areas which could contain population: weight between 0.1 and 1% Other land use classes are masked (non-inhabited)

Population estimates by Urban Atlas polygon

Green urban areas Urban Atlas class 1.4.1 + forests (class 3) Bigger parks are often split by paths, but should be considered as one entity Assemble the bigger parks by “deleting” the intersecting paths Calculate the total surface of each green urban area

Accessibility zones for populated areas Selection on the street network: omitting the roads without pedestrian access Around each inhabited Urban Atlas polygon, an accessibility area is calculated, using the street network, and corresponding to 15 minutes of walking time.

Available green urban areas For each inhabited Urban Atlas polygon, we sum the surface of the green urban areas which can be reached within 15 minutes of walking Total surface of available green areas becomes an attribute of the Urban Atlas polygons City average: population-weighted average available surface within 15 minutes walking time

Green urban areas accessible from a building block

Copenhagen Relationship between available green areas and population distribution Height = population density

Summary results for selected Urban Audit cities/kernels * Average surface of green urban areas, close to population Vienna 1,895,197 m² Brussels 929,494 m² Copenhagen (kernel) 725,933 m² Stockholm (city) 485,457 m² Stockholm (kernel) 793,538 m² London 612,699 m² * Urban Audit city/kernel definitions 2004

Some conclusions Method requires reliable, detailed population distribution Some other Urban Atlas classes, in addition to green urban areas or forests, could be taken into account City averages depend on administrative boundaries: test alternative, more neutral aggregates, like high-density clusters?