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

2. 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?

3. 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

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

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

6. 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?

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

8. 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

9. 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)

12. Population estimates by Urban Atlas polygon

13. 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

14. 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.

15. 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

16. Green urban areas accessible from a building block

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

20. 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

24. 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?