Developing a global, peoplebased definition of cities and settlements

Transcription

1 Developing a global, peoplebased definition of cities and settlements By Lewis Dijkstra, Lewis.Dijkstra@ec.europa.eu Head of the Economic Analysis Sector DG for Regional and Urban Policy, Regional & Urban Policy

2 SDG City goals, but no city definition City Centre Edge of the city Open Space Low High Air pollution High Low Access to transport High Low Built-up area per head Low High Population change Low (neg) High Built-up change Low High

3 Access to public transport by distance to centre % of population Praha Berlin London Madrid Paris km from city centre

4 The well known narrative The world is 50% urban. Middle income countries are less urbanised. Low income countries are least urbanised. Urbanisation will grow rapidly in low-income countries between 2010 and is purely based on national definitions

5 But national definitions are fine I know it when I see it (USA Sup. Court) Differences between national definitions must be quite small. A city is a relative concept and differs between cultures and countries. But do we see the same things? Can this be verified without a global definition? Do economies of transport, scale and agglomeration require more people in some countries?

6 A single density threshold cannot reproduce the nationally defined urban population shares

7 National definitions vary and are often not statistical 75 countries use population size or density, but thresholds and spatial units vary 47 use a combination of population and other indicators 10 use other indicators than population 100 countries use administrative designations, not a statistical definition that can be replicated in other countries

8 Around half the national definitions rely on population size (and density)

9 Number of countries 85 countries out of 103 use a minimum population of 5,000 or less 35 Minimum population size for urban areas, WUP Residents

10 14 countries use density Country Minimum density Germany 150 Cambodia 200 USA 390 and 195 Canada 400 India 400 Bhutan 1,000 Philippines 1,000 China 1,500 Six other countries did not report the density threshold Density is highly dependent on the size of the spatial unit

11 Share of global population, 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% <10 Population living below a density threshold by size of grid cells, 2015 <50 <100 <200 <300 <500 <1,000 <1,500 <2,000 <3,000 <4,000 <5,000 <6,000 <7,000 Population density thresholds in inhabitants per sq km <8,000 Total Size of grid cell in sq km 1,000, ,000 90,000 40,000 10,000 2, /4

12 What indicators can be used globally Agricultural employment? Varies too much Infrastructure? No harmonised data Services? No harmonised data Poverty? Circular argument Rural cannot be defined by problems, because then no problems = no rural Remoteness Separate dimension

13 Access to cities - Remoteness

14 Two definitions joined by cities Degree of urbanisation Towns & suburbs Rural areas Cities Functional Urban Area Commuting zones Non-metro areas

15 Two different concepts of urban Population in nationally defined urban areas and by degree of urbanisation, 2015 Share of population, in % Northern Africa Middle Africa Eastern Africa Western Africa Southern Africa Eastern Asia Western Asia Central Asia South-Eastern Asia Southern Asia Northern America Central America Caribbean South America Northern Europe Western Europe Eastern Europe Southern Europe Oceania World Rural areas Towns & suburbs Cities ND Urban area

16 Urban areas lost in translation? Small urban areas Medium density Medium population Medium share of agricultural jobs Some services (primary school, doctor) Large urban areas High Density Big population Low shares of agricultural jobs Specialised services (higher education, hospital, government) Europe & Americas Africa & Asia

17 National definition more urban (green) Degree of urbanisation more urban (red)

18 More agreement on large cities 60 Population in nationally defined cities over 300,000 and urban centres, Northern Africa Middle Africa Eastern Africa Western Africa Southern Africa Eastern Asia Western Asia Central Asia South-Eastern Asia Southern Asia Northern America Central America Caribbean South America Northern Europe Western Europe Eastern Europe Southern Europe Share of population, in % Oceania World Urban centers between 50,000 and 300,000 Urban centres over 300,000 ND cities

19 77% (98%) of nationally defined cities match an urban centre of 300,000+ (all urban centres) 100 Cities (national definition) compared to urban centres Share of the number of cities, in % Northern Africa Middle Africa Eastern Africa Western Africa Southern Africa Eastern Asia Western Asia South-Eastern Asia South-Central Asia Northern America Central America Caribbean South America Northern Europe Western Europe No Match Urban centre <300K Urban centre >300K Eastern Europe Southern Europe Australia/New Zealand World

20 90% (99%) of the population of nationally defined cities matches an urban centre of 300,000+ (all UCs) 100 Cities (national definition) compared to urban centres Share of the city population, in % Northern Africa Middle Africa Eastern Africa Western Africa Southern Africa Eastern Asia Western Asia South-Eastern Asia South-Central Asia Northern America Central America Caribbean South America Northern Europe Western Europe No Match Urban centre <300K Urban centre >300K Eastern Europe Southern Europe Australia/New Zealand World

21 580 (35%) urban centres of 300k+ do not match a nationally defined city Share of tthe total number urban centres, in % Northern Africa Middle Africa Eastern Africa Western Africa Urban centres of more than 300,000 that match a nationally defined city Southern Africa Eastern Asia Western Asia Central Asia South-eastern Asia Southern Asia Northern America Central America Caribbean South America Northern Europe Western Europe Eastern Europe Southern Europe Oceania World No match Matches with 2 or more ND cities Matches with one ND city

22 12% of the population of urban centres of 300k+ is not in a city Population in urban centres of more than 300,000 that match a nationally defined city Share of total population in an urban centre, in % Northern Africa Middle Africa Eastern Africa Western Africa Southern Africa Eastern Asia Western Asia Central Asia South-eastern Asia Southern Asia Northern America Central America Caribbean South America Northern Europe Western Europe Eastern Europe Southern Europe Oceania World No match Matches with 2 or more ND cities Matches with one ND city

23 Pilot projects to compare definitions Apply the definitions also to administrative units (census tracts, municipalities ) Appraise the result: Too urban or too rural? Too many or too few cities? Improve data (better population and/or remote sensing data) Find out if/how we can improve the definitions

24 Pilot projects by EC, OECD and WB Australia Brazil (completed) Colombia Egypt Haiti Indonesia India Jordan Malaysia Mozambique Pakistan South Africa (completed) Tunisia Turkey Uganda Ukraine USA

25 Australian cities R² = 0,

26 Colombian cities R² = 0,

27 Brazil We believe that this method offers a useful basis for statistical comparisons across national borders... useful for generating Sustainable Development Goals indicators, producing data for these three types of cluster or for individual municipalities

28 Survey by UN Statistical Division 1. Algeria 2. Argentina 3. Australia 4. Bolivia 5. China 6. Cuba 7. Ecuador 8. Ethiopia 9. Indonesia 10.Japan 11.Mexico 12.Mongolia 13.Namibia 14.New Zealand 15.Republic of Korea 16.Senegal 17.Thailand 18.USA 19.Venezuela 20.Zambia

29 Responses to the UN survey 9 out of 12 NSIs: it captured their main cities. 5 out of 8 NSIs the validity was good or satisfactory (1 poor and 2 unacceptable) 9 out of 10 NSIs could produce data by degree of urbanisation 9 out of 13 NSIs useful for international comparisons 11 out of 12 NSIs useful for measuring the SDGs 5 NSIs did not reply Some confusion about density thresholds and the distinction between cities and towns

30 Driving time buffers Commuting data is not widely available We will create a driving time buffer around each urban centre. Distance will depend on the population size of the city, GDP per head of the country and the road network Time series in selected countries

31 Timeline Launched at the Habitat III conference in 2016 Side event UN Statistical Commission 2017 as part of the UN GGIM meeting 2018 an event dedicated to this topic Plenary Meeting of the UN Statistical Commission 2019: for information 2020: for discussion and decision

32 More information l-city-and-settlement-definition_en