The Global Centre for Risk and Innovation (GCRI)
Cities grow outward and upward, and the land they grow onto decides much of their future risk, cost and emissions. Expansion onto floodplains, steep slopes and coasts locks in exposure for generations, while sprawl raises the cost of services and travel. This page sets out how urban growth happens, how it is measured consistently across countries, and what evidence serves the planners and governments who shape it.
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NASA GIBS / EOSDIS · ASTER GDEM (METI, NASA) · Blue Marble (NASA) · © OpenStreetMap contributors (ODbL) · Natural Earth
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For urban growth and land, in GCRI's spatial-intelligence reading, the map opens on population density, night lights and true-colour imagery with relief in 3D, framed on India; 3 further NASA layers wait in the list.Satellite and model products as NASA publishes them, each with its own date; indicators, not assessments of any place; claim ceiling INTEGRATED.
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Urban expansion is the growth of a city's built-up area outward and upward as population and income rise. The land it reaches decides much of the city's future risk, cost and emissions, because floodplains and slopes are cheap and urban form lasts for centuries. Satellite data and the Degree of Urbanisation measure it consistently.
The working screen behind this subject: its structure, terms and states. Names are placeholders and values illustrative.
Urban growth and land · Riverside ward · Flood 1-in-100 overlay
flood scenario on asset register
RiverFlood extentExposed asset
| H-01 | Clinic | 0.3 |
| S-07 | School | 0.5 |
| E-03 | Substation | 1.4 |
| W-02 | Pump station | 1.3 |
| Raise substation E-03 | 1 | Medium | Service continuity | Design |
| Retention park upstream | 13 | High | Heat, recreation | Feasibility |
| Flood-proof clinic H-01 | 1 | Low | Health access | Funded |
Settlement expansion and land use. The dossier below sets out how the risk develops, what is measured, where the data come from, how it is modelled and who decides.
Population and income growth drive demand for land faster than plans, infrastructure and titling can follow. Growth then happens first and services arrive later, if at all.
Floodplains, wetlands and unstable slopes are left vacant because they are risky, which makes them affordable. Settlement there converts hazard into risk.
Compact growth reduces travel and service costs per person but concentrates exposure. Sprawl spreads exposure and raises infrastructure cost. Both need planning for hazards.
Street patterns, plot sizes and trunk infrastructure, once built, are very hard to change. Decisions taken during rapid growth fix risk and efficiency for the long term.
Each term as this page uses it. Where a standard-setting body defines the term, the wording follows that body.
| Term | Definition |
|---|---|
| Urban sprawl | Low-density, dispersed urban expansion that raises travel distances and infrastructure costs. |
| Land consumption rate | The rate at which land is converted to built-up uses, compared with population growth in SDG 11.3.1. |
| Built-up area | Land covered by buildings and other constructed surfaces, mapped from imagery. |
Each indicator carries its unit, its cadence, the kind of source behind it and the evidence label a value would carry. No values are shown: a programme supplies them under its own authority.
| Indicator | Unit | Cadence | Source type | Label |
|---|---|---|---|---|
| Ratio of land consumption rate to population growth rate | ratio | per assessment period | SDG indicator 11.3.1 methods | ESTIMATED |
| Built-up area | square kilometres | per epoch | Satellite built-up area products | OBSERVED |
| Urban population density | people per square kilometre of built-up area | per census | Population grids and built-up area | ESTIMATED |
| New built-up area in hazard zones | hectares | per epoch | Built-up area overlaid on hazard maps | ESTIMATED |
| Population by degree of urbanisation class | people | per census | Degree of Urbanisation classification | OFFICIAL |
| Land with approved plans before development | percent of new built-up area | per assessment | Planning records | REPORTED |
The topic as a computational graph: named sources feed the methods, an evidence review gates the outputs, and the decisions stay with the authorities that hold them.
Fig. 02Nodes carry their type, two metric rows and a state; connectors show what feeds what; dashed frames name the owners; the timeline is the cadence. Design of the pipeline, not a record of a run.
Named public datasets and institutional records, each with its licence class. Sources by agreement are used only under their terms and never republished.
| Source | What it gives | Licence class |
|---|---|---|
| Global Human Settlement Layer (European Commission JRC) | Built-up area, population and settlement classes over several epochs | Open, CC BY 4.0 |
| UN DESA World Urbanization Prospects | Urban and city population estimates and projections | Open, CC BY 3.0 IGO |
| UN-Habitat Urban Indicators Database | SDG 11 indicator data for cities and countries | Public, UN-Habitat terms (to check) |
| ESA WorldCover | Global land cover at ten-metre resolution | Open, CC BY 4.0 |
| Atlas of Urban Expansion (NYU Marron Institute) | Expansion, density and layout for a global sample of cities | Licence to check |
Cities and Built Environment prepares evidence. The decisions below are taken by the authorities named, under their own rules, and never by the platform.
| Who decides | The question | Evidence this page serves |
|---|---|---|
| City and regional planning authorities | Where to direct growth and which land to protect | Expansion and hazard overlays; plan coverage |
| National ministries of urban development | How to support planned expansion and trunk infrastructure | Growth projections; density profiles |
| National statistics offices | How to classify urban and rural areas consistently | Degree of Urbanisation results |
Which areas are being built on, how fast, at what density and with what access to services.
How much farmland, wetland, forest and floodplain is lost to development and what functions disappear with it.
How plans, markets, customary tenure and informal occupation interact.
How density and pattern affect the cost of roads, pipes, transport and emergency services.
Urban land often expands faster than urban population, so average densities fall and the fringe sprawls. Low-density growth raises the per-person cost of infrastructure and makes public transport harder to sustain. Very high density without services creates its own risks, from fire spread to overcrowding.
Land markets push growth towards cheaper land, which is often cheaper because it is hazardous or unserviced. Where planning is weak or slow, settlement precedes infrastructure, and retrofitting services later is costly and disruptive.
Land conversion removes natural functions. Wetlands and floodplains store water; vegetation cools; soils absorb rainfall. Sealing them raises flood peaks and heat downstream and nearby.
| Method or data | What it shows | Its limit |
|---|---|---|
| Satellite land-cover series | Built-up expansion over time | Classification errors at the urban edge |
| Cadastre and planning records | Legal land use and tenure | Incomplete where tenure is informal or customary |
| Hazard overlays | Growth in exposed zones | Hazard maps can be outdated or coarse |
| Density and service models | Infrastructure cost of growth patterns | Depend on cost assumptions |
The current service level is R0: information and enquiries. An enquiry receives a reference and names the next step; applications, payments, compute allocations and registrations open only when their team, terms and review capacity exist.