GCRI · Cities and Built Environment
Informal settlements
Informal settlements are home to a large share of urban residents in many countries. They are built outside formal planning and titling, often on land others left because it floods, slides or lies beside hazards, and they frequently lack water, sanitation and drainage. This page sets out how informal settlements form and how risk concentrates in them, how they are mapped with residents, and what evidence serves the governments and community organisations that work to upgrade them.
Informal settlements on the record.
Informal settlements: how the risk develops.
Service access, exposure and inclusion. The dossier below sets out how the risk develops, what is measured, where the data come from, how it is modelled and who decides.
Settlement fills the gaps
When formal housing and land are unaffordable or unavailable, people build on land that is left over: riverbanks, slopes, railway edges and wetlands. Location brings hazard.
Services arrive late or not at all
Without recognised tenure, utilities and governments often do not extend water, sanitation, drainage or waste collection, which raises health and flood risk.
Construction is incremental
Homes are built and extended step by step with available materials and labour. Structures can be vulnerable to fire, earthquakes and storms, though many residents invest heavily in them.
Communities organise their own resilience
Savings groups, community federations and local leaders map settlements, negotiate with authorities and act in emergencies. Upgrading works best when residents lead.
Urban signals in India.
Population density, night lights and daytime surface heat over India, from NASA GIBS. Each layer carries its own date.
The interactive map needs JavaScript; the layer list and sources are below.
Layers 3
Urban signals, for this page
About this layer
- Evidence
- Estimated
- Source
- Gridded Population of the World v4.11 (NASA SEDAC (CIESIN, Columbia University))
- Provider
- NASA SEDAC (CIESIN, Columbia University)
- Licence
- CC BY 4.0
- Vintage
- null; Census-based estimate, static (2020)
- Resolution
- about 1 km grid
- Uncertainty
- Census-based estimate of people per square kilometre in 2020, shown as exposure context; not a count of people affected by any hazard.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed
- Source
- VIIRS Black Marble (VNP46A2) (NASA LAADS DAAC)
- Provider
- NASA LAADS DAAC
- Licence
- NASA open data
- Vintage
- daily; Satellite radiance, corrected for moonlight and atmosphere
- Newest at build
- 2026-10-12
- Resolution
- about 500 m grid
- Uncertainty
- Satellite night-time radiance for the date shown; lights are a proxy for electricity use and outages, not a measurement of supply or access.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed (persistent cloud still leaves gaps)
- Source
- VIIRS NOAA-20 Level 3, 8-day (NASA LANCE)
- Provider
- NASA LANCE
- Licence
- NASA open data
- Vintage
- 8-day; Satellite 8-day composite; persistent cloud still leaves gaps
- Newest at build
- 2026-09-14
- Resolution
- about 1 km grid
- Uncertainty
- Satellite skin temperature of the ground over the 8 days ending on the date shown, a heat exposure indicator; not air temperature, heat index or a heat warning.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed
- Source
- VIIRS NOAA-20 corrected reflectance (NASA LANCE)
- Provider
- NASA LANCE
- Licence
- NASA open data
- Vintage
- daily; Satellite image
- Newest at build
- 2026-10-14
- Resolution
- about 250 m grid
- Uncertainty
- Satellite image. Satellite or model raster as the provider publishes it. Clouds, swath gaps and retrieval error leave gaps and noise; values are indicators, not measurements at a place.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Modelled (latest year GIBS publishes)
- Source
- MODIS Terra and Aqua land cover (MCD12Q1) (NASA LP DAAC)
- Provider
- NASA LP DAAC
- Licence
- NASA open data
- Vintage
- yearly; Satellite classification; latest year GIBS publishes
- Newest at build
- 2024-01-01
- Resolution
- about 500 m grid
- Uncertainty
- Satellite land cover classes for the year shown, including croplands; a classification with known errors, not a farm register.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed (clouds leave gaps)
- Source
- OMI Aura (NASA GES DISC)
- Provider
- NASA GES DISC
- Licence
- NASA open data
- Vintage
- daily; Satellite retrieval; clouds leave gaps
- Newest at build
- 2026-10-10
- Resolution
- about 2 km grid
- Uncertainty
- Satellite column of nitrogen dioxide in the lower atmosphere on the day shown, mostly from combustion; not a ground-level concentration or a health warning.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
Keyboard, with the map focused
Hold Ctrl or ⌘ and scroll to zoom
Latest available
NASA GIBS / EOSDIS · ASTER GDEM (METI, NASA) · Blue Marble (NASA) · © OpenStreetMap contributors (ODbL) · Natural Earth
Loading the latest NASA imagery.
Drag to move. Ctrl or ⌘ and scroll, pinch or the buttons to zoom; hover for the values under the pointer; reset returns to the region.
Urban signals, framed on India.Satellite and model products as NASA publishes them, each with its own date. They are indicators, not assessments of any place.
Data: NASA GIBS · ASTER GDEM · Blue Marble · © OpenStreetMap contributors · Natural Earth · NASA EONET · U.S. Geological Survey · NASA JPL OPERA DIST-ALERTSources and licences
- We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- Center for International Earth Science Information Network (CIESIN), Columbia University. 2018. Gridded Population of the World, Version 4 (GPWv4): Population Density, Revision 11. NASA Socioeconomic Data and Applications Center (SEDAC). Licensed under CC BY 4.0. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). doi:10.7927/H49C6VHW. CC BY 4.0
- VIIRS Black Marble night-time lights, NASA Goddard Space Flight Center; distributed by the NASA Level-1 and Atmosphere Archive and Distribution System (LAADS DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- VIIRS near-real-time products (flood, land surface temperature, snow cover, corrected reflectance), NASA LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- MODIS land products (vegetation indices, gross primary production, land cover), NASA LP DAAC and LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- OMI nitrogen dioxide (Aura) and OMPS aerosol index (Suomi NPP), NASA; distributed by the NASA GES DISC; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- ASTER GDEM is a product of METI and NASA (ASTER Global Digital Elevation Model V003, NASA LP DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). Cite as: NASA/METI/AIST/Japan Spacesystems and U.S./Japan ASTER Science Team (2019). ASTER Global Digital Elevation Model V003. doi:10.5067/ASTER/ASTGTM.003. NASA open data
- Made with Natural Earth. Free vector and raster map data @ naturalearthdata.com. Public domain
- © OpenStreetMap contributors (ODbL), via NASA GIBS (coastlines, boundaries, roads and place names). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). ODbL
- Blue Marble, NASA Earth Observatory; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- Context on the globe and flat map: coastlines, boundaries, roads and place names from NASA GIBS reference layers (OpenStreetMap data, ODbL, © OpenStreetMap contributors); Blue Marble imagery as an optional base; 3D terrain and the elevation read-out from the ASTER GDEM elevation colour index (5 m to 200 m classes, exaggerated for legibility). Boundaries are drawn as published and imply no position on any territory.
- Live events: NASA Earth Observatory Natural Event Tracker (EONET); events are indicative and keep their original source links.
- Live: NASA EONET Events are indicative, not authority warnings.
- Live: U.S. Geological Survey Events are indicative, not authority warnings.
- Observed (EO): NASA JPL OPERA DIST-ALERT (contains modified Copernicus Sentinel data 2026). We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
- NASA GIBS: We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
- Air quality forecast, 5 days, PM2.5 (CAMS via Open-Meteo): Contains modified Copernicus Atmosphere Monitoring Service information 2026.
- Past year, daily temperature and sunshine (NASA POWER): These data were obtained from the NASA Langley Research Center (LaRC) POWER Project funded through the NASA Earth Science/Applied Science Program..
- Weather data by Open-Meteo.com (https://open-meteo.com/), licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).
- Optional layers (16 sources in the layer list: live, forecast, observed and context) print their provider credit on the map and here when switched on; forecasts are model output and derived indices are estimates.
Layers and dates
- Population density, 2020: Population: CIESIN, Columbia University, Gridded Population of the World v4.11 (2018), NASA SEDAC, CC BY 4.0 · static
- Night-time lights, daily: VIIRS Black Marble (VNP46A2), NASA LAADS DAAC · 12 Oct 2026
- Land surface temperature, day, 8-day composite: VIIRS NOAA-20 Level 3, 8-day, NASA LANCE · 14 Sep 2026
- True colour: VIIRS NOAA-20 corrected reflectance, NASA LANCE · 13 Oct 2026
- Land cover type (IGBP), yearly: MODIS Terra and Aqua land cover (MCD12Q1), NASA LP DAAC · 2024
- Nitrogen dioxide, lower atmosphere column: OMI Aura, NASA GES DISC · 10 Oct 2026
Informal settlements face every domain’s risks at once.
Settlement evidence is designed for the Evidence Brief series, with residents involved in collecting it. SDG indicator 11.1.1 tracks the urban population in slums and informal settlements.
- Community-led enumerations shared with consent.
- Upgrading evaluations.
Asset register with hazard overlay.
The screen a team would use to follow this subject: its measures, states and decisions. Names are examples and values are illustrative.
Asset register with hazard overlay
Informal settlements · Riverside ward · Flood 1-in-100 overlay
Hazard overlay
flood scenario on asset register
RiverFlood extentExposed asset
Exposed assets
| H-01 | Clinic | 0.8 |
| S-07 | School | 0.6 |
| E-03 | Substation | 1.5 |
| W-02 | Pump station | 0.7 |
Adaptation options
| Raise substation E-03 | 1 | Medium | Service continuity | Design |
| Retention park upstream | 10 | High | Heat, recreation | Feasibility |
| Flood-proof clinic H-01 | 1 | Low | Health access | Funded |
What is measured, and how well.
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 |
|---|---|---|---|---|
| Urban population in slums or informal settlements | percent of urban population | per survey | SDG indicator 11.1.1 | ESTIMATED |
| Households with basic water and sanitation | percent of households | per survey | Household surveys and community enumerations | REPORTED |
| Informal settlements in hazard zones | count and area | per assessment | Settlement maps overlaid on hazard maps | ESTIMATED |
| Settlements with community-led profiles | count | per assessment | Community enumeration records | REPORTED |
| Evictions | count of households evicted | annual | Monitoring by civil society and authorities | REPORTED |
| Households in upgrading programmes | count | annual | Programme records | REPORTED |
Model informal settlements as a system. Run the cascade.
Assembled from the Nexus Standards area profile Cities and the built environment: the hazards it names, the systems and sectors that carry the loss, the controls that dampen it and the data that observe it. Choose the components, pick an initiating hazard and step through the cascade. The Map view places the run on an example geography with open data. Every coupling weight is a stated assumption you can change. A teaching model, not a forecast, an assessment or a certification. To model a place of your own choosing, open the full System Builder.
Hazards
- Ice-jam flood
- Earthquake
- Dam failure
- Aftershock sequence (set off downstream)
- Fault surface rupture (set off downstream)
- Soil liquefaction (set off downstream)
- Slope slide (set off downstream)
- Rockfall (set off downstream)
- Tsunami (set off downstream)
- Building collapse (set off downstream)
- Widespread power outage (set off downstream)
- Water supply failure (set off downstream)
- Mass displacement (set off downstream)
- Disaster and conflict debris (set off downstream)
- River flood (set off downstream)
- Flash flood (set off downstream)
- Turbidity current (set off downstream)
- Seismically and structurally vulnerable stock (set off downstream)
Systems and couplings
- Cities and the built environment
- Construction and real estate Coupling
- Water utilities and basins Coupling
- Public sector and government Coupling
- Energy utilities and grids Coupling
Controls
NS-0Constitution and principlesNS-3Risk record UNIs (grammar, legacy crosswalk, allocation authority)NS-5Figure, map and visualisation standard (with the UI/UX kit)NS-9Contextual UNIs (deployments, instances, programme instances)NS-10Policies and clauses (machine-readable obligations: definition, binding, evaluation and enforcement)NS-11Verification and monitoring (evidence, attestations, zero-trust conformance observation)NRS-X5Cities and built environment riskNRS-H91Hazard family: Urban and building-stock stress (NHS-1 infra.urban)NRS-H113Hazard family: Financial-system fragility (NHS-1 soc.financial-system)NRS-K7Domain pack profile: Cities urban (DOMAIN-007)NRS-H31Hazard family: Persistent and bioaccumulative substances (NHS-1 poll.persistent)NRS-H34Hazard family: Waste and residue failures (NHS-1 poll.waste)
Observation
- Global Human Settlement Layer (listed for reference)
- WorldPop gridded population (listed for reference)
- Overture Maps buildings theme (listed for reference)
- OpenStreetMap (listed for reference)
- World Development Indicators (listed for reference)
- Direct economic loss in relation to global GDP, damage to critical infrastructure and number of disruptions to basic services, attributed to disasters
- Proportion of local governments that adopt and implement local disaster risk reduction strategies in line with national strategies
- Proportion of urban population living in slums, informal settlements or inadequate housing
- Percentage of local governments that adopt and implement local disaster risk reduction strategies in line with national strategies
Example geography
- India: 65 hexagonal cells
- Surface water through cloud, 30 m (OPERA DSWx-S1 radar), NASA GIBS
- Rain rate, last half hour (IMERG), NASA GIBS
- Night lights tonight, outages (VIIRS Day/Night Band), NASA GIBS
- Surface soil moisture (SMAP), NASA GIBS
Where the evidence comes from.
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 |
|---|---|---|
| UN-Habitat SDG 11.1.1 data | Share of urban population in slums, informal settlements or inadequate housing | Public, UN-Habitat terms (to check) |
| Slum Dwellers International Know Your City profiles | Community-collected settlement profiles | Public summaries, terms to check |
| Open machine-learned building footprint datasets | Building outlines derived from satellite imagery where cadastral data are missing | Open, CC BY 4.0 or ODbL depending on the release |
| Demographic and Health Surveys and Multiple Indicator Cluster Surveys | Household services and dwelling characteristics | Free with registration, survey terms |
| OpenStreetMap community mapping | Streets, buildings and services mapped with residents | Open, ODbL |
How informal settlements is modelled, measured and tested.
The model, its assumptions, its data and its uncertainty, in the form a scientist or engineer would check. Structures follow published methods. The values drawn are illustrative, not findings.
System model
The couplings between the systems in informal settlements: signs of influence, a reinforcing and a balancing loop, and cross-links where stress jumps.
Who decides, and what the evidence serves.
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 governments | Which settlements to upgrade and how to secure tenure | Service gap and hazard analyses; community profiles |
| National housing and land ministries | How to recognise tenure and fund upgrading | SDG 11.1.1 evidence; programme results |
| Community federations and organisations | What to prioritise in negotiations with authorities | Community-led profiles and maps |
Outputs this topic produces
- Settlement maps produced with residents and their consent
- Hazard and service gap analyses for upgrading
- Housing safety guidance suited to incremental construction
- Case studies of community-led upgrading
What experts ask.
- 01
What services do residents have?
Access to water, sanitation, drainage, electricity, waste collection and transport, and its reliability and cost.
- 02
Why are these settlements exposed?
How land markets and exclusion push settlement onto floodplains, slopes and waste sites.
- 03
What upgrading works?
Evidence on in-situ upgrading, tenure security and relocation, and their effects on residents.
- 04
How are residents counted?
How settlements are mapped and enumerated, and who controls that data.
What drives the risk.
Informality is a response to unaffordable formal housing and slow land administration. People build where they can, and services follow late or not at all. Lack of tenure security discourages investment in safer construction.
Exposure is compounded. Poor drainage turns rainfall into flooding; dense construction with combustible materials spreads fire; lack of sanitation spreads disease. Residents often pay more per unit of water or power through informal providers.
Eviction and relocation carry their own risks. Moving people away from livelihoods and social networks can increase vulnerability even when the new site is less exposed.
Strengths are often overlooked. Dense social networks, savings groups and local builders are resources for preparedness and recovery, and upgrading that works with them tends to last longer than programmes designed from outside.
How evidence is gathered, and where it stops.
| Method or data | What it shows | Its limit |
|---|---|---|
| Community enumeration | Households, tenure and services, gathered by residents | Requires trust, consent and time |
| High-resolution imagery | Settlement extent and density | Cannot show tenure, services or people |
| Household surveys | Service access and cost | Under-sampling of unregistered households |
| Participatory risk mapping | Local hazard knowledge | Data protection is essential |
How it is studied, and what the methods cannot say.
- 01Geospatial information systemsUrban exposure databases · Community mapping · Hazard overlay for planningApplied here
- 02Social and behavioural scienceHousing and tenure surveys · Participatory planning research · Displacement studiesApplied here
- 03Structural and earthquake engineeringUrban building vulnerability profiles · Retrofit of schools and housingApplied here
- 04Water and environmental engineeringUrban drainage design · Sanitation for unserved areas · Waste and drainage linksApplied here
- 05Spatial statistics and geostatisticsSmall-area estimation · Spatial clustering of disadvantage · Interpolating urban temperatureApplied here
Where this page’s references lead.
The bodies and documents this page is read against. Status and editions change; each link goes to the issuing body.
Questions and answers.
What is an informal settlement?
What is slum upgrading?
Why involve residents in mapping?
Does mapping informal settlements put residents at risk?
Is relocation recommended for exposed settlements?
Why call it informal rather than illegal?
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