The Global Centre for Risk and Innovation (GCRI)
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 organizations that work to upgrade them.
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For informal settlements, in GCRI's spatial-intelligence reading, the map opens on population density, true-colour imagery and night lights 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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Informal settlements are residential areas where residents lack secure tenure and homes often lack basic services and planning approval. They form on land others left, frequently hazardous, and services arrive late. Community organizations map and upgrade them, and upgrading works best when residents lead and their data are protected.
The working screen behind this subject: its structure, terms and states. Names are placeholders and values illustrative.
Informal settlements · Riverside ward · Flood 1-in-100 overlay
flood scenario on asset register
RiverFlood extentExposed asset
| H-01 | Clinic | 0.8 |
| S-07 | School | 0.6 |
| E-03 | Substation | 1.5 |
| W-02 | Pump station | 0.7 |
| 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 |
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.
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.
Without recognised tenure, utilities and governments often do not extend water, sanitation, drainage or waste collection, which raises health and flood risk.
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.
Savings groups, community federations and local leaders map settlements, negotiate with authorities and act in emergencies. Upgrading works best when residents lead.
Each term as this page uses it. Where a standard-setting body defines the term, the wording follows that body.
| Term | Definition |
|---|---|
| Slum | A household or area lacking one or more of improved water, sanitation, durable housing, sufficient space or secure tenure, in UN-Habitat usage. |
| Slum upgrading | Improving informal settlements in place through tenure, services and housing improvements. |
| Community enumeration | A survey of a settlement carried out by its own residents. |
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 |
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 |
|---|---|---|
| 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 |
| Google Open Buildings and Microsoft building footprints | Building outlines derived from imagery | Open, CC BY 4.0 and ODbL respectively |
| 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 |
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 organizations | What to prioritise in negotiations with authorities | Community-led profiles and maps |
Access to water, sanitation, drainage, electricity, waste collection and transport, and its reliability and cost.
How land markets and exclusion push settlement onto floodplains, slopes and waste sites.
Evidence on in-situ upgrading, tenure security and relocation, and their effects on residents.
How settlements are mapped and enumerated, and who controls that data.
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.
| 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 |
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.