Summary
- Over 880 million people in the global south live in slums, with one in three located in flood-prone areas.
- Countries like India, Bangladesh, DR Congo, and Indonesia are among the worst affected by disastrous floods in global south regions.
- Limited infrastructure, poor governance, and climate change are compounding urban flood vulnerability in informal settlements.
Disastrous Floods in Global South: Rising Waters and Urban Vulnerability
Slums in the global south are increasingly situated at the heart of a growing crisis: disastrous floods in global south nations are now affecting millions living in informal settlements. A recent study published in Nature Cities highlights that one in three slum dwellers live in floodplains, putting them directly in harm’s way as the intensity and frequency of floods continue to rise due to climate change and rapid urbanisation.
With more than 880 million people in the global south living in slums—areas characterised by insecure tenure, poor sanitation, and fragile housing—this vulnerability has grave implications. These communities are disproportionately located in zones where major floods have already occurred or are likely to strike again, including parts of India, Bangladesh, Nigeria, and Brazil.
The study, based on advanced satellite data, socioeconomic surveys, and machine learning models, maps out the direct correlation between informal urban growth and flood exposure. For instance, over 34 million slum residents in India alone live within floodplains. In countries like Sierra Leone, where over half the population resides in slums, the flood vulnerability is acute.
Third of ‘slum residents’ in global-south are exposed to ‘disastrous’ flood risks | @storyofsvetlana w/ comment from @nha3383 @GodeBola1
— Carbon Brief (@CarbonBrief) July 28, 2025
Read here: https://t.co/3INRCymJ8M pic.twitter.com/zTsLUZ2Mj3
Hidden Hotspots and Societal Impact
- Sub-Saharan Africa has the highest percentage of slum dwellers living in floodplains—around 80%.
- Urban slums in Rourkela (India) and Kinshasa (DR Congo) recently witnessed deadly floods, underlining the study’s findings.
While the world focuses on rising sea levels and melting glaciers, the immediate and compounding threat of disastrous floods in global south cities remains underreported. In cities like Dar es Salaam, Jakarta, and Rio de Janeiro, informal settlements spring up along rivers, wetlands, and other marginal lands because these areas are the only affordable options available to low-income migrants.
In Kinshasa, a fast-growing city with limited urban planning, 165 people died during floods that swept through 13 slum communes. Similarly, slums in Rourkela were inundated by torrential monsoon rains. These events are no longer anomalies—they are becoming seasonal occurrences.
Slum residents are often blamed for “encroaching” on hazardous land, yet the reality is that land scarcity and exclusionary policies leave them no alternative. Low-lying and flood-prone zones are usually cheaper, pushing marginalised populations into harm’s way. This underscores how disastrous floods in global south regions are not merely natural events but social and economic injustices in motion.
Structural Neglect In The Case OF Disastrous Floods In Global South and Climate Stress
- Slums are typically excluded from city planning, drainage infrastructure, or formal housing schemes.
- Climate change has intensified extreme rainfall in equatorial and tropical zones of the global south.
Disastrous floods in global south areas are magnified by state inaction and poor governance. The study points out that governments are often reluctant to formally recognise slums, fearing legal obligations to provide basic services. This denial often backfires, leaving entire communities unprotected.
For example, during the Karachi floods of 2022, thousands living near drainage channels were labeled as “encroachers” despite having lived there for decades. Rather than receiving support or rehabilitation, they were evicted, often without compensation.
This misalignment between law, policy, and lived realities leads to harsh humanitarian outcomes. According to Dr Nausheen Anwar, director of the Karachi Urban Lab, the judicial system has sometimes enabled mass displacements in the name of flood prevention, leaving the urban poor even more vulnerable.
As global temperatures rise, rainfall variability is increasing. In the Congo Basin, formerly manageable rain events now result in catastrophic floods. Dr Gode Bola, a climate risk expert in the region, notes that “floods have become larger, more frequent, and more difficult for communities to adapt to.” This intensification is especially devastating for slum residents with no savings or relocation options.
Data-Driven Governance and Urban Resilience
- In countries with frequent disastrous floods in global south, slum residents account for 41% of those living in flood-prone zones, despite being only 35% of the population.
- Official data shows more than 56% of Bangladesh’s slum dwellers live in high flood-risk areas.
The authors of the study argue that their data can be a catalyst for change—if cities are willing to act. They advocate for data-driven urban policies that integrate slum dwellers as stakeholders rather than passive recipients or illegal occupants. Recognising slums in city plans is the first step toward mitigating disaster risk.
Urban flood resilience in the matter of disastrous floods in global south must prioritise community empowerment, not just engineering solutions. This includes:
- Building decentralised drainage and rainwater harvesting systems.
- Training slum residents in waste management and basic flood response.
- Providing access to microfinance or relocation grants for at-risk populations.
These interventions are not simply humanitarian measures—they are necessary for the sustainable development of rapidly urbanising regions.
Furthermore, better inter-agency coordination is vital. Ministries of housing, water, climate, and disaster management need unified plans that go beyond election cycles. While many countries have signed international frameworks like the Sendai Framework for Disaster Risk Reduction, the translation of these commitments into action has been limited.
What Lies Ahead for At-Risk Urban Communities
- Climate-induced migration and urban population booms may double slum populations by 2050.
- Without intervention, disastrous floods in global south will likely displace tens of millions.
The findings of this study are not isolated—they are a warning. As urbanisation accelerates and climate extremes grow, more and more people will be driven into risky geographies with no formal support structures.
Major cities in Asia and Africa—such as Dhaka, Lagos, and Manila—already face severe housing crises. If no proactive action is taken, disaster will become the default condition for the urban poor. Disastrous floods in global south nations may become a permanent feature, not just a seasonal event.
Final Thoughts On Disastrous Floods In Global South
Urban planners and policymakers must embrace a human-centred approach. That means understanding not only the geographic risk but also the economic, legal, and cultural barriers slum residents face. Without addressing the root causes of why people settle in flood-prone areas—poverty, housing shortages, and exclusionary planning—mitigation efforts will fall short.
In the words of Dr Anwar, “Data speaks for itself… We need that to buttress the sort of changes we want to make on ground.” The time to act is not after the flood has come, but before.
