Flooding remains one of the most severe hazards worldwide. Recent studies reveal over 2.3 billion people face flood exposure annually. India alone has more than 600 million at risk. A 2025 study analysed satellite images of informal settlements in 129 low- and middle-income countries. It compared these with maps of 343 major floods. The research found India leads with the highest number of slum dwellers living in floodplains, over 158 million. Most are in the Ganga river delta, a naturally flood-prone region.
Flood Exposure in Informal Settlements
Around 33% of informal settlements in the Global South lie in flood-exposed areas. This includes 445 million people across 908,077 households in 67,568 clusters. South Asia has the largest concentration, with India, Bangladesh, Pakistan, and Indonesia as hotspots. Other notable regions include parts of Africa, northern Morocco, and coastal Brazil. Despite repeated floods, these areas have limited flood risk management.
Urbanisation and Settlement Patterns
Settlement types vary by region. Latin America and the Caribbean have 80% urbanisation, with 60% of informal settlements in cities. Sub-Saharan Africa has lower urbanisation; 63% of its informal settlements are rural. In India, 40% of slum dwellers live in urban or suburban areas. Economic needs and social vulnerability push people to settle in floodplains. Low land costs in flood zones attract poorer populations.
Socioeconomic and Institutional Vulnerability
Flood vulnerability depends on education, income, and institutional support like flood insurance. Wealthier regions use flood insurance and infrastructure such as levees to reduce risk. In contrast, poorer regions lack these protections. Slum dwellers are 32% more likely to live in floodplains due to cheaper land. Cities like Mumbai, Jakarta, and Bengaluru show strong links between informal settlements and flood risk.
Infrastructure, Real Estate, and Displacement
Flood-prone areas are often avoided by large developers. This leaves cheaper land for informal settlements. Poor infrastructure and inadequate drainage worsen flood impacts. Gentrification pushes vulnerable communities into higher risk zones. Housing shortages and lack of basic services cluster populations in small areas. This increases exposure and reduces resilience.
Policy Implications and Sustainable Development Goals
The 2030 UN Sustainable Development Goals target poverty, clean water, sanitation, and climate action. The study urges a human-centric approach to flood risk management. Governments should collaborate with communities for disaster preparedness. Skills in sanitation, waste management, and drainage can improve resilience and create jobs. Data-driven methods like machine learning can enhance flood risk prediction and planning.
Future Research Directions
Researchers plan to study slum growth, climate change, and migration effects on flood risk. Timewise analysis will help predict future vulnerabilities. This will support more effective flood adaptation strategies in vulnerable regions.
Questions for UPSC:
- Taking example of informal settlements in floodplains, discuss the challenges of urbanisation and climate change in developing countries.
- Examine the role of socio-economic factors and institutional mechanisms like flood insurance in managing disaster vulnerability.
- Analyse the impact of infrastructure development and real estate dynamics on vulnerable populations in flood-prone urban areas.
- With suitable examples, discuss the importance of data-driven approaches and machine learning in disaster risk management and sustainable development.
