Global Flood Risk and Informal Settlements
Flooding remains a critical global hazard in 2025, affecting billions annually. A recent study using satellite data reveals that informal settlements, especially in low- and middle-income countries, face disproportionate flood risks. India leads with the highest number of slum dwellers in flood-prone areas, emphasising urgent challenges in urban planning and disaster management.
Global Flood Exposure
Over 2.3 billion people worldwide are exposed to flooding every year. In India alone, more than 600 million people face risks from coastal and inland floods. Informal settlements in vulnerable floodplains are widespread in the Global South, where 33% of such settlements have already experienced floods. This amounts to around 445 million people living in over 67,000 clusters across 129 countries.
India’s Flood Vulnerable Slum Population
India has the largest concentration of slum dwellers in floodplains—over 158 million people. Most reside in the Ganga delta, a naturally flood-prone region. Northern India leads in numbers, followed by Indonesia, Bangladesh, and Pakistan. These populations are exposed due to factors like poverty, lack of affordable housing, and proximity to job opportunities in urban areas.
Patterns of Settlement and Urbanisation
Settlement types vary by region. Latin America and the Caribbean show high urbanisation rates, with 80% urban settlements. In contrast, Sub-Saharan Africa has mostly rural informal settlements. In India, 40% of slum dwellers live in urban or suburban areas. Informal settlements often form in floodplains because land is cheaper and more accessible for low-income groups.
Socioeconomic and Institutional Vulnerabilities
Flood vulnerability depends on education, income, and institutional support like flood insurance. In wealthier regions, floodplains are often protected by infrastructure and insurance, attracting affluent residents. In poorer regions, floodplains offer affordable housing but come with high risk. Informal settlements are usually made of temporary materials and lack basic services, increasing their exposure.
Impact on Livelihoods and Services
Floods cause job losses and disrupt access to essential services for vulnerable communities. Poor infrastructure and inadequate drainage worsen the situation. In cities like Bengaluru and Mumbai, informal settlements are often located in flood-prone areas avoided by formal real estate development, denoting social and economic inequities.
Role of Data and Technology in Flood Risk Analysis
The study used machine learning to analyse satellite imagery and identify vulnerable settlements. This approach helps extract detailed socioeconomic data and map flood risks more accurately. Future research aims to predict changes in flood risk by studying slum growth, climate change, and migration patterns.
Policy Implications and Sustainable Development Goals
Addressing flood risk in informal settlements is critical for achieving the UN’s Sustainable Development Goals by 2030. Strategies must focus on human-centric solutions rather than just geographic risk zones. Collaboration between governments and communities can improve infrastructure, sanitation, and waste management, enhancing resilience and creating jobs.
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