Flood Risk and Slum Settlements

A recent global study published in Nature Cities highlights alarming trends in flood risks and slum settlements, with India emerging as the worst-affected country in terms of slum clusters located in flood-prone areas. This issue, exacerbated by rapid urbanization, poor infrastructure, and climate change, calls for urgent action to protect vulnerable populations in urban slums.

Key Findings on Flood-Exposed Slum Dwellers:

• India’s Vulnerability:

  • Over 158 million slum dwellers in India live in flood-prone areas, primarily in the Ganga River delta, a naturally flood-prone region.

  • 40% of slum dwellers reside in urban and suburban areas with high flood risk due to overcrowding and poorly managed infrastructure.

  • Other countries with significant vulnerable populations include Indonesia, Bangladesh, and Pakistan.

  Global Context:

  • Slum dwellers are 32% more likely to live in floodplains compared to other populations.

  • In cities like Mumbai and Jakarta, the flood risk is closely tied to slum density, indicating that these populations are disproportionately exposed to flood threats.

  Disproportionate Vulnerability in the Global South:

  • In low- and middle-income countries, 33% of informal settlements are located in areas exposed to flooding.

  • Hotspots outside South Asia include Rwanda, northern Morocco, and coastal Rio de Janeiro.

  Impact on Socioeconomic Inequality:

  • Slum dwellers face severe flood impacts, including job loss, displacement, and limited access to healthcare and education.

  • Lack of infrastructure and social safety nets exacerbates these vulnerabilities.

Factors Responsible for Flooding in India:

1. Riverine Floods:

   • Caused by overflowing rivers due to heavy rainfall, snowmelt, or dam failures.

   • The Brahmaputra, Ganga, and Krishna River basins are most prone to flash floods, with the Himalayan regions facing higher risks due to steep slopes.

2. Urban Expansion:

   • Rapid urban growth, especially in cities like Bengaluru and Mumbai, is encroaching upon floodplains, worsening the risk of flooding.

   • India ranked 3rd globally (1985–2015) in urban growth into flood-prone areas.

3. Flash Floods:

   • Flash flood incidents have increased, with a rise from 132 incidents in 2020 to 184 in 2022. These are caused by extreme rainfall combined with saturated soil.

   • Notable events include Himachal Pradesh (2025), Wayanad (2024), and Ladakh (2024).

4. Climate Change:

   • Extreme rainfall events have doubled from 1981 to 2020, and monsoon rains have increased by 56%, significantly heightening flood risks.

5. Poor Drainage:

   • Cities like Delhi, Mumbai, Hyderabad, and Bengaluru face waterlogging due to outdated or blocked drains, worsening urban flooding.

6. Weak Oversight:

   • Encroachments and plastic waste often block stormwater drains, as seen in the 2015 Chennai floods.

7. Lack of Local Strategies:

   • Absence of region-specific flood risk assessments hampers forecasting, land-use planning, and infrastructure improvements.

Status of Slums in India:

1. Defining Slums:

   • According to the Pranab Sen Committee (2010), slums are defined as settlements with poorly built houses, inadequate sanitation, and crowded living conditions.

   • UN-HABITAT defines slums as settlements lacking basic services like durable housing, clean water, sanitation, and secure tenure.

2. Slum Population in India:

   • According to Census 2011, 17% of India’s urban population resides in 1.39 crore slum households.

   • States like Maharashtra, Andhra Pradesh, Uttar Pradesh, and West Bengal have the highest slum populations.

   • Major cities like Mumbai and Kolkata show the strong correlation between urban growth and slum formation.

3. Regulations:

   • Housing and slum rehabilitation fall under state jurisdiction in India, guided by acts like the Slum Areas (Improvement and Clearance) Act, 1956.

Measures for Sustainable Slum and Flood Management:

1. Region-Specific Adaptation:

   • Develop flood risk management strategies based on local topography and soil conditions, improving early warning systems and disaster preparedness.

2. Restrict Urban Expansion in Floodplains:

   • Enforce zoning laws and promote flood-resilient infrastructure under initiatives like the Smart Cities Mission.

3. Upgrading Informal Settlements:

   • Under schemes like PMAY (Pradhan Mantri Awas Yojana), improve flood resilience through elevated housing, better drainage, and improved infrastructure in slums.

4. Data-Driven Risk Assessment:

   • Use tools like satellite imagery, Integrated Flood Warning Systems (IFLOWS), and data from the India Meteorological Department to monitor flood risks and improve flood forecasting.

5. Adopt the Sponge City Concept:

   • Cities like Shanghai and Mumbai are implementing the Sponge City model, using green roofs, permeable surfaces, and rain gardens to absorb excess rainwater and reduce flood risks.

6. Climate Change Adaptation:

   • Incorporate climate resilience into urban planning and restore urban lakes and wetlands to manage floods, as seen with Bengaluru’s Jakkur Lake restoration.

Conclusion:

As the 2030 Agenda for Sustainable Development approaches, urgent action is required to address flood vulnerability in slum settlements. These efforts should align with key SDGs:

• SDG Goal 11 (Sustainable Cities and Communities)

• SDG Goal 6 (Clean Water and Sanitation)

• SDG Goal 1 (No Poverty)

Addressing these challenges is essential for improving the lives of millions of slum dwellers already exposed to the devastating impacts of floods. Efforts must be ramped up to create resilient urban infrastructure and flood-resistant housing, ensuring that no community is left behind.