Urban Flooding in India: Causes, Impacts, and Mitigation Strategies | UPSC

Introduction

• Urban flooding has emerged as a significant challenge in Indian cities, driven by factors like rapid urbanization, inadequate infrastructure, and climatic changes. 
• Recent incidents in Delhi, marked by extreme heat followed by unprecedented rainfall, underscore the urgency of addressing urban flooding. 

Causes of Urban Flooding:

Unplanned Rapid Urbanization:

• • Urban growth has led to the destruction of natural drainage systems, encroachment on floodplains and wetlands. For instance, the Yamuna floodplain in Delhi has faced significant encroachment.
  • Concrete construction reduces permeable surfaces, preventing natural water absorption and increasing surface runoff.
  • Changes in natural watershed boundaries disrupt the natural flow of water, contributing to increased flooding.

Ineffective Urban Governance:

• • Despite the 74th Constitutional Amendment Act, key responsibilities like urban planning and land use have not fully transferred to city governments.
  • Ambiguity in the structure of Urban Local Bodies (ULBs) results in uneven power distribution, leading to poor governance and mismanagement of waterlogging issues. For example, multiple agencies in Delhi manage roads and drains, causing coordination problems.

Inadequate Drainage Infrastructure:

• • Many cities rely on outdated colonial-era drainage systems designed for lower rainfall intensities. Mumbai’s drainage system, for example, is inadequate for handling recent heavy downpours.
  • The lack of capacity to manage increased water volumes leads to frequent overflows during heavy rains.

Climate Change and Extreme Weather:

• • The IPCC reports an increase in the frequency and intensity of extreme rainfall events in India.
  • These events result in higher water volumes than existing drainage systems can handle, and increased runoff due to reduced soil absorption.

Loss of Water Bodies and Green Spaces:

• • Major Indian cities have lost 70-80% of their water bodies over the last 40 years, as revealed by a study by the National Institute of Urban Affairs.
  • This loss reduces natural water storage capacity, increases surface runoff, and disrupts the natural water cycle.

Solid Waste Mismanagement:

• • Improper waste management clogs drainage systems, reducing their capacity. For instance, the Mithi River in Mumbai often gets clogged with waste, leading to waterlogging.

Groundwater Depletion and Land Subsidence:

• • Excessive groundwater extraction causes land subsidence, creating low-lying areas vulnerable to waterlogging.

Lack of Integrated Urban Water Management:

• • A fragmented approach due to poor coordination between departments handling water supply, sewage, and stormwater drainage exacerbates flooding. Delhi, for example, has 11 agencies responsible for roads and drains.

Siltation of Rivers and Water Bodies:

• • Significant siltation reduces the water holding capacity of lakes and rivers, impairing natural drainage systems.

High Population Density:

• • Increased paved surfaces due to rapid urbanization reduce natural water absorption and increase surface runoff, worsening waterlogging during heavy rains.

Read also : Urban Heat Island | UPSC

Impacts of Urban Flooding:

Loss of Lives and Injuries:

• • Urban flooding can lead to fatalities and injuries as people get trapped or swept away. The 2005 Mumbai floods resulted in over 1,000 deaths.

Damage to Infrastructure:

• • Flooding causes extensive damage to buildings, roads, bridges, and other infrastructure. The 2015 Chennai floods damaged numerous homes and public facilities.

Displacement of Vulnerable Populations:

• • Poor individuals are often forced to vacate their homes and seek temporary shelter, losing personal belongings and facing accommodation challenges.

Disruption of Vital Services:

• • Essential services such as electricity, water supply, and communication networks are disrupted, aggravating hardships and impeding rescue efforts.

Increased Risk of Waterborne Diseases:

• • Flooding elevates the risk of diseases like cholera, typhoid, and diarrhea. Srinagar’s 2014 floods saw a rise in waterborne diseases.

Economic Consequences:

• • Businesses face financial losses due to property damage and operational interruptions, while the government incurs significant expenses for rescue and relief operations. The 2015 Chennai floods caused an economic loss of approximately Rs 20,000 crore.

Mental and Psychological Stress:

• • The trauma, anxiety, and stress from flooding events affect the mental health of those impacted.

Government Initiatives:

National Level Initiatives:

• • National Urban Flooding Programme: Establishes a holistic approach to urban flood management with guidelines for risk assessment and mitigation strategies.
  • Smart Cities Mission: Integrates urban flood management, advocating for technology in real-time flood monitoring and early warning systems.
  • Atal Mission for Rejuvenation and Urban Transformation (AMRUT): Enhances urban infrastructure, focusing on stormwater drainage systems and allocating funds for upgrades.
  • National Disaster Management Authority (NDMA): Provides comprehensive guidelines for flood risk assessment and management.

State and City-Level Initiatives:

• • Mumbai: The BRIMSTOWAD project upgrades pumping stations, installs new ones, and desilts major nullahs before monsoon season.
  • Chennai: C-FLOWS (Chennai FLOod Warning System) predicts flooding from heavy rainfall, sea-level rise, and river water levels.
  • Kolkata: The Kolkata Environmental Improvement Project (KEIP) upgrades sewerage and drainage systems, installs new pumping stations, and renovates canals.
  • Bengaluru: Efforts include rejuvenating lakes, implementing rain gardens and bioswales, and removing stormwater drain encroachments.
  • Ahmedabad: The Sabarmati Riverfront development includes measures to prevent urban flooding.

Read also: Urban fires in India: Concept, Causes, Effects and Mitigation | UPSC

Way Forward:

Capacity Development of ULBs:

• • Encourage staff to acquire new skills with suitable incentives. State governments and ULBs should prioritize rebuilding the foundational structure of local government institutions, ensuring adequate staffing and establishing training facilities.

Water-Sensitive Urban Design and Planning:

• • City master plans should mandate vulnerability and risk assessments. Techniques such as green roofs, permeable pavements, and urban green spaces should be incorporated to absorb rainwater and minimize surface runoff.

Scientific Management Measures:

• • Begin with mapping areas vulnerable to waterlogging and use hydraulic and hydrological models to analyze flood patterns, incorporating results into urban master plans.

Decentralized Stormwater Management:

• • Promote rainwater harvesting, bioswales, and retention ponds to mitigate waterlogging locally. Bengaluru’s “A Million Recharge Wells” campaign, for instance, has improved groundwater levels and reduced flooding.

Smart Drainage Systems:

• • Utilize sensor-based drainage systems for real-time water level detection and regulation. Airborne laser terrain mapping (ALTM) can aid in urban planning and flood risk mapping.

Synergistic Approach:

• • Improve coordination between water resources and disaster management authorities for an integrated and coordinated approach.

Engagement with Grassroots Organizations:

• • Engage grassroots organizations to raise awareness and promote holistic flood risk management. The Environmentalist Foundation of India (EFI) in Chennai, for instance, has restored over 39 lakes, reducing surrounding area waterlogging.

Revival of Local Water Bodies:

• • Prioritize protection and restoration of traditional water bodies, integrating them into urban infrastructure. Biome Environmental Trust in Bengaluru has led in decentralized wastewater treatment and rainwater harvesting.

Green Infrastructure:

• • Implement green roofs, rain gardens, bioswales, permeable pavements, and urban green spaces to absorb rainwater and reduce strain on drainage systems.

Nature-Based Solutions:

• • Restore natural wetlands, create urban forests, and revitalize water bodies to enhance natural water absorption and reduce waterlogging.