Urban Flooding in India-Causes, Impacts and Remedies – Explained, pointwise

After enduring extreme temperatures nearing 50 degrees Celsius, Delhi residents are now dealing with unprecedented rainfall, causing severe waterlogging and chaos across the capital. Following one of its hottest periods on record, Delhi received a staggering 228.1 mm of rain in just 24 hours. This amount surpasses Delhi’s average rainfall for the entire month of June, transforming the recent relief from heat into widespread disruption.

Over the past few years, India has seen an increase in the frequency of urban flooding in Indian cities. For instance, Hyderabad in 2000 and 2020, Ahmedabad in 2001 and 2020, Delhi in 2002, 2003, 2009 and 2010, Chennai in 2004 and 2015, Mumbai in 2005, Surat in 2006, Kolkata in 2007, and Srinagar in 2014 are a few of the most prominent ones.

Urban Flooding has become a persistent challenge, aggravated by rapid urbanization, inadequate infrastructure, and changing climatic patterns.During the monsoon season, cities across India often face flooding of streets, homes, and public areas because drainage systems are overwhelmed and urban surfaces do not absorb water. This problem disrupts daily life and poses risks to public health, infrastructure, and economic activities.

Thus, understanding the causes and consequences of urban flooding is important for implementing effective mitigation strategies and ensuring sustainable urban development in the face of increasing urban populations and climate uncertainties.

What are the causes behind the urban flooding phenomenon?

1) Unplanned Rapid Urbanization-Unplanned urban growth has destroyed natural drainage systems, leading to encroachment on floodplains and wetlands, less permeable surfaces due to widespread concrete construction, and changes in natural watershed boundaries..

2) Lack of Effective Urban Governance-Despite the 74th Constitutional Amendment Act, key areas such as urban planning, land use, and economic development have not fully transferred to city governments as required. The structure of Urban Local Bodies (ULBs) lacks clarity that  leads to uneven distribution of power between elected representatives and executive wings.This leads to poor urban governence and mismangement of waterlogging issues.

3) Inadequate and Outdated Drainage Infrastructure:Many Indian cities are still reliant on colonial-era drainage systems designed for rainfall intensities of 20-25mm per hour, which are inadequate for current precipitation patterns. This results in insufficient capacity to handle increased water volume and frequent overflow during heavy rainfall,

4) Climate Change and Extreme Weather Events-The Intergovernmental Panel on Climate Change (IPCC) reports indicate an increase in the frequency and intensity of extreme rainfall events in India.This leads  to a higher volume of water than drainage systems can handle and increased runoff due to the soil’s inability to absorb water quickly.

5) Loss of Water Bodies and Green Spaces: A study by the National Institute of Urban Affairs revealed that major Indian cities have lost 70-80% of their water bodies over the last 40 years.This has led to reduced natural water storage capacity, increased surface runoff, and disruption of the natural water cycle.

6) Solid Waste Mismanagement–Improper solid waste management is choking drainage systems. This causes clogged drains and reduced water flow capacity leading to waterlogging of cities.

7) Groundwater Depletion and Land Subsidence:-Excessive extraction of groundwater has caused land subsidence in numerous urban areas. As groundwater is depleted, the land sinks, creating additional low-lying areas that are vulnerable to waterlogging.

8) Lack of Integrated Urban Water Management-There’s a lack of coordination between various departments handling water supply, sewage, and stormwater drainage. This results in fragmented approach to water management. For ex- the administration is fragmented among at least 11 different agencies responsible for roads and drains in Delhi.

9) Siltation of Rivers and Water Bodies-The National Institute of Hydrology reports significant siltation in urban water bodies and rivers. This leads to reduced water holding capacity of lakes and rivers and impaired natural drainage systems.

9) High Population Density-Rapid urbanization and population growth lead to more paved surfaces like pavements, roads, and buildings. This reduces natural water absorption and increases surface runoff, worsening waterlogging during heavy rains because water can’t soak into impermeable surfaces.

What is the impact of urban flooding?

1) Loss of Lives and Injuries-.People can become trapped or swept away in submerged areas, resulting in fatalities and injuries.

2) Damage to Infrastructure: It can lead to widespread damage to buildings, roads, bridges, and other infrastructure. Homes, businesses, and public facilities may be flooded or destroyed, causing substantial financial losses for individuals, communities, and the government

3) Displacement of Vulnerable Population:Poor individuals may be compelled to vacate their house and seek temporary shelter, encountering difficulties in finding appropriate accommodation and enduring the loss of personal belongings.

4) Disruption of Vital Services:It can cause disruptions to essential services like electricity, water supply, and communication networks. This can aggravate hardships for affected communities and impede rescue and relief efforts.

5) Waterborne Diseases: It can increase the risk of waterborne diseases such as cholera, typhoid, and diarrhoea.

6) Economic Consequences:Businesses may experience financial losses from property damage and operational interruptions. Furthermore, the government bears expenses for rescue and relief operations, infrastructure repairs, and rehabilitation.

8) Mental and Psychological Stress-The experience of trauma, anxiety, stress, and losing personal belongings can impact the mental health of those affected.

What steps have been taken by Indian government and various state government to address the issue of urban flooding?

1) National Level Initiatives:

A) National Urban Flooding Programme-It aims to establish a holistic approach to urban flood management, encompassing guidelines for flood risk assessment and strategies for mitigation.

B) Smart Cities Mission-It integrates urban flood management as a pivotal component and advocates for the adoption of technology in real-time flood  monitoring and early warning systems.

C) Atal Mission for Rejuvenation and Urban Transformation (AMRUT)–It focusses on enhancing urban infrastructure, especially stormwater drainage systems, and allocates funds for upgrading and expanding drainage networks in selected cities.

D) National Disaster Management Authority (NDMA)- It has issued comprehensive guidelines on urban flooding that provide a framework for flood risk assessment and management.

2) State and City-level Initiatives:

A) Mumbai-The implementation of the BRIMSTOWAD (Brihanmumbai Storm Water Disposal System) project includes upgrading existing pumping stations and installing new ones, as well as conducting desilting of major nullahs (drains) before the monsoon season.

B) Chennai-C-FLOWS, an acronym for Chennai FLOod Warning System, is a flood warning system customised for use in Chennai.The six-module ensemble can predict flooding due to heavy rainfall, sea-level rise and increase in water levels of the three rivers — Cooum, Adyar and Kosasthalaiyar — that traverse the city.

C) Kolkata-:The Kolkata Environmental Improvement Project (KEIP) involves upgrading sewerage and drainage systems, installing new pumping stations, and dredging and renovating canals.

D) Bengaluru :Efforts include rejuvenating lakes and water bodies, implementing rain gardens and bioswales in specific areas, and undertaking initiatives to remove encroachments on stormwater drains.

E) Ahmedabad:Development of the Sabarmati Riverfront, which includes flood management measures.

What should be the wayforward?

1) Capacity Development of ULBs-There is a need to encourage staff to acquire new skills  by offering suitable incentives. State governments and ULBs should prioritize rebuilding the foundational structure of local government institutions, ensuring adequate staffing at the ULB level and establishing training facilities.

2) Water-Sensitive Urban Design and Planning-Water-sensitive urban design and planning techniques are most important.These methods consider land features, surface types (whether they absorb water or not), natural water flow, and have minimal environmental impact. City master plans should include mandatory assessments of vulnerabilities and risks.

3) Adopting Scientific Management Measures– Initiatives should begin with mapping areas vulnerable to waterlogging. Hydraulic and hydrological models should  analyze flood patterns, with results incorporated into urban master plans.

4) Decentralized Stormwater Management: Promoting decentralized stormwater management techniques such as rainwater harvesting, bioswales, and retention ponds can mitigate waterlogging at the local level.

5) Smart Drainage Systems: Utilizing advanced technology like sensor-based drainage systems that can detect water levels and regulate flow in real-time can improve the efficiency of urban drainage networks.
For ex-airborne laser terrain mapping (ALTM) is an active remote sensing technology that employs light detection and ranging to measure topography at a high spatial resolution over large areas. It can serve as a crucial tool in urban planning and developing flood riskmaps.

6) Synergistic Approach-There is a need for improved coordination between various institutions especially between water resources and disaster management authorities for integrated and coordinated approach.

7) Engaging Grassroots Organizations -Engagement with grassroots organisations is necessary to promote awareness on holistic flood risk management. Participatory approach for early action coordination among stakeholders can help mitigate waterlogging issue.
For ex–Environmentalist Foundation of India (EFI), Chennai:-It has restored over 39 lakes in Chennai, significantly reducing waterlogging in surrounding areas.

8) Revival of Local Water Bodies-There is a need  to prioritize the protection and restoration of traditional local water bodies in urban areas. These water bodies would be integrated into urban blue-green infrastructure to enhance water levels and quality
For ex–Biome Environmental Trust, Bengaluru-They have led in decentralized wastewater treatment and rainwater harvesting. Their “A Million Recharge Wells” campaign has raised groundwater levels and lessened flooding.

9) Green Infrastructure: Implementing green roofs, rain gardens, bioswales, permeable pavements, and urban green spaces can absorb rainwater and minimize surface runoff, thereby reducing strain on drainage systems.

10) Nature-Based Solutions: Implementing nature-based solutions such as restoration of natural wetlands, creation of urban forests, and revitalization of water bodies can enhance natural water absorption and reduce waterlogging.