Urban Sprawl in India is Causing Floods: Is Revisiting Stormwater Management Systems the Potential Solution?

India’s major cities experience floods due to unpredictable monsoon patterns along with multiple reasons such as poor urban planning, convoluted governance, inadequate drainage,  and population growth. However, two primary deficiencies of our cities must be explored, namely, urban sprawl and inadequate storm water management systems. While the other factors also aggravate flooding, articulating the nature of these two issues and a potential cure for the problem is the need of the hour.

The Trying Pattern of Indian Urbanisation

India’s economic shift from agriculture to urban services led to rural-to-urban migration. The lack of reliable income from farming drove people to seek better opportunities in big cities, leading to overcrowding and the rise of informal settlements.

This led  to ‘Horizontal Urban Sprawl’ in India, a phenomenon wherein, because of economic activity, the periphery of cities experience uncontrolled growth. To prevent such uncontrolled growth, the government adopted a conservative land-use policy and limited Floor Space Index. However, segregated land use along the newly developing areas and mixed land use in the older parts of the city emerged as urbanisation patterns which challenged the drainage and stormwater systems in India.

The Governance and Planning Conundrum

The government recognised the need to renovate the distribution, ownership and tenure of land policy to control excessive land ownership among the socially and economically powerful.  While the intention of this policy was noble, the result was fragmentation of land. In urban areas also, although a major share of land parcels is governed and administered by the state governments, land use is highly deficient due to poor land ownership records and fragmentation of land. This poses a challenge to efficient spatial planning.

Given the federal structure of our polity, planning and governance of India’s major cities must be overseen as per their respective masterplans. The 74^th Amendment Act (1992), in its item 18 of the 12^th schedule, distinguishes between land-use planning and urban planning. Many cities engage in urban planning to respond to the infrastructure needs of the populations but place land-use/spatial planning on the backburner.

NITI Aayog also outlined that implementing the 74^th Amendment Act wholeheartedly and employing subject matter experts in the planning committees would result in better urban planning. However, there is approximately a 42% vacancy of 3,945 sanctioned positions in town planning committees across India. To make up for this vacancy,  professionals with non-planning degrees are being hired to fill the vacant positions.  

Effect of Development Projects on Stormwater Management Systems

European road construction models in the 18^th-19^th century like the Tresaguet, Metcalf and Macadam situated their drain holes along roads to divert rainwater and stormwater from roads and not from catchment areas. After independence, India followed a similar road construction model. Consequently, sewage networks in the core clusters of a city are burdened with sewage water and flood water. In the low-lying areas, squatters, development projects and housing structures are environmentally burdensome.

Evidently, Mumbai prioritised urban development, and exploited  about 40% its mangroves which was nature’s flood proof system; Delhi offered the Yamuna’s floodplains and its wetlands to construction projects and encroachers, disturbing the natural flow of the river; Chennai sacrificed its lakes and wetlands as proved by the VBR Menon Vs State of Tamil Nadu case which revealed that there was a decrease of around 645 hectares of 1,130 area of 19 main lakes and the exploitation of its five wetlands. Such an urbanisation pattern is observed across all major cities. The floods in Mumbai (2005), Chennai (2015), Hyderabad (2020), and the 2024 floods in several cities across India are a testimony to this.

The draft National Land Utilisation Policy of the Department of Land Resources also noted that, the fragmented planning and implementation of water resource projects undermines optimal resource utilisation, environmental sustainability, and overall benefit to people. Natural water bodies and drainage systems are being encroached upon and diverted for other uses. Between 2018-2023, across Madhya Pradesh, Arunachal Pradesh, Odisha and Gujarat 90,001.5 hectares of forest land has been approved for road or mining projects. Given that stormwater runoff is already accelerating due to poor road structures, endangering existing green cover is concerning.

Detrimental Sewage Systems are Stunting Stormwater Networks

The IRC: SP: 50: 1999 guidelines of urban drainage focus on building a channel of vast drainage channels to divert stormwater from road surfaces to water bodies located in the outskirts or outside city limits. These guidelines were amended in 2013 to better suit current rainfall patterns, which suggested utilising green spaces and traffic islands to absorb stormwater and adjust the runoff volume. However, the current drainage networks in cities are still in accordance with the 1999 guidelines. Rectifying the existing drainage system along these crucial water receiving points will prove to be challenging as the focal points are densely populated. To address this issue, the concerned authorities (Urban Local Bodies, Public Works Departments, Housing Boards) need to ensure coordination which is currently lacking.

At present, the stormwater system network covers around 20% of road network and catchment areas. The CPCB revealed that India is equipped with Sewage Treatment Plant (STP) capacity of 31,841 MLD which has an operational capacity of 26,869 MD. The IRC in its 2013 IRC: SP: 050 guidelines noted that replacing paved roads and lined drains with gutter systems, lined channels and stormwater drains has reduced permeability, resulting in rapid drainage, increased runoff volume and peak discharge. This has reduced groundwater levels and increased waterlogging in cities.

India disposes around 70,000 million litres of wastewater per day of which 61% of sewage is discharged by cities. Of this, only 28% is treated and the rest discharged. As stormwater and sewage water ultimately end up in rivers, groundwater depletion is also on the rise.

The Potential Strategy

Cities were built to handle floods once a year or once in every two years (rainfall of only about 12 mm/hr – 20 mm/hr). However, big cities now receive over 50 mm per hour on average as seen in Mumbai, Kolkata, Bhubaneshwar, 30 other state capitals and union territories. To address the rising intensity of rainfall, state governments need to develop blue-green-grey infrastructure to alleviate urban floods and correct the consequences of urban sprawl.

AMRUT 2.0 has envisioned this for cities, which in 2024 established 37,49,467 sewage connections and 2,411 parks. However the central government must devise a strategy to supplement local bodies efforts in desilting and unclogging sewerage on the eve of monsoon such that runoff is accelerated, as envisioned by the Manual on Stormwater Drainage Systems by the CPHEEO. For enhanced decision-making, a unified Management Information System dashboard displaying crucial stormwater management datapoints of Tier 1 cities must be maintained. ULBs and parastatals must maintain vigilance over low-lying areas. Private real estate developers violating Building Code Regulations must be penalised as well.

As anthropogenic activities deter natural ecosystem’s manner of dealing with rainwater, state governments must redesign urban drainage/stormwater networks to effectively handle current rainfall patterns and mitigate urban flooding.

DISCLAIMER : The views expressed in this blog/article are author’s personal.