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December 19, 2023Urban Flooding in India: A Consequence of Poor Implementation, Not Inadequacy of Guidelines
Policymakers and planners should recognise that minimising runoff from built-up areas onto roads is the best method to decrease city waterlogging.
When we talk about the monsoon today, the first image that typically comes to mind is waterlogged urban roads. Flooded streets have become a common sight in urban India, leading to increased demands from the general public for additional grey infrastructure, such as concrete drainage systems. Meanwhile, experts in the field of urban flooding attribute this issue to the repercussions of climate change, advocating significant alterations in urban planning practises, including the adoption of “sponge cities,” which can entail substantial capital investments. While the reality of climate change is undeniable, this article aims to shed light on the shortcomings of our drainage planning systems and policymaking.
In the road construction models of the 18th century, like the Tresaguet road construction model (France, 1764), the Metcalf road construction model (France, 1717-1810) or Macadam construction (in England), the practise of constructing drainage systems alongside roadways was for the removal of water from pavements, safeguarding roads from water-related damage. The idea was to collect the stormwater from the roadways and was not focused on gathering water from the entire catchment area. When the concept of concrete drainage systems was adopted in India after independence, the availability of open spaces in our urban areas facilitated rapid post-rainwater drainage. However, as we now reside in concrete jungles, the permeability of our urban landscapes has significantly decreased, leading to the convergence of water from entire catchment areas towards the road-based drainage systems – the real reason for water logging.
Like other states, Kerala’s building rules (Kerala Panchayath Building Rules 2019 and Kerala Municipal Building Rules 2019) mandated the need for rainwater harvesting systems in all new buildings (except the hazardous occupancy buildings), but were later amended in 2020 to make exceptions for housing units in a plot of less than 5 cents and/or having built-up area upto 300 sq.m. As the average floor area in Kerala is 90.1 sq.m, according to the Multiple Indicator Survey in India (NSSO report), the amendment exempts a major share of housing units from the rule. While the rule mandates rainwater harvesting systems for new buildings, there are no retrofitting programmes for existing buildings to minimise the stormwater outflow into the roads.
Another significant challenge lies in the design of road drainages. While stormwater drainage systems in cities conform to the specifications outlined in IRC:SP:050 published by the Indian Roads Congress, it is important to note that many drainage systems still adhere to earlier versions of this code. The outdated approach (in IRC:SP:50-1999) primarily focuses on channelling stormwater from road surfaces to water bodies located at the periphery or beyond city limits, necessitating the construction of extensive drainage channels. The revised version of the Code (IRC:SP:50-2013) advocates managing stormwater through the utilisation of open spaces and traffic islands. However, the major challenge lies in the retrofitting of green spaces and traffic islands, which are often elevated compared to road surfaces, hindering effective water drainage. This design feature can be traced back to the specifications in the IRC:SP:50-1999, which mandated that curbs and traffic islands adjacent to roads be set at higher levels to prevent water ingress. Even the construction of flyovers adheres to antiquated drainage practises. The older version of the Code stipulates the collection of water from flyovers, which is then connected to manholes to drain water into the city’s drainage system. This obsolete approach has endured in many cities, leading to the buildup of substantial volumes of stormwater during every rain shower.
The 2013 revision of IRC:SP:050 provides a comprehensive framework for responsible stormwater management, with an emphasis on rainwater harvesting techniques. By embracing modern drainage practises, incorporating rainwater harvesting, and reassessing outdated design standards, the revised code tries to transform cities into more resilient and sustainable environments that effectively harness the potential of rainwater as a valuable resource. It also insists on the design of traffic islands and curbs to include the incorporation of planters and tree trenches to facilitate the ground-level drainage of stormwater, thereby reducing runoff volumes on roads. According to the revised code, the downpipes collecting water from flyovers should be connected to rainwater harvesting systems, with excess water flowing into the city’s drainage system.
The presence of multiple governing agencies responsible for the development of urban space in our cities is also causing difficulty in developing an integrated drainage system. Each of these agencies prepares its own plans, such as smart city plans, development area plans, NMT plans in the Metro corridor, and more. These plans often prioritise the development of drainage systems separately, without considering their interrelation. The redesign of these drainage systems, which may not align with the revised code (IRC:SP:50-2013), becomes a complex endeavour as a result.
To address the pressing issue of urban waterlogging, we must adopt a more sustainable and forward-thinking approach to urban/rural planning and drainage systems. Policymakers and planners should realise that the most effective way to reduce waterlogging in our cities is by reducing the quantity of stormwater flowing from built-up areas into the roads. Water should flow from one place to another, mimicking a natural drainage system; thus, allowing all the rainwater to be converted into stormwater and then routing it into the drainage system is not the ideal solution. Stormwater management in a city should start with individual houses; each building/plot should constitute a rainwater harvesting system, regardless of the plot’s scale. Retrofitting programmes are to be hosted for the existing buildings by providing incentives for incorporating a rainwater harvesting system.
The reconstruction of existing drainages, traffic islands and open spaces along the roadways, aligning with the principles outlined in IRC:SP:50-2013 is necessary. The effectiveness of the practises endorsed in the revised code can only be analysed through practical implementation. A change is required at an administrative level too, aiming to improve transparency among government bodies and ensure that officials are well-versed in the importance of complying with updated codes while designing physical infrastructure.
(This article is first published on Deccan Herald)
Views expressed by the author are personal and need not reflect or represent the views of the Centre for Public Policy Research.
Nikhil Ali is an Associate, Research at the Centre for Public Policy Research. He completed his graduation in Civil Engineering from Sree Narayana College of Engineering and is a seasoned Civil Engineer with working experience at Tata Realty and Infrastructure Ltd. With a passion for urban planning, he acquired his master's degree in Urban Planning from Hindustan Institute of Technology and Science, Chennai. His expertise lies in Urban Mobility, land use planning/analysis, and water-sensitive planning.
