Unplanned real estate development in cities have led to increased flood risks and deteriorating infrastructure
Representative photo: iStock. Unplanned development and urbanisation have been fuelling catastrophes in metropolitan cities like Bengaluru. Real estate development has been a key driver of Bengaluru’s economic growth. The sector, however, has mushroomed at the cost of compromised infrastructure, the real estate consultancy Knight Frank has noted in its report on Bengaluru’s urban flooding, released on May 31, 2023.
As cities like Delhi, Mumbai, Chennai, Calcutta, Bangalore, Hyderabad and others became centres of commerce and rapid urbanisation, India underwent a significant transformation. Urban population growth necessitated more durable infrastructure, including roads, housing, etc. Unplanned urbanisation has brought about significant challenges, including urban flooding due to inadequate stormwater management.
Also read: Bengaluru floods: City’s stormwater drains are not good enough & government has known it for long
Bengaluru has experienced rapid economic growth and population expansion in recent years. The city’s development in IT, biotechnology, education and industrial sectors has led to significant employment opportunities, contributing over 36 per cent to Karnataka’s Gross Domestic Product.
However, this unprecedented growth has strained the city’s ecosystem, particularly its stormwater drainage system. Unplanned real estate development and the changing climate have increased flood risks and deteriorated infrastructure. Every year, Bengaluru is highly susceptible to flooding between September and October, bringing life to a halt and causing a substantial economic loss to the city.
Bengaluru incurred a loss of Rs 337 crore due to heavy rains in September last year, according to the municipal authorities. The rains damaged 397 km of the city area. It is pertinent to remodel the stormwater infrastructure of Bengaluru to ensure sustainability.
A graph representing the city’s rainfall data over the last decade. Source: WRIS.
The city receives an average annual rainfall of 900-1,000 mm. A 2021 CAG report of the Karnataka government showed the performance audit of stormwater management in the city.
“Bangalore city witnessed large-scale encroachments on lakes and drains, depletion of natural drainage systems, changes in land use, reduced vegetation cover and loss of interconnectivity between water bodies and increased stormwater runoff,” the report pointed out.
Of the 1,452 water bodies in the early 1800s, only 194 remained in 2016 in the same area due to the lack of a robust stormwater management policy.
The city is located on the Deccan Plateau at an altitude of 920 metres, on the ridge along three valleys: Koramangala-Challaghatta, Hebbal and Vrishabhavathi. These valleys used to be interconnected through a cascading drainage system, with primary drains channelling water from one lake to another. However, unplanned urbanisation has destroyed nearly 50 per cent of the city’s stormwater drainage infrastructure.
Also read: Bengaluru, Lucknow flooding: What do we mean by water-sensitive cities?
“One of the major reasons of urban flooding is that roads are cut across the slope, making sheet flow difficult,” said Vishwanath S, advisor, Biome Environmental Trust, Bangalore.
The city has seen the construction of about 213 million square feet of Grade A office space, generating millions of white-collar jobs. However, this development has disrupted the natural valley system and damaged the interconnectivity of lakes within the city. One reason for this catastrophe is the inappropriate connectivity of roads and drainage systems. The concretisation of roads, pavements and paths creates infiltration problems. It is very important to ensure the filtration of rainwater to recharge aquifers, he added.
The city’s topography, coupled with inadequate infrastructure, has resulted in flooding in different parts in recent years. Carrying drainage water to treatment systems requires additional infrastructure and resources, he added.
To accommodate the city’s population growth and economic development, Bengaluru requires a comprehensive stormwater drainage master plan. The current drain length of 842 kilometres needs to be expanded by approximately 658 kilometres to ensure efficient stormwater management, the report noted.
It estimated the capital expenditure for constructing new primary drains and rehabilitating existing drains to be around Rs 2,800 crore. Additionally, ongoing maintenance and operation costs are necessary to sustain the infrastructure.
A toolkit released by Delhi-based non-profit Centre for Science and Environment said stormwater management should be an integrated part of a water-sensitive urban development plan. “One possible solution is to adopt nature-based solutions, such as ‘sponge city’ developments, to manage urban flooding,” it noted. The initiative was introduced by China in 2014 to integrate green spaces and wetlands with conventional infrastructure to control flooding, improve water quality and enhance ecological environments.
Bangalore is just one example for urban flooding. “There is a need for urban areas to improve water management. Urban water harvesting offers a solution to deal with meeting water demand as well as reducing the intensity of urban flooding. Thus, the urbanisation process and the hydraulic insufficiency of drainage systems are two of the most common causes of urban flooding,” noted a study by the Indian Institute of Science, Bangalore.
Initiatives by National Capital Region Planning Board also mentioned the significance of stormwater drain infrastructure. Delhi Development Authority has also taken up initiatives to prepare plans on stormwater drain management and incorporate them at the city level.
Remodelling stormwater infrastructure is crucial for any city’s sustainable development. The same kind of studies and planning is required for cities like Delhi and Chennai, where incidents of urban flooding are recurring, especially during monsoons with an annual rainfall of 790 mm and 1400 mm, respectively.
The increasing population in the cities creates pressure on infrastructure. Unplanned real estate development and climate change have strained the city’s drainage system, leading to increased flood risks.
By implementing a comprehensive master plan, incorporating nature-based solutions and exploring innovative financing options, cities can enhance their stormwater infrastructure and ensure a resilient and sustainable future. Such investments in infrastructure will not only protect the cities from flooding but also contribute to its economic growth and sustainable water management.
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