Vertical growth of cities

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Context:

Cities around the world, but especially in Asia, are growing upwards faster than they are spreading outwards, a new study published in Nature Cities has found.

Introduction

As cities become increasingly populated, the demand for space has also escalated rapidly. In response to the scarcity of land, tall buildings emerged as a solution as part of development for various Indian cities, optimising limited land resources.

Vertical Urbanism

• Vertical Urbanism is a concept that has emerged as a response to the challenges of urbanization and population growth. It refers to the development of high-rise buildings that can accommodate large numbers of people in a limited space.

Recent Findings

• A team of earth and urban scientists conducted a study examining more than 1,500 cities around the world from the 1990s to the 2010s.
• Using remote-sensing satellite data, they gathered information on cities’ vertical growth and their two-dimensional (2D) outward expansion.
• They utilized scatterometers—satellite-borne sensors that emit microwaves to the earth’s surface and collect the reflected data—to assess changes in the volume of city structures.

Vertical vs. Outward Urban Growth

• The study revealed that while the rate of 2D outward spread wasn’t increasing significantly, the volume of city structures was rapidly growing.
• The researchers identified a global trend of upward growth in cities, with East Asian cities, particularly in China, leading this trend.
• Cities with populations exceeding 10 million people exhibited more prominent vertical growth, a trend that became more pronounced in the 2010s.

Indian Cities' Urban Growth Patterns

• Indian cities did not show uniform upward growth.
• Only larger cities with populations over 5 million experienced either both upward and outward growth or just outward growth, primarily during the 2010s.
• Regulatory constraints in India, particularly regarding building heights, have limited the vertical growth of cities compared to East and Southeast Asia.
• For example, in Delhi, most growth was outward during the 1990s and 2000s, with some upward growth in the 2010s.
• Presently, approximately 250 tall buildings have been completed or are in progress across India.
• Mumbai, with a staggering population density of approximately 21,000 people per square kilometre, stands as the hub of tall buildings in India.

Implications of Vertical Growth

Advantages

• As more individuals migrate to cities, these areas continue to expand horizontally, resulting in increasing land use changes and adding to an increase in carbon emissions.
• Vertical growth presents an opportunity to mitigate these emissions by creating compact environments equipped with efficient mobility features.
• More space can be made available in city centres, where elevated offices and residences enable the ground floors and basements to be repurposed for shops and recreational amenities.
• Open spaces between clusters of high-rise buildings can be transformed into parks and public areas.
• In addition to their appeal to occupants, tall buildings also attract investors seeking high-net return properties, due to the potential for diversified tenant mixes.

Challenges

• Urban sprawl poses various challenges, including limited institutional capacities and fragmented government regulations.
• Vertical growth can increase population density, potentially housing more people if costs are reasonable.
• Taller buildings demand specialized resources and greater energy, contributing to the urban “heat island” effect and potentially affecting temperatures and rainfall in cities.

Regulatory Challenges

• In certain areas, such as New Delhi's "Lutyens bungalow zone," stringent regulations protect expensive central real estate, leading to taller buildings emerging in the outskirts, like Noida and Gurugram.
• Similar heritage or protected zones may exist in other South and Southeast Asian cities, making this situation incomparable to most North American cities.

The Need for Updated Urban Planning in India

• India appears to be following a trajectory similar to China's in terms of population growth and industrialization.
• However, most Indian cities and states, including Bengaluru, rely on outdated master plans that fail to account for transportation, energy, water resources, wastewater management, and solid waste.
• There is a pressing need to revise and rewrite master planning acts to incorporate progressive, enforceable laws that prioritize sustainability and liveability.

Way ahead

India needs trained planners to make decisions grounded in local contexts, considering the needs and aspirations of the population, as well as the objectives of sustainability and liveability. This approach is essential in the face of unprecedented climate change. Despite rapid urbanization, the majority of Indians still live in rural, dispersed settlements, which are more efficient and climate-resilient.

Source

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