To Have Cooler Nights For Its Denizens, Ahmedabad Needs To Revisit Its Heat Action Plan

Unlike most Ahmedabadis, Payal, a 20 year-old household maid, isn't too pleased with the Monsoon bringing in the much-needed rain. "My cooler won't work, it is still extremely humid now. It needs to rain three days straight for my house to turn cool," she said.

The haves and the have-nots perceive seasons differently and their sense of relief isn't the same either. 

Ahmedabad, the third fastest growing city in the world as per Forbes, crossed the 8-million population mark in 2020. It has moved on from being a laidback city of 35.47 lakh in 1990 to a bustling metropolis which is now the fifth most densely inhabited in the country and 46th worldwide.

Like other big cities, Ahmedabad also has a heat stress problem. 

The Delhi-based Centre for Science and Environment (CSE) recently released its report tracking temperatures in six major cities over 23 years, from January 2001 to April 2024. 

The report's major finding has been that cities cannot cool down at night due to the Urban Heat Island (UHI) effect. The very same cities were however able to cool at night till the end of the 2000s.  

What Is the Urban Heat Island Effect?

UHI was first used to describe the difference in heat between days and nights in a city, as nights became warmer in the city when compared to the surrounding areas. As a result, the city residents felt no relief from the heat, even hours after sundown. 

The reason for cities not cooling at night is that buildings, roads, bridges, and pavements, which are bundles of concrete, end up trapping and absorbing heat as short wave radiations during the day. They let it all out at night as long wave radiations. 

The constant heat release during the day and night makes it harder for the cooling mechanism of the remaining vegetation to work effectively. 

The taller the building, the higher the chances of constant absorption and reflection of short wave radiations, making a pool of passed-on heat radiations deeper and inescapable. 

Reduction in green spaces in cities has led to lesser absorption of CO2, negating the cooling effect of trees.  

The side effects of the resultant UHI effect include heat stress, exhaustion, cardiovascular stress, heat stroke, respiratory diseases, etc. UHI conditions also lead to higher energy consumption as people switch on air conditioning to redress the heat problem, which in turn add more heat to the already boiling city. 

"(It) is necessary to develop a comprehensive heat management plan for urban centres. This is needed to implement emergency measures during heatwaves to health, and also to develop longer-term strategies to mitigate heat by increasing green areas and water bodies, improving thermal comfort in buildings, and reducing waste heat from vehicles, air conditioners, and industries," the report noted. 

Where Does Ahmedabad Stand On Heat Management? 

"Urbanisation exacerbates the Urban Heat Island effect, leading to increased temperatures, health risks, and higher energy consumption. Ahmedabad's water bodies also suffer from neglect due to rapid development and regulatory gaps," Bhavik A. Ramani, editor of the Environment Post, said.

IIT Roorkee and School of Technology, PDEU's joint spatio-temporal assessment research report notes the direct correlation between population growth and urban expanse. It says that for a rise in 1 lakh population, a built-up area of 3.9 square km is needed afresh to accommodate them.

The report demarcates the land use and land cover into four categories: vegetation, water body, built-up area, and bare land. The first two are self-explanatory but the findings in the last two categories are worrisome.

"The built-up area (of Ahmedabad) grew from 181.45 square km in 2000 to 276.46 square km in 2010 and 305.24 square km in 2019. During 1990-2019, the region's total built-up area more than doubled, showing 130 per cent growth."

The study noted the halving of open areas, bare plots, uncropped farmland, landfill areas, and other remaining land uses, with a per annum decrease of 17 per cent every year. The halving in open areas meant there is less space for rainwater to permeate into the ground and for vegetation to grow.

The report predicts that the built-up area in the city will increase from 305.24 square km in 2019 to 383 square km by 2030. This would come at the expense of open grounds, bare lands, etc which are expected to shrink further from 358 square km in 2019 to 271 square km. 

The report expects green cover to grow from 227 square km in 2019 to 234 square km in 2030. It adds, "no appreciable changes are expected in the size and locations of the city's water bodies. The city's population is expected to grow by 18.8 per cent, reaching 93.5 lakh in 2030."

The larger population, the report calculates, "shall require a 374.2 square km of built-up area (by 2030).” 

But despite all these and the promise of what lies ahead, the heat action plan for Ahmedabad has stuck to being just a mitigative plan and is far from being preventive. The heat action plan usually lists what the authorities need to do when heat waves begin. 

Given the growth potential of the city and the importance of the have-nots in that trajectory, the heat action plan for Ahmedabad could do with more changes. 

 

[To be concluded]