Rise in built-up space increases Kochi temperature, says study

Kochi: Rapid development without addressing environment and ecological concerns has turned Kochi into small urban heat islands as land surface temperatures have gone up by 4-5C compared to its rural zones.
According to an urban climatic map modelled on Kochi city using data from two decades (2001-2021), places with high builtup areas had much higher temperatures due to urban heat island effect.The findings of the study ‘Evaluating the Impact of Urbanisation on Climate Change: A Case of Kochi City' was presented at Corp 2024 in Germany. It showed that some areas of Fort Kochi, Vyttila and the eastern regions require interventions with parks and green spaces. A re-positioning of buildings was needed to decrease heat gain, and the orientation of streets and buildings must be done to optimize ventilation.
"City masterplans don't have environmental and ecological elements which could balance the impact of infrastructure development. We looked at the builtup spaces in 2001, 2011 and 2021. It showed that builtup area has increased substantially and tree cover has reduced drastically," said Adinarayanane R, dean of planning and development, School of Planning and Architecture (SOPA), Govt of Andhra Pradesh, who led the study.
He said his institution has tied up with Kerala Institute of Local Administration (Kila) and is part of Kerala urban planning commission to evolve solutions for sustainable urban planning and development.
The study noted that the air temperatures in tree groves are 5C lower than on open land, irrigated agricultural fields are 3C lower than bare ground, and suburban areas with mature trees are 2-3C lower than new suburbs without trees, while grassy sports grounds are 1-2C cooler.
"In urban planning, it has become important to look at sustainable solutions. Urban heat islands can lead to more air-conditioning and cooling systems, thus adding to the greenhouse gas effect," he said. Urban planning policy for Kerala needs emphasis on green innovation in infrastructure development. It is better to plan local development so that rural people don't need to come to cities, thus reducing the city's burden too, he added.
While planning, high albedo pavements — which reflect more sunlight and absorb less heat and are made using concrete, asphalt and reflective coatings — should be considered. Permeable pavements allow water to pass through, reducing urban heat by absorbing less heat. Permeable pavements are usually made of pervious concrete, thus reducing flood risk, stormwater runoff and urban heat island effect. Vegetative covering on a roof, called "green roof", is another way to reduce urban heat. Cool roofing solutions made of highly reflective and emissive materials can bring down temperatures to 28-33C even during peak summer, the study suggested.