Lost lakes and trees have led to green disaster in Bengaluru

Bengaluru is facing a monumental environmental crisis, and the only way to save it is to revive its lost lakes and trees – which earlier nourished the city and its people.

According to the Centre for Ecological Sciences (CES) of the Indian Institute of Science, Bengaluru has lost its green cover by a whopping 66 per cent and water bodies by 74 per cent.

The city’s build-up area has also seen a mammoth growth of 584 per cent, making Bengaluru – India’s IT capital -- a concrete jungle.

Paved surfaces

"The increase in paved surfaces and reduction in green spaces have contributed to the urban heat island effect in Bengaluru," said professor TV Ramachandra, coordinator of energy and wetlands research group at CES.

Experts warn that the situation will get worse at this rate.

By 2038, CES predicts that forests will be reduced to 0.65 per cent (as per last census in 2022, it is 3.32 per cent).

Heat sinks

Bengaluru city will be choked with paved surfaces (more than 98 per cent) and 69.90 per cent (from 55.71 per cent in 2022) in Bengaluru Urban will be paved areas by 2038, said a study by the CES.

Ramachandra says that decline in heat sinks (water bodies and green cover) has a negative impact on Bengaluru’s microclimate, evident from the reduced cooling effect and increase in land surface temperature.

"The urban heat island effect would enhance the ambient temperature and humidity levels, resulting in heat stress and heat-related illnesses," he added.

Early settlers

Bengaluru got its famed “mild weather” thanks to early settlers who understood the pulse of nature, said Harini Nagendra, professor of ecology at Azim Premji University.

The early settlers had a ‘three-dimensional sense’ of the landscape. "For instance, when constructing a new lake, the ‘plan’ would include the wells below and the trees above," Nagendra told PTI.

Along with numerous water bodies, the early settlers also put in place what were called ‘gundathopes’ or orchards or wood lots.

Trees aplenty

According to Nagendra, "Locals say rulers Hyder Ali and Tippu Sultan started the trend, which was later adopted by the British. Around every village there were three to four of these gundathopes where people would plant trees – they could be jackfruit or mango or other shade trees."

“They became gathering places for people. They were also ecological resources, making the climate cool, offsetting the heat effects."

"The open wells and lakes that were part of these gundathopes provided water to people, especially during summer because Bengaluru has always been this unusual semi-arid city, which doesn't get a lot of rainfalls that it needed to harvest every drop of water that it gets," added Nagendra.

Trees and temperature

Nagendra said that research by her team in different parts of Bengaluru has shown the relation between trees and air temperature.

"We found that trees reduce suspended particulate matter and soot in the air. But very importantly, they also cool the city. This is critical as we have lost wetlands and lakes to concrete,” she said.

“Concrete absorbs heat during the day and retains it at night. So, the next day is even hotter as the heat has not been released back to the atmosphere."

Green cover

In the process, while it could be around 65 degrees Celsius on the tar road surface, it would be only around 30 to 35 degrees Celsius under the tree-shaded surface.

Ramachandra said that Bengaluru has 14,78,412 trees, far short of the basic requirement.

“Going by population, in Bengaluru, we have only 17 trees per 100 persons. If we calculate as per carbon-dioxide released by us, we will need seven to eight trees per person to combat deficiency in oxygen," he said.