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Google Street View helps manage urban ecosystem

A canopy image taken from Google Streetview.Kannal Achuthan

A canopy image taken from Google Streetview.Kannal Achuthan  

Scientists have used over 100,000 images extracted from Google Street View to map and quantify how street trees regulate urban ecosystems in megacities like Delhi and Shanghai.

While it was generally accepted that trees and plants helped in regulating urban ecosystems, until now researchers had very little data to to quantify its extent.

Most of the research has been conducted in the temperate zones of Europe and North America, but little is known about how trees contribute to urban ecosystems in tropical regions.

Researchers in the Future Cities Laboratory at the Singapore-ETH Centre, a research outpost of ETH Zurich, developed a method to map and quantify how street trees regulate ecosystem services. Scientists analysed hemispherical photographs using an algorithm to quantify the proportion of green canopy coverage at 50 metre intervals across more than 80% of Singapore’s road network.

High spatial resolution

Google Street View’s technology allowed researchers to tap into a standard dataset of panoramic photographs and streetscapes that use a global positioning system (GPS) to map images to specific locations.

The high spatial resolution of the images allowed researchers to estimate the amount of solar radiation that reaches the Earth’s surface.

“In addition to cooling urban micro climates, these trees, which are integrated within dense urban street networks, also reduce the risk of flash flooding and helps in cleaning the air,” said Peter Edwards, Principal Investigator at the Future Cities Laboratory.

Researchers said that increasing the cover of the street tree canopy could reduce ground surface and air temperatures on Singapore’s streets.

“Providing trees to help cool the environment is important in tropical cities like Singapore, which suffers heavily from the urban heat island effect,” said Dan Richards, from the Future Cities Laboratory.

This new and relatively inexpensive method of rapidly estimating the amount of shade provided by street trees could help urban planners to identify areas of a city with low shade and prioritise the planting of new trees, researchers said.

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