A trip to the Pacific: mapping invisible environmental risks

The remote, low-lying coral atoll of Vaitupu in the Pacific Ocean could be helped by a satellite mapping project at MIT that seeks to expose environmental risks invisible to human eyes.

Vaitupu, with 1,600 inhabitants, is part of the tiny nation of Tuvalu, where the highest point is just 4 metres above sea level and so among the most vulnerable to sea level rise caused by climate change. The new environmental maps could help set a benchmark against which to monitor future changes in places like Tuvalu.

Normal maps show “streets and buildings – but they don’t really tell us much about the environment,” says Arlene Ducao of MIT, who is also co-principal with Ilias Koen of the DuKode Studio in Brooklyn, which runs the “Open-IR: Infrared for Everyone” project.

Blue pin = Vaitupu

Areas with buildings show up in pink

The maps use infrared, outside the visible spectrum, and filters that make hard-to-spot features – such as vegetation, soil, water or height above sea level – “pop” out from the background when translated into bright visible colours such as pink, blue or green.

water shows up as black or blue

Ducao and Koen obtained satellite maps of Tuvalu from U.S. Landsat satellite data for this News and Participatory Media item. Many experts say seas could rise a metre this century, as glaciers and ice caps melt and ocean waters expand – a creeping threat to Vaitupu’s population with projected erosion and salt contamination of cropland and fresh water supplies.

“The satellite data is available, it’s just difficult to use,” Ducao said in an interview in her office at MIT filled with a jumble of shelves with bits and pieces of metal, plastic, books and papers from other projects.

For Vaitupu, the images could help set a benchmark to track if the areas of vegetation or soil shrinks in coming years. Vaitupu is the largest of Tuvalu’s atolls and the site of the nation’s only secondary school.

Vegetation shows up as red

The main pilot project of OpenIR shows areas of Jakarta that are vulnerable to tsunamis – apart from the coastline it unexpectedly reveals some low-lying built-up areas inland to the east of the city that are also at high risk since there is little vegetation to slow any waves from the sea.

Another uses satellite data to peer into abandoned city-owned lots in New York to show which have vegetation and could be easily converted to parks.

Some places are hard to map than others. The main island of Tuvalu – Funafuti – is elusive on U.S. Landsat satellite data, apparently because it lies exactly on the far side of the planet from the north-south line set as the usual baseline for longitude in Greenwich, England.

“I think that island falls…just on the seam,” Koen said. Vaitupu and several other atolls north of Funafuti are visible.

Sitting in front of her computer, Ducao applies a new filter to the map of Jakarta. “The vegetation just pops,” she says of a sudden shift to bright-red tracts around the city Jakarta that highlight vegetation far better than a normal camera using visible light.

She switches on a different filter and all the impermeable surfaces – pavement, concrete buildings are shown in bright pink. “The downtown just pops,” she said. And an infrared filter well outside the visible spectrum reveals large areas around the city – apparently rice paddies.

Rice paddies are “not something you can see in true colour. And it doesn’t show up on street maps,” she said with a laugh. Google.org has some similar data but it is targeted at scientists and is hard to use.

Jakarta map shows tsunami risks -- the redder the more vulnerable

“Our initial audience is crisis responders,” she said.

The maps could also help, for instance, emergency relief teams deploy after a disaster such as Haiti’s earthquake – which could add data about faults where new tremors might occur or places where shelter was available.

In the longer term, it could help plan how to site buildings or agriculture out of harm’s way. Insurance companies might also be interested in the data for long-term premiums. Others from engineers to health workers could find uses.

“A lot of this stuff is done manually by crisis responders. Our value proposition is that a lot of this can be automated,” she said. Ducao and Koen were planning to create a web application where you could plot in latitude and longitude and get out a risk map.

The pilot pictures are based on free images by the Landsat satellite system, which ended in 2006. Ducao and Koen are now turning to data from modern satellites.

In New York, the project is helping an organization called 596 Acres, named after the area of city-owned land in Brooklyn that was going unused.

“The idea is to make abandoned public lots known to everyone so that people can make better use of these lots,” she said. Some lots are boarded off, while satellites can see if it comprises cement or buildings – harder to use immediately – or simply vegetation.

“If you can identify what is green it shows where you easily could develop a community garden, for instance,” said Koen. “This could be a very interesting civic use of the data.”

“NASA and government satellite agencies are not particularly interested in urban areas,” said Ducao. “Maybe if this project gains enough traction it could be taken over by agencies who have the computing power to take it over to make models, predictive modeling.”

“That would be cool.”


To access prototypes:

  Jakarta:  http://openir.media.mit.edu/jakarta
London:  http://openir.media.mit.edu/London
Tuvalu: http://openir.media.mit.edu/Tuvalu


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