New global flood monitoring system saves lives

A new type of image from NASA’s Terra spacecraft is helping the UN plan emergency food supplies for the victims of flooding in Southeast Asia (see related story).


The United Nations World Food Programme is using new composite surface images produced at Dartmouth Flood Observatory in New Hampshire in order to pinpoint the worst-hit areas of the flooding.

The frequent heavy cloud cover over Southeast Asia makes it difficult to regularly see the surface and flooded areas, says Brakenridge. To overcome this problem, eight MODIS images from consecutive days are blended together to produce one image that combines all the cloud-free views of the surface. The system provides an insight into how much floods rise or fall nearly every week.

“MODIS has made an enormous difference in our flood mapping,” said Robert Brakenridge of Dartmouth College. “MODIS can image most of the world every day and it views a very wide area.” According to NASA, the images are much more detailed than other readily available wide-area images.

“The MODIS maps are proving really useful to us,” said Mahadevan Ramachandran, the United Nations World Food Programme regional vulnerability analysis and mapping officer in Phnom Penh, Cambodia. “In areas like Cambodia and Laos where there are weak data collection systems on the ground, the MODIS data will be our first-hand information to identify the areas we need to visit and assess for ourselves.”

Ramachandran uses the new MODIS maps to compare with 1999 flood maps to pinpoint those hardest hit by the current flooding. “We overlay the MODIS maps with maps of crop production, poverty level, and land cover and land use derived from Lansat images to design our food aid relief efforts,” explained Ramachandran.

The Dartmouth Flood Observatory uses satellite images from the Advanced Very High Resolution Radiometer on National Oceanic and Atmospheric Administration satellites, the Canadian Radarsat, NASA’s Landsat 7, and now Terra.

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