After the disaster
January 22, 2010
A German research institution is assembling satellite images of disaster zones like Haiti and converting the data into digital maps that help international aid workers assess the damage and determine the best locations to build sanitation facilities and hospitals.
The maps are created by The Center for Satellite Based Crisis Information (ZKI), part of the German Aerospace Center's Remote Sensing Data Center in Cologne.
"Relief organizations use these images either in their headquarters or on the terrain to better organize themselves, and they can do this with the information we provide, which is initially a good road network," said ZKI senior researcher Olaf Kranz.
He added that ZKI also provides information on which buildings in the affected area are intact or have been destroyed.
Satellite images become useful maps
After a natural disaster occurs, like the recent earthquake and aftershocks in Haiti, ZKI researchers gather high-resolution satellite images which are so detailed that every object larger than 50 centimeters can be easily detected, Kranz said. Once the images are received, they are compared with pictures taken of the same location before the catastrophe.
"If you imagine an earthquake, sometimes there can be a building with a collapsed roof," said Kranz, "but in some cases you can't see that the roof has collapsed unless you compare the before and after."
But in the case of Haiti, the earthquake was so severe that the damage was very visible, added the researcher.
The satellite images are then visually interpreted into maps. Since the center does not have automatic algorithms, 25 employees do it manually on the computer and assemble the data into color-coded grid cells. The lighter yellow colors denote areas that were less destroyed in the disaster and the orange color means that more than 40 percent of the area was destroyed.
"This should be an indication for relief organizations where to focus their work," Kranz said. In addition, the maps are populated with red dots that the center calls potential gathering areas. These are points where the Red Cross and other organizations can build facilities or hospitals.
Cooperation with the Red Cross
For several years the center has been providing the Red Cross with such satellite data and maps, said Joachim Jaeger, the Berlin-based Red Cross logistics coordinator for Haiti.
"As soon as something happens, we immediately get in contact with ZKI and that means it's an emergency and it's a priority to create maps of an affected area," he said.
Once the maps are received, the Red Cross then sends out its delegates into the field with the information, and material for basic healthcare and mobile hospitals. Normally, those on the scene of a disaster have a limited view, Jaeger added, and this data allows the workers to see what's around them. The workers in the field then use the data to look for usable roads, measure the extent of the damage and identify the existing infrastructure.
In the case of the Haiti quake on January 12, Jaeger said, the Red Cross received the first maps within 18 to 24 hours of the event and used them to decide where to set up their facilities. Since then, ZKI researchers have constantly been sending updated maps.
According to Kranz, the project of converting satellite data into topographic maps began around 1999, and in 2002 and 2003 the center began producing maps especially for relief organizations working on the ground in disaster zones. But in comparison with other natural catastrophes, Haiti seems to be practically in a league of its own.
"We never saw large areas so totally destroyed like in the area of Port-au-Prince," he said, citing the 2004 Indian Ocean tsunami as the only comparable disaster.
Author: Alina Dain
Editor: Kate Bowen