Satellite can spot razed villages in Darfur; Free imaging data could rapidly pinpoint some human-rights violations.March 12, 2008 at 10:40 am | Posted in Remote Sensing Law Current Events | Leave a comment
by Joanne Irene Gabrynowicz with the blog faculty
Satellite can spot razed villages in Darfur-Free imaging data could rapidly pinpoint some human-rights violations.
Human-rights organizations may soon be able to use free satellite technology to spot evidence of abuses in Darfur and elsewhere. Villages that have been destroyed during conflicts or ethnic cleansing can be spotted from space by satellites, says Erik Prins, a Danish remote-sensing consultant. The low-resolution images, from the Landsat satellite, reveal subtle changes in the albedo, or reflectivity, of towns and villages that have been burned to the ground. Prins first began studying satellite data of Darfur at the request of the human-rights advocacy group Amnesty International in 2004 — a year after the start of the conflict, which has killed more than 300,000 people and displaced 2.3 million refugees.
His latest research, published in the International Journal of Remote Sensing, validates the results of his preliminary study for Amnesty2, and shows that the albedo method seems to be highly reliable. With a resolution of 30 metres, Landsat does not offer high-definition images, but even at this resolution the characteristic structure of villages in Darfur can be identified easily by a trained eye. Burnt villages reflect less light, and this reduced albedo is reliable enough to be detected by software analysis of Landsat data.
Amnesty commissioned the initial study to use satellite imagery – taken in March 2003 and May 2004 for a 32,000-square-kilometre zone of West Darfur — to try to verify eye-witness accounts, from refugees fleeing the region, of concealed mass attacks on civilians.
Independent verification on the ground was impossible, as Darfur was out-of-bounds to the media and to humanitarian groups. It was estimated that 44% of villages in the region had been destroyed over the course of the previous year.
Prins set out to validate the albedo method by comparing a sample of his initial results — covering 352 villages — with high-resolution satellite images published since by the United States Agency for International Development’s Humanitarian Information Unit, Google Earth, and Amnesty International.
Around half of the 352 villages showed detectably reduced albedo in 2004 compared with 2003, and the comparison with Google Earth images showed that this finding was 90% accurate. Prins suggests that the Landsat method could be a quick and cheap way to monitor large areas.
Given that Landsat images are freely available, the historical archive could “reveal a lot”, says Prins. It could also be used to put together a full picture of the destruction that has taken place in Darfur, he suggests — no comprehensive map of burnt villages in Darfur is yet available.