There’s an interesting piece in New Scientist today about how non-governmental organization Medecins Sans Frontières (MSF) is exploring the potential of using satellite images to estimate population counts for international medical and disaster relief efforts.
Currently, non-governmental organizations delivering humanitarian aid to war-torn areas, locations gripped by famine or regions battling epidemics rely on the “quadrat” approach to estimate population size. Using this method, a sample of individual households are surveyed and the data are used in calculating town or refugee camp populations. The process requires an ample number of samplers and careful post-survey analysis, which tends to make it slow.
So MSF partnered with London School of Hygiene and Tropical Medicine researcher Chris Grundy and colleagues to develop a way to use satellite images to speed up the population count process and tested it for a project in Am Timan in Chad. Andy Coghlan writes:
Preliminary results presented last week in London at the annual research meeting of MSF revealed that the satellite method matched the quadrat method for accuracy. Also, it took about half the time to deliver an answer, although Grundy says that with refinement it has the potential to be much faster.
Surveyors … still had to visit households in Am Timan to estimate how many people typically lived in each kind of building, but they could then make a city-wide estimate by counting the total number of each type of dwelling in the satellite image, either through a computer automated analysis or by manual counting.
The quadrat method, which required sampling visits to 1160 dwellings, gave a population of 49,722. The satellite technique, which required sampling visits to only 348 dwellings, gave estimates of 46,625 for the manual and 45,400 for the automated method.
“These results are very good, and there’s no doubt they’d be good enough for what MSF wants to do,” says Grundy. But the team hopes to make it faster still, potentially eliminating the need to sample dwellings first.
Researchers are continuing to test the satellite method at 11 global refugee camps.