Remote Sensing Applied to War-Torn Regions
Many archaeologists spend their entire careers studying one historical site, getting to know it like they know their own house, says Jesse Casana, associate professor of anthropology at Dartmouth College in Hanover, N.H. That was the case for him and his colleagues working in the Middle East before the war affecting Iraq and Syria made boots-on-the-ground excavation too dangerous an approach.
“They were just suddenly forced to leave, never could go back,” Casana says. “I left a giant building full of my stuff and artifacts and equipment and a suitcase full of clothes. We just never went back.”
Thousands of miles and oceans away, archaeologists like Casana were suddenly unable to keep track of their sites and others in the wider war-torn area. But with the help of a collaborative agreement between the U.S. Department of State and the American Schools of Oriental Research (ASOR), launched in 2014, cultural heritage documentation is now possible without an archaeologist ever having to step foot on a site. Satellite imagery is being utilized to document archaeological sites, historical buildings, museums, mosques and other religious sites that have been damaged by war activity.
“In total, we have an inventory of over 12,000 items currently,” says Susan Penacho, project manager of geospatial initiatives for ASOR.
Cultural Heritage Initiative
ASOR is a professional organization comprised of Near Eastern and Middle Eastern specialists from a wide range of disciplines. The geospatial initiative Penacho oversees falls under the organization’s Cultural Heritage Initiative, which grew out of a U.S. Department of State grant. It is a collaborative effort to respond to the destruction of cultural heritage in Syria and northern Iraq, and consists of a team of scholars with professional connections to leading academic and cultural institutions in Syria, Iraq, the U.S., Canada, England, France, Germany, Lebanon and Jordan. Penacho says the group is largely made up of archaeologists who specialize in the Middle East.
Casana, an ASOR member and chair of its Damascus committee, has been closely involved in the Cultural Heritage Initiative. He says two years ago, before it was launched, there was no reliable information about what was going on inside of the area regarding cultural heritage. With archaeologists unable to visit the sites because of the war, they knew from reports of journalists and social media that there were probably a lot of very bad things happening to the sites, but the information ended there.
Remote Sensing for Site Tracking
Now that they have been granted access from the U.S. Department of State to DigitalGlobe satellite imagery, Penacho says new images are made available to them every day on an almost real-time basis. Casana says his experience with satellite imagery goes back years and that up-to-date data is crucial.
“The issue I faced in the beginning, two years ago, was that I had no access to sufficiently recent data. If you just looked up freely available Web mapping sources like Google Earth, there might be a couple of recent images, but most of it’s going to be from 2010, which doesn’t help if what you’re trying to do is monitor what’s happening now,” he says.
On a typical day, Penacho’s team is able to record up to a few hundred sites, keeping up with new satellite imagery as it comes out. She says the process they use is fairly basic and is not post-processing intense. They primarily use shape files with points and polygons to better understand the locations they are looking for. Then they download geo TIFFs from the DigitalGlobe server to be able to look at what is happening at an exact site. They are looking for change over time and Penacho says it has been possible to track that without having to do additional work on the satellite imagery.
The learning curve Penacho says she faced initially, despite her experience as an archaeologists specializing in the Middle East, was differentiating specific types of damage depicted in the satellite imagery. It involves identifying a looting pit, which can simply look like a dark hole or knowing the difference between a site that has been bulldozed and a site that has been illegally excavated. She says an important part in this training process is making sure analysts understand what specific sites and the wider landscape looked like before the conflict, and how it changed once the conflict started.
Devastation of War
With such a large span of damage done to such a large variety of sites, Penacho says the data collection the ASOR Cultural Heritage Initiative is making possible could be useful in helping the Syrian and Iraqi communities rebuild post war. “We can help illustrate where that money can be used,” she says.
In the past year, Penacho says a lot of damage has been done by military airstrikes and historical buildings are a common victim. She says it is sometimes possible to come to some conclusion as to the source of the damage by tracing back to who was in the area of the damaged site at the time of destruction, often with the help of reports of who dropped bombs in a specific area. However, she says it is hard to pinpoint who is behind each instance of site destruction, especially in cases of illegal excavation where, for example, looting at archaeological sites takes place, because of a lack of state control and no state entity behind the event to take responsibility for it as in the case of airstrikes.
There has been a lot of different kinds of damage done in the wake of conflict, Casana says, and while the kind that makes it onto the news is often intentional destruction performed by terrorist groups, the percentage of archaeological sites blown up by such groups is just a percentage of the total damage done.
“ISIS has intentionally damaged, of ancient archaeological sites, only a handful,” Casana says. “But in terms of ancient archaeological sites, the few big ones I know about, if you look at the archaeological site record itself we see something like, in Syria especially, north of 20 percent of the sites having been looted or damaged pretty severely through some other mechanism since the war. That’s an astronomical number if you consider that there’s tens of thousands of sites in Syria.”
The worst damage occurring because of the war is more related to the general happenings of the war itself than to any specific pact of terrorism, he says. He explains that during peace time in Syria, if you loot a site it is against the law and you could go to jail, but as soon as civil authority breaks down, looters go to town. There are also a lot of people who are desperate, he says, and looting is seen as a way to get a few extra bucks. In addition, many sites are located in strategic places and modern military field commanders also see them as strategically valuable places to occupy.
“The military will go on top of an archaeological site, bulldoze it, put giant tank bunkers there and really mess these places up. Those things are the biggest threat to the archaeological record in Syria right now,” Casana says.
Boots-on-the-Ground Geospatial Tech
As before the conflict ensued, upon its hopefully soon-to-come end, archaeologists will once again have in-person access to cultural heritage sites, which will call for the use of geospatial technology other than satellite imagery.
The work of archaeologists is a lot more strategic than commonly perceived, Casana points out, and it is all located in space, making any kind of spatial technology powerful in the discipline. “Excavation, which is what most people imagine archaeologists do, is extremely slow and time consuming and expensive, and probably most importantly, it’s destructive,” he says. “When you dig a hole in the ground, you can’t undo it and it can’t be re-dug again.”
Even in large-scale excavations, he says archaeologists only ever dig a very small percentage of a particular site, 10 percent at most. Most of the site is left intact, partly because they don’t want to destroy it and partly because to dig the entire site would be impossible. Geospatial technology offers a way to map the entirety of a site nondestructively so archaeologists like him can see how a site is laid out, allowing them to learn things about it that they could never learn by digging. It also offers a map of where everything is so that when digging is done, it is done efficiently — not in a random spot with fingers crossed that something important lies beneath. Archaeologists also utilize geospatial technology to conduct artifact-level analysis like 3D models.
Key geospatial technologies and approaches include magnetic radiometry, ground penetrating radar (GPR), electrical resistivity, drones, LiDAR and thermal imaging. Casana says geospatial technology is an extremely fundamental and transformative resource for archaeology as a discipline and that its integration will continue to grow with time.
“I think [geospatial aptitude] is really essential for the education of any modern archaeological student,” he says. “I think it’s becoming increasingly more widespread.”