New Map Chronicles Three Decades of Surface Mining in Central Appalachia

The data shows about 1.5 million acres of forest have been affected by surface and mountaintop mining since the 1970s

Christian Thomas, SkyTruth

Coal mining in Appalachia may bring to mind the archetypal soot-covered miner working deep underground. But in the last 30 years, a big percentage of coal mining has been done under the sun. Surface mining and a technique dubbed “mountaintop removal” have been controversial from the start for their use of explosives and heavy equipment to dig through soil and bedrock to get at coal seams from above. Yet information about where and how much of this mining has taken place has been hard to come by. Now, reports Yessenia Funes at Earther, researchers have created a new mapping tool to quantify the impacts of surface mining in Appalachia.

Researchers from Duke University and the environmental nonprofits SkyTruth and Appalachian Voices used new web-based mapping tools and Landsat satellite imagery to study land use in the Appalachian coal belt over the last 31 years. They found that since the 1970s, surface mining has impacted 7.1 percent of central Appalachia. The research appears in the journal PLOS ONE.

To create their model, they focused on 74 counties in Kentucky, Tennessee, Virginia and West Virginia. They then analysed more than 10,000 satellite images taken of both visible and invisible light in these counties over the last three decades with a computer algorithm. It assessed each pixel to determine the “greenness” of each 100-square-foot by 100-square-foot section of the images. The algorithm was capable of identifying any area that was not a road or city and appeared devoid of vegetation as a potential mining site, with about 83 percent accuracy.

The results revealed that between 1985 and 2015, roughly 720,000 acres in central Appalachia were directly impacted. Expanding that scope to how much land was impacted between 1976 to 2015, the number jumped to 1.5 million acres. “That’s about 2.8 times the size of Great Smoky Mountains National Park,” lead author Andrew Pericak tells Brittany Patterson at WEKU.

Surface mining is controversial because in mountain-top removal the forests are stripped from ridges before the soil is removed and the bedrock is blasted into rubble. Much of the waste rock is then deposited in the valleys below, blocking or polluting the streams running through them. Wastewater from the mines sometimes also enters local water supplies. Miles O’Brien at PBS Newshour reports that in 2016 the Obama administration’s Office of Surface Mining Reclamation and Enforcement finalized rules that would protect Appalachian waterways from the waste rock and pollution, but one of the first acts of the current administration was an executive order in February 2017 overturning those protections.

The new model also tells a story about the changing economy of coal production. Energy firms began surface mining after the valuable underground coal seams in Appalachia were more or less mined out. After getting the richer coal close to the surface, they have had to go after smaller, less productive coal seams on the mountain ridges, expending more effort and blasting deeper. The numbers from the map bear this out. By comparing data on regional coal production to the amount of land mined, they found that in the 1980s and 1990s it took about 100 square feet of land to produce a ton of coal. “Around 1998, this ratio begins to grow quickly, suggesting coal companies had to mine more land than before to attain the same 1 metric ton of coal," the researchers write in the paper. By 2010, producing a ton of coal took around 160 square feet. As of 2015, it took around 300 square feet.

“It matches up with some predictions that energy analysts have had about just that it takes more effort now to get coal as it becomes a diminishing resource,” Pericak tells Patterson of WEKU. “We think it’s a really strong way to demonstrate that even though we’re really just presenting these maps that can be tied to a lot of different spatial or a lot of different datasets to reach some new and interesting findings.”

Co-author Christian Thomas of SkyTruth says in a press release that the maps can also serve as a baseline to help measure how well reclamation efforts—like replanting forests or turning former mine sites into parks—are progressing. “This is the key to helping the region recover from this legacy of mining and transition to a non-mining future,” he says.