Monitoring the tailings dam failure of the Córrego do Feijão mine

On Friday, January 25th, the tailings dam to the Córrego do Feijão mine burst near Brumadinho, State of Minas Gerais, Brazil (the moment of failure was captured on video). Operated by Brazilian mining company Vale S.A., this incident recalls the collapse of Vale’s Samarco Mine in 2015 which unleashed 62 million cubic meters of toxic sludge downstream. As of Monday, the death toll reached 120, however, the full extent of damage is unknown. To monitor the impact, here is a Sentinel-2 scene of Córrego do Feijão from eighteen days before and seven days after the dam’s failure. As of February 2nd, approximately 2.85 km2 of sludge surrounds the region.

Sentinel 2 scene showing the extent of flooding as a result of the tailings dam failure. As a result of the failure, 3 billion gallons of mining waste were spilled.

This slider, below, shows the area near the town of Brumadinho before and after the dam failure with the inundation highlighted in yellow, it can be accessed here.

Satellite analysis shows steep increase in amount of land destroyed to mine a ton of coal in Appalachia

Today at 2:00 pm EST, the Open Access journal PLOS ONE published “Mapping the yearly extent of surface coal mining in Central Appalachia using Landsat and Google Earth Engine”. This paper, the product of a partnership between researchers at SkyTruth, Duke, and Appalachian Voices, provides the first comprehensive map of annual surface coal mining extent in Central Appalachia.

Mountaintop removal coal mining (MTM) is an immensely damaging practice which involves removing rock and soil which overlay coal seams using a combination of explosives and heavy machinery. The removed material is often deposited into valleys, in a practice known as valley fill. Mountaintop removal coal mining is responsible for disturbing thousands of square kilometers of land in Central Appalachia and is the region’s single largest source of land use change.

This animation shows the expansion of surface mining’s footprint (displayed in yellow) from 1985 to 2015 for a 31,000 square kilometer sub-region of the study area in West Virginia and Kentucky, and has county boundaries visible.

In addition to substantial disturbances directly visible on the surface of the land, MTM and subsequent valley fills have been shown to adversely impact stream health as seen by decreases in salamander abundance and aquatic macroinvertebrate diversity. MTM has also been associated with risks to public health in nearby communities, including higher rates of cancer and heart disease.

This study, published today, improves upon earlier SkyTruth work, and creates the first ever dataset of yearly active mining in Central Appalachia. Between 1985 and 2015 our study finds that 2,900 square kilometers (~720,000 acres) of this typically forested region has been cleared as a result of MTM. Coupling our results with our earlier work which dates back to 1976 we find that 5,900 square kilometers (~1.5 million acres) of Central Appalachian forest has been cleared. This is an area 18% larger than the state of Delaware, and roughly 3 times larger than the Great Smoky Mountains National Park.

This image shows a snippet of code used to create the annual mining footprint data, which is visualized in the bottom section of the image. Older mining in this visual is red; newer mining is yellow.

In addition to determining the spatial extent of MTM in Central Appalachia, the study also examined the relationship between the area of land being mined to coal production as reported to the United States Mine Health and Safety Administration (MSHA). Over the course of this study period (1985-2015) we see a threefold increase in the amount of land cleared to extract an identical quantity of coal (from 10 square meters of land per metric ton in in the 1980’s to 30 square meters in 2015).

This dataset is freely available for the public to download, visualize, and analyze the footprint of mining in Central Appalachia. To access all the data, please visit: To explore a subset of the data via an interactive web map, please visit:

Planet Imagery sheds light on Mine Expansions outside of Permit Boundaries

We were recently reviewing imagery of mine sites which experienced growth in 2017. We overlaid the mine permit boundaries that show where the government has legally granted companies permission to mine. We used our Landsat-based surface mining data to identify a set of candidate sites to examine more closely with higher-resolution Planet imagery through Planet’s Ambassadors Program. While looking at these sites, we noticed mining activity that seems to be occurring outside of permitted areas.

The Taywood West Mine as it appeared on a high-resolution Planetscope satellite image in July 2017. The mining permit boundary is shown in red; mining-disturbed land, based on SkyTruth’s analysis of lower-resolution Landsat 8 satellite imagery, is shown in orange and closely matches what we are able to see in this Planet image.  Apparent mining-related activity outside the permit area is highlighted in yellow.

The mine site continued to expand after July; the image below shows the extent of mining on October 19. More land outside the permit boundary appears to have been cleared since July 30.

The Taywood West Surface Mine is located in Mingo County, WV approximately 12 kilometers northeast of the town of Kermit and 76 kilometers southwest of the state capitol in Charleston.

The Taywood West Surface Mine (pictured above) caught our attention when we noticed evidence of mining activity, which fell outside the mine’s permit boundary. In the image, areas overlain in red show the extent of the mining permit; the bright areas of bare rock and soil on the image show where mining activity (cut and fill) activity has apparently occurred as of the date of the image (October 2017). Fifty-two acres of mining-disturbed land lie outside of the permitted area. According to permit data downloaded from the West Virginia Department of Environmental Protection (WVDEP), the permit for the Taywood West mine was issued to Southeastern Land, LLC in August 2005 and will expire in August 2020.

A 2004 study conducted in West Virginia showed a surprisingly high degree of mismatch between permit boundaries and actual mining, but we thought the situation had improved since then. Now we are not so sure, and we’re wondering how widespread this problem is. Accurate assessment of the location and amount of existing mine-damaged land is critical for forecasting the cumulative downstream impacts of mining in deciding whether to approve permit applications for new mining. And it’s critical for planning and executing the extensive reclamation work this region needs to recover from the negative impacts of coal mining. Whose job is it to make sure miners stay within the boundaries of their mining permit?

Update on Our Efforts to Map Surface Mining in Appalachia

Some time has passed since we’ve written about our work mapping surface mining in central Appalachia, but rest assured, we’re still actively monitoring this devastating practice. Our mining work to date has focused on mapping the locations of these operations.

Researchers, some of whom are using our data, are beginning to draw troubling connections between coal mining and the health of people living in communities near those operations. We are working to refine our mapping processes and enable new types of analysis to help understand the environmental and public health consequences of mountaintop removal mining.

The process we used to create our annual maps of surface mining from 1985-2015, relies on the use of a Normalized Difference Vegetation Index (NDVI). NDVI essentially measures a ratio of reflected red and near-infrared light and is particularly useful for detecting changes in vegetation. When areas within the scope of our study experience a change from forest to bare earth, this registers as mineland. The analysis is available here:

This NDVI image shows the Hobet 21 Coal Mine in West Virginia. Vegetated areas are visualized in white, while bare earth is seen as dark grey or black.

We are working with Dr. Matt Ross, an ecosystem scientist from the University of North Carolina at Chapel Hill, to improve our mining identification algorithm, and add the capacity to evaluate how landscapes affected by surface mining recover over time. This algorithm is an integral step in assessing the efficacy of the reclamation efforts undertaken by mine operators. We expect our mapping will allow researchers to conduct more robust studies on the long-term environmental and health impacts of surface mining, which in turn will help mining-impacted communities hold industry and government accountable for repairing the damage done to Appalachian landscapes, ecosystems and public health. We also hope the work will stimulate government investment as coal mining declines throughout the region, enabling a just transition to a new economy.

The following slider compares one of the new indexes we are incorporating into our work, a Normalized Difference Moisture Index (NDWI), with NDVI at the Hobet 21 Coal Mine. NDWI measures the relative amounts of moisture present in landscapes, densely vegetated areas have high NDMI values, while sparsely vegetated areas or bare earth have lower values. By incorporating new indices we are gaining a better understanding of how the land is affected by these operations. It is worth noting, therefore, the low amount of moisture present across the mine, even in those areas which appear to be recovering in the NDVI.