Abstract
Few land disturbances impact watersheds at the scale and extent of mountaintop removal mining (MTM). This practice removes forests, soils and bedrock to gain access to underground coal that results in likely permanent and wholesale changes that impact catchment hydrology, geochemistry and ecosystem health. MTM is the dominant driver of land cover changes in the central Appalachian Mountains region of the United States, converting forests to mine lands and burying headwater streams. Despite its dominance on the landscape, determining the hydrological impacts of MTM is complicated by underground coal mines that significantly alter groundwater hydrology. To provide insight into how coal mining impacts headwater catchments, we compared the hydrologic responses of an MTM and forested catchment using event rainfall-runoff analysis, modeling and isotopic approaches. Despite similar rainfall characteristics, hydrology in the two catchments differed in significant ways, but both catchments demonstrated threshold-mediated hydrologic behavior that was attributed to transient storage and the release of runoff from underground mines. Results suggest that underground mines are important controls for runoff generation in both obviously disturbed and seemingly undisturbed catchments and interact in uncertain ways with disturbance from MTM. This paper summarizes our results and demonstrates the complexity of catchment hydrology in the MTM region.
Highlights
Determining the hydrological impacts of an individual disturbance from multiple, overlapping disturbances in space and time is a major unresolved issue for hydrological sciences [1], even when considering landscape-scale disturbances, such as mountaintop removal mining (MTM)
This paper summarizes our results and demonstrates the complexity of catchment hydrology in the Keywords: mountaintop removal mining; catchment hydrology; disturbance hydrology; streamflow generation; underground coal mining
Surface mining for coal is the dominant driver of land cover changes [8,9] in the portion of the Appalachian Coalfields region within West Virginia, Kentucky, Virginia and Tennessee, impacting nearly 7% of the mostly forested 4.86 million hectare area (Figure 1), burying ∼4000 km of headwater streams under valley fills [10]
Summary
Determining the hydrological impacts of an individual disturbance from multiple, overlapping disturbances in space and time is a major unresolved issue for hydrological sciences [1], even when considering landscape-scale disturbances, such as mountaintop removal mining (MTM). MTM is a special form of surface mining adapted to mountain landscapes that removes forests, soils and overlying bedrock to gain access to underground coal seams. This practice leads to likely permanent and wholesale changes to catchment organization, structure, soils and vegetation that have important implications for catchment hydrology, geochemistry and ecosystem health [2,3,4]. The challenges of conducting research in heavily-disturbed and ever-changing environments [11] often prevents process-based and long-term studies, and the challenges of isolating the hydrological impacts of one disturbance within the context of multiple, overlapping disturbances [1] precludes better understanding of the hydrological changes that result from MTM
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