Mountaintop mining with valley fill (MTM/VF) in the Appalachian region of the eastern US represents a significant alteration of the landscape with a multitude of accompanying processes impacting water quality as well as the risk of floods. In spite of its widespread use and its acknowledged impact on water quality and quantity, the changes in the basic stream processes are poorly defined. This project will collect hydrologic and meteorological data, sample and analyze stream and precipitation for O-18 and deuterium beginning August 2010, prior to the start of mining operations. The project will also measure streamflow and chemistry at the outlet of Sycamore Creek and continually track stream stage.
Mountaintop removal mining (MTM) practices are a dominant driver of land-use/land cover changes in the Appalachian Region of the eastern U.S., with a potentially profound influence on runoff and flood generation processes. Several devastating floods in this region have been attributed to be the consequences of these activities, but there is little quantifiable evidence on the actual extent to which such practices impact hydrologic processes. The research objective of this study is to elucidate primary controls on catchment stores, flow paths, and transit times of water in MTM-impacted catchments to better understand dominant factors in streamflow generation through the use of stable isotope techniques. The original experimental design for this study was based on a pre- versus post-mining comparison of streamflow generation processes. However, the Environmental Protection Agency indefinitely suspended permits for mountaintop mining until the environmental impacts associated with this practice are better understood. As a result, the mining disturbances in Sycamore Creek have not yet occurred. Because of the delay in mining, a MTM-impacted catchment (White Oak Creek) adjacent to Sycamore Creek was instrumented to provide a comparison of streamflow generation processes between a largely forested catchment and a MTM catchment. The reframed objective of this study therefore is to compare streamflow generation processes in MTM-impacted catchment to an undisturbed forested catchment. Though this design is not ideal, it does provide basic information to move forward on understanding mining impacts and developing a rigorous approach for future proposals. Preliminary analyses of fall season storms indicates that as much as 51% of streamflow can be attributed to precipitation (event water) in the undisturbed, forested catchment (Sycamore) whereas event water accounted for 79% of streamflow in the MTM impacted catchment (White Oak). Mean transit time in Sycamore Creek was 10 hours compared to 5 hours in White Oak Creek. The greater proportion of event water during storms and a shorter storm transit time in White Oak was attributed to mountain-top removal mining and valley fills that occupy nearly 34% of the catchment area. Rapid time-to-peak and large contribution of event water are attributed to infiltration-excess overland due to impervious surfaces, compaction, reduced porosity, the removal of soils and vegetation as wells as possible preferential flow through mine spoil. Alternatively streamflow in the forested Sycamore Creek was dominated by pre-event water indicating that streamflow generation is dominated by primarily subsurface flow paths, common in forested catchments. These preliminary results indicate that MTM not only affects the timing, peak flow, and total streamflow as documented through earlier studies, but also changes flow paths, thereby increasing flood potential. It is important to recognize that these findings are only preliminary and the hydrologic responses in these catchments are highly variable. Therefore a thorough comparison is being conducted for a Master of Science thesis that is expected to be defended in May 2013. This project also contributes beyond physical hydrology. Stream chemistry in this region is strongly influenced by contact time with geology and mine materials such as valley fills and mine spoils. Increased Total Dissolved Solids (TDS) and selenium have important implications to aquatic ecosystem health (salinity, bioaccumulation, etc) and is the foundation of the US EPA's regulation of this land use practice. Currently we are exploring the relationship between event water transit times through surface mines and valley fills, geochemical evolution of streams that drain mountaintop mines, and benthic organism responses to mining. Thus, we are contributing to ecology by linking streamflow generation processes, water quality, and ecosystem response. The research funded by this award is expected to aid policy makers in the development of science-based environmental regulation about the environmental implications of this method of resource extraction. Further, millions of dollars are spent on reclamation and stream restoration, yet the basic hydrology of the systems is not well understood. The progression of research initiated in this project is expected to ultimately yield a fundamental understanding of how large-scale landscapes disturbances such as mountaintop mining impact catchment scale hydrology and stream water quality thus providing a conceptual framework for the development of more effective environmental management, restoration, and reclamation. With the expected increase of this practice in the Appalachian region, and the world's continued and increasing reliance on coal, the knowledge gap of the environmental impacts of this relatively understudied disturbance needs to be filled. Until the significance of this practice on water resources are understood, efforts to reduce the environmental problems associated with mountaintop mining will be difficult to achieve.
