Characterizing streamflow response of a mountaintop-mined watershed to changing land use

Mountaintop removal mining is a dominant driver of land use/land cover changes in the Appalachian Region of the eastern United States and is expected to increase in scale in the coming decades. While several studies quantify land use/land cover changes attributed to traditional surface mining and at regional scales, no studies we are aware of focus specifically on mountaintop removal/valley fill mining practices at the watershed scale. Further, despite its scale and extent, its impact on runoff, particularly at larger spatial scales (10³ km²), is poorly understood due to the complex relationships between climate, land use, and hydrology. To explore the impacts of this practice at broader scales, we estimated land use/land cover changes using Landsat 5 TM imagery over five periods between 1994 and 2010; used a simple rainfall–runoff model to estimate hydrologic response time; and conducted non-parametric trend analyses on annual hydrologic metrics (streamflow, Q/P, response time) for the Big Coal River watershed located in the southern West Virginia coalfields. No statistically significant trends were detected in any of the timeseries. The lack of detectable trends and correlations between land use changes and hydrology at the basin scale are not entirely unexpected due to the history and mosaic of land cover changes that span timescales larger than our study period. Further interannual variation likely overwhelms our ability to detect potential changes using monotonic trend analysis at the annual time scale, particularly in light of strong streamflow seasonality. Future studies therefore should include different methods of change detection applied to different timescales to more appropriately account seasonal and interannual variations. Until the significance of this practice on water resources (quality and quality) are understood, efforts to reduce the environmental problems associated with mountaintop mining will be difficult to achieve.