Quantitative evaluation of mining-induced changes to spring discharge above a mine in the northern Appalachian coal field.

摘要

The objectives of this research were to develop methods to discern between naturally occurring reductions in spring discharge from mining-induced reductions to spring discharge, evaluate available hydrologic, geologic, topographic, and mine-specific variables to determine which variables are related to mining-induced spring discharge impairment, and evaluate the variables to determine the seasonality differences or similarities among the variable effects. The study area is at one mine site in the northern Appalachian coal basin.;Overburden thickness of the researched ground water sources above the mined coal bed level range from 135 feet to 550 feet. The overburden geology consists of cyclothemic deposits of sandstones, siltstones, shales, limestones, clays, and coal that comprise the Conemaugh and Monongahela Groups of Pennsylvanian age, and the lower part of the Dunkard Group, Washington and Greene Formations, undifferentiated, of Pennsylvanian and Permian age. The terrain of the research area is typical of the Appalachian Plateau physiographic province, having broad ridges, deeply incised valleys, and highly defined dendritic drainage. Land use is dominantly for farming. Average annual precipitation in the research area is 43 inches.;Mining-induced subsidence resulted in a partial environmental effect to springs. Spring discharge responses for 77 springs were evaluated across subsidence events. The methodological procedure developed through numerous, iterative investigations differentiated quantitative values separating natural changes in spring discharge from mining-induced changes to spring discharge. The influences of precipitation and evapotranspiration conditions were accounted for during the natural variation analysis used to determine if changes to spring discharge were mining-induced.;In addition, topographic, geologic, hydrologic, and mine-specific variables were statistically examined for significance of influence on spring discharge impairment during low and high evapotranspiration seasons.