Reconstructing Legacy Floodplain Storage from Strip-Mining in Western Pennsylvania

Abstract:

Strip mining moves large amounts of rock and soil, accelerating erosion and downstream deposition. The impacts of coal strip mining on downstream riparian areas have not been evaluated, particularly the amount of mine spoil that was eroded and deposited in floodplains. The increase in legacy floodplain sediment storage impacts ecology, water quality, and flood risk. Accelerated soil erosion and downstream sedimentation has typically been associated with agriculture and underground mining, but the floodplain impacts of strip mining have not been reconstructed. Soil cores and borings were collected downstream from extensive mining in intact floodplains (Settler’s Cabin Park, Pittsburgh, Pennsylvania) to quantify floodplain storage. The borings were classified for field color and texture and cores were radiometrically dated to reconstruct sediment accumulation during strip mining in these watersheds. Legacy soil sedimentation rates associated with widespread strip mining are similar to or larger than those observed during initial agricultural land clearance.