Semester

Spring

Date of Graduation

2000

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Geology and Geography

Committee Chair

Henry W. Rauch

Committee Co-Chair

J. Steven Kite.

Abstract

Land subsidence, caused by longwall mining, has a negative effect on overlying watersheds. Nine streams were monitored from their headwaters to their mouths for discharge, temperature, conductivity, alluvium thickness, and alluvium sediment size. Seven streams are located over undermined longwall panels, with two located over non-undermined areas. Discharge data shows that non-undermined watersheds do not experience stream dewatering, regardless of alluvium thickness or sediment size. Streams located over active or recently mined longwall panels experience water loss that ranges from slight to total. Impacted streams with overall increases in conductivity and decreases in water temperature suggest that lost streamflow travels as underflow, mixing with more conductive, cooler ground water. A thin alluvial cover and poor sorting of streambed sediments appear to prolong stream dewatering. The excavation of stream channels did not remedy dewatering impacts, but returns a positive drainage gradient to the stream channel.

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