PRE-SMCRA MINE WASTES AND FLOODPLAIN ENCROACHEMENT: DEADLY FLOOD HAZARDS IN SOUTHERN WEST VIRGINIA, USA

Several late spring and summer floods during 2001 and 2002 demonstrate how landscape disturbances in southern West Virginia exacerbate flooding. Three floods in 2001 left 6 dead and >$143 million damage, with most damage occurring on 8 July. A May 2002 flood on killed 7 and caused >$24 million damage. Rainfall in each event was 50-150 mm in 4-6 hr, but property damage and geomorphic response was comparable to floods produced by much more intense storms elsewhere in the Appalachians. Scientists and laymen agree that something is "wrong" on the rugged Southern West Virginia landscape and it is increasing flood impact. Popular opinion is that mountain-top removal and valley-fill coal mining is largely to blame, augmented with local contributions from timbering and gas-well disturbance. While these factors contribute to the flooding, two important controls have drawn little attention: floodplain encroachment and old mine wastes. Many flooded communities lie on 50 to 100 m wide bottomlands covered by a railroad, a highway, several rows of houses, and a narrow, channelized creek. Floodplain landforms are so "filled in" that it is impossible for the streams to top their banks without causing damage. Mine wastes may represent the most lethal flood hazard in the region. The Surface Mine Control and Reclamation Act (SMCRA) of 1977 requires reclamation of all new mines and has led to reclamation of a few abandoned mines, but many of these reclaimed areas spawned debris flows or hyper-concentrated flows in 2001-2002, especially in approximate original contour reclamation. The greatest risk is presented by unreclaimed pre-SMCRA mine wastes cast over the landscape at angle of repose. The 8 July 2001 flood alone generated hundreds of failures in pre-SMCRA mine spoil, and ample evidence indicates similar failures occurred frequently in the 20th Century. Streams downstream from mine-waste failures were very erosive and exceptionally damaging in recent floods. A truly intense (300-400 mm in 6 hr) future rainfall event would have the potential to kill hundreds and leave >$1 billion damage.