FROM THE BIRTHPLACE OF RIVERS TO THE GREENBRIER CLASSIC: EXCEPTIONAL FLASH FLOODING IN WEST VIRGINIA ON 23 JUNE 2016

Repeated lines of intense convective storms along a stationary front on 23 June 2016 produced rainfall of 100-200 mm over a >4000 km² area in West Virginia and adjacent Virginia. Resulting flash floods led to at least 22 fatalities, costly property damage, cancellation of a prestigious PGA golf tournament, and record or near-record flood stages in portions of the Greenbrier, Elk, and Gauley river basins. Runoff was exceptionally flashy because of antecedent moisture, high topographic relief, steep slopes, narrow floodplains, and high-gradient streams. USGS gages reached peak flood crests in 12 to 24 hours and recorded stage rises of up to 9 m on Elk River, and 6 to 7 m on Meadow and Gauley rivers. Lower Greenbrier River hydrographs lagged somewhat behind others in the region, possibly because of runoff storage in karst systems. Howard Creek and several other streams with <100 km² drainage areas experienced truly exceptional runoff, erosion, and sediment transport. Landslides were common in areas of highest precipitation, as was sinkhole flooding and cave passage modification in limestone areas. Mitigation efforts removed much of the sedimentological and geomorphological evidence of the event in the weeks immediately following 23 June, but ubiquitous social media postings provide evidence key to reconstructing conditions during and immediately after the floods. Deadly flash floods have been recurring geologic hazards in the West Virginia and the rest of the central Appalachians throughout recorded history, but cataclysmic floods are likely to increase in frequency due to a recent trend of increasing high intensity rainfall.