THE PAST, PRESENT, AND FUTURE LOCATIONS OF THE STREAM OF MEADOW RUN, BLUE RIDGE MOUNTAINS, VIRGINIA

The stream of Meadow Run flows on the western flank of the Blue Ridge physiographic province near Grottoes, Virginia. The channel cuts through Pleistoncene-Quarernary alluvial fans that are composed of saprolitized cobbles of Antietam Quartzite, the Shady dolomite, and deeply weathered fluvial deposits. The stream itself is an intermittent, multi-threaded channel that flows to the northwest, joining with the South River. The course of the channel is undergoing avulsions that are activating many rotational slides on the perimeter of alluvial fans that border the bank of the stream. These avulsions are activated when major flooding events occur. Each major hurricane that has occurred during the past several decades (e.g., hurricanes Camille (1969), Agnes (1972), Juan (1985), Fran (1996), and Isabel (2003)) has supplied enough energy through the system to activate the avulsions. Sequential air photos from the 1930s to present, Light Detection and Ranging (LIDAR) imaging, and field reconnaissance are being used to map the past and present channel locations. Predictions of the future locations of the stream are being developed from the headward migration of active knick points. These knick points are found in the avulsion on the southeast flank of the stream, giving evidence that the stream is changing its flow pattern as it tries to reach a point of equilibrium. Knick points are formed as more resistant rock or in this case trees that hold the sediment, erode away vertically and headward so that the stream can reach a graded long profile where the available energy of the river and the processes of the river are balanced. Bed load in the avulsions is also grading upward from flood plain silts and sands to channel pebbles and cobbles, providing further evidence for adjustments in the channel path. By acquiring insight into changes in channel evolutions we can begin to develop an understanding of how rivers respond to high energy conditions.