FLOODS AND PALEOFLOODS IN THE GREENBRIER RIVER BASIN, WEST VIRGINIA
Four USGS gaging stations exist on the Greenbrier River; two upstream and two downstream of GRC and CAC. Evidence of the three largest floods at the two downstream gages (1985, 1996 & 2016) are preserved within GRC and represent three different flood generating mechanisms. Using paleostage indicators in GRC and the gage discharges it has been possible to back-calculate Manning roughness coefficients (n) for the channel outside GRC during multiple floods using hydraulic modeling (HEC-RAS). Minimum n-values are calculated to be 0.027 to 0.035.
To date, numerous Holocene paleofloods have been successfully documented in the two caves. Three prehistoric large floods have been recognized in GRC and a sequence of lower magnitude paleofloods are present in CAC slackwater sediments. The discharges of the prehistoric floods recorded in GRC are similar to those in the historical record. However, the largest prehistoric flood had a minimum stage that was close to the peak (maximum) stage of the largest historic flood, so may have been substantially larger.