Seasonal water table dynamics of a southern Appalachian floodplain and associated fen

Appalachian mountain alluvial wetlands include floodplain forests intersper sed with fens or bogs. This study evaluates the water table dynamics of an Appalachian mountain floodplain which includes a depressional fen. Water ta ble wells and piezometers documented seasonal patterns of the water table a nd the vertical hydraulic gradient (VHG) in the floodplain and fen areas. A dditional water table wells determined the potential sources of water from adjacent hillslopes to the fen area. The water table of the floodplain and the fen exhibited distinct regular seasonal fluctuations. The water table r emained near the surface of the fen from late winter through late spring an d dropped 20 to 80 cm during the summer between precipitation events. The w ater table of the floodplain fluctuated more but followed similar patterns and was typically within 40 cm of the surface during late winter and early spring months and greater than 60 cm during the summer months. The water ta ble of the floodplain was more often correlated to precipitation than the w ater table of the fen. The VHG in the floodplain was highly variable althou gh seasonal patterns of upwelling of water in fall and downwelling in winte r were common. The VHG of the fen showed a consistent downwelling of water and suggested that the fen serves as a recharge area for an aquifer. Princi pal sources of water for the fen appeared to be precipitation, inflow from a shallow aquifer on an adjacent slope plus increased interflow associated with precipitation events from another adjacent slope. The influence of soi l texture on water dynamics of the fen or floodplain was not fully ascertai ned but ii; appeared to influence horizontal flow from hillslopes and the d epth of the water table in the fen.