MEGA CURRENT BEDFORMS OF THE SUSQUEHANNA RIVER: FEATURES THAT FORM FROM MAJOR FLOOD EVENTS
They can not be observed easily at ground level. Ideal conditions are necessary to observe them using remote sensing. These large structures have eluded previous detection because ideal conditions are necessary for their formation, their size, and because they may easily erode between flood events. They have been observed on some historical aerial photographs in the Susquehanna River substrate. Strong downpours, ice jams, disturbance by lithophilic fish, and subsequent high energy flood events may modify the bedform structures.
The mega current bedform structures are significant because they represent the movement of massive amounts of coarse sediments from tributaries into and along the river substrate. The downstream movement of this sediment influences benthic macroinvertebrates (BMI) both during and following major flood events. Mega current bedforms may also contribute to alluvial bar island formation. Large bedforms such as these represent a disequilibrium in the river system as mostly unconsolidated Pleistocene glacial outwash and recent sediment is transported downstream during high-energy events.