Spatial and Temporal Variability in Suspended Sediment Characteristics in the Surface Layer of the Upper Chesapeake Bay

Abstract

Periodic high discharge events flush suspended sediments from the Susquehanna River and Conowingo Dam reservoir into the upper Chesapeake Bay, which extends from the mouth of the Susquehanna River to the Bay Bridge near Annapolis, MD. Sediment characteristics in the surface layer of the upper Bay and changes in these characteristics with varying river discharge and distance downstream are not well known. In order to develop an integrated understanding of surface layer sediment dynamics, several in-situ data sets were examined at the Bay head and downstream along the Bay’s center channel, providing data on the spatial and temporal variability of suspended particle characteristics including concentration, settling speed, bulk density, and size. It was found that particles are entirely disaggregated at the Dam, later aggregating to a limited extent down Bay, and that downstream characteristics are more weakly linked to Susquehanna flow at lower flows and longer distances.