Chesapeake Bay Sediment Budget

Abstract

Chesapeake Bay is a depositional basin that is filling from both ends and the sides. During the one hundred years ending in the mid - 1950's between 1.0 x 10⁹ and 2.92 x 10⁹ metric tons of sediment accumulated in the bay. The water of the continental shelf, flowing into the hay's mouth, is the largest single source of sediment for the basin. A massive quantity of sand, perhaps as much as 40% of the net deposition, enters the bay with these waters and moves tens of kilometers up-estuary. The Susquehanna River is a major source of fine-grained sediments; its coarser load is trapped by dams. Other sources of sediment are shoreline erosion, biogenic production, and, perhaps, the tributary estuaries. The tributaries do provide coarse sediment through longshore drift and bedload movement in the nearshore shallows and, perhaps, in the channel bottom. The quantity of suspended sediment supplied by the tributary estuaries is unknown. Indeed the tributaries may be sinks not sources.