Document Type

Report

Department/Program

Virginia Institute of Marine Science

Publication Date

11-1-1990

Series

Special Reports in Applied Marine Science and Ocean Engineering (SRAMSOE) No. 307

Abstract

Chesapeake Bay is a depositional basin that is filling from both ends and the sides. During the century ended in the mid-1950s between 1.0 x 109 and 2.92 x 109 metric tons of sediment accumulated in the bay. The bay's largest tributary, the Susquehanna River, is a major source of fine-grained sediments; its coarser load being trapped by dams. The continental shelf is the largest single source of sediment for the basin. A massive quantity of sand, perhaps as much of forty percent of the net deposition, enters the bay between the Virginia capes and works its way tens of kilometers upstream, potentially as far north as Tangier Island, near the Virginia-Maryland boundary. Other sources of sediment are shoreline erosion, biogenic production, preHolocene outcrops, and the other tributaries. These tributary estuaries do provide coarse sediment to the bay through longshore transport and bedload movement in the nearshore.shallows and, perhaps, in the channel bottom. The contribution of suspended or fine-grained sediment by the tributary estuaries is unknown. Indeed they may be sinks and not sources. 'The contribution of the tributary estuaries and the quantification of the bay-mouth sand-source and uncertainties associated with the bathymetric comparisons in the determination of the net mass of sediment deposition, make it difficult to balance a sediment budget for Chesapeake Bay. Most of the imbalance is in the sand fraction within the Virginia portion of the system; with far more sand being deposited than can be accounted for by the independently quantifiable sources. Not considering the continental shelf as a source of sand, the budget fails to balance by a factor of between 2.7 and 7.6. Making certain assumptions about the quantity of sanQ entering the bay through its mouth (the continental shelf source), the difference can be sufficiently reduced that the budget more nearly balances.

DOI

https://doi.org/10.21220/V5RX6S

Keywords

Sedimentation, Chesapeake Bay, Depositional Basin

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