Dredging in a Stratified Estuary

by John M. Smith, Grays Harbor Coll, Aberdeen, WA, USA,
James B. Phipps, Grays Harbor Coll, Aberdeen, WA, USA,

Document Type: Proceeding Paper

Part of: Dredging and Dredged Material Disposal


Grays Harbor is a moderately stratified estuary on the Washington coast. During the summer of 1983, while hopper dredges worked the upper reaches of the estuary, extensive water quality sampling was carried out in conjunction with the dredging activity. As a result of this sampling, it was discovered that dredge-induced mixing of the stratified water column tended to increase the dissolved oxygen concentration above the expected levels in the bottom waters. Furthermore, the entrainment of oxygen rich surface water by the sinking sediment allowed the bottom water to recover to the ambient oxygen levels in five to ten minutes. An incidental result of the study was the discovery that a 200 kHz fathometer could sense and record suspended sediment in the water column.

Subject Headings: Dredging | Estuaries | Water stratification | Hydration | Dissolved oxygen | Water resources | Water sampling | Ports and harbors | Washington | United States

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