Shell dredging. A factor in sedimentation in Galveston Bay.




Masch, F.D.
Espey, W.H., Jr.

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University of Texas at Austin, Center for Research in Water Resources, Hydraulic Engineering Laboratory


Detailed field studies were undertaken to determine the movement of sediments resuspended by dredging operations in a localized area of Galveston Bay, Texas. The extent and manner in which sediment movement occurred and the conditions under which dredge sediments could be expected to move on to natural reefs and possibly deposit are discussed. The effects of tidal currents, type of overburden sediments, topography and number of dredges in operation have also been investigated. Although this study provides information on currents and sedimentation that is applicable to other parts of the Galveston-Trinity Bay system, investigations were restricted to the area of most intense shell dredging activity. This included an area of about twenty square miles between Redfish Island and Eagle Point. The study was carried out from an engineering standpoint, and investigations were restricted to the effects that the physical characteristics existing within the Galveston Bay system, and in particular the study area, had on the dynamic behavior of the sediments. Controlled laboratory tests on sediment movement were also carried out. These tests provided data on the conditions under which a sediment density layer would form, the effects of water currents and bottom slopes, and the behavior of sediment density layers at abrupt changes in bottom topography such as reefs, dikes, trenches, and dredge cuts. Based on field and laboratory observations, large scale measures were devised to control sediment movement from dredging operations. Data are included on the effectiveness of a submerged dike, and a trench as control measures. The effect of opening a pass and increasing the flushing action on sediment movement in a localized area is also noted.


168 p.


shells, oyster reefs, dredging, sediment movement, sedimentation