Channel dredging

Obstacles and hard ground can affect excavations to required depths, such as in navigational channel dredging projects, or steel piles requiring to be driven to a certain level. Obstacles frequently encountered include old, temporary or abandoned permanent works and sunken vessels. In such cases, obtaining detailed local knowledge or a diseussion with the relevant authorities such as the Harbour Master can often reveal much information. 

Dredging channelizing Shoreline protection Fish/hunting Timber harvest Boating ... 

Loosening and lifting earth and sand from the bottom of water bodies. Dredging is often carried out to widen the stream of a river, deepen a harbor or navigational channel, or collect earth and sand for landfill it is also carried out to remove contaminated bottom deposit or sludge to improve water quality (PIANC, 2000). Volume 2(9). 

Trace element abundances of rocks dredged from the Sicily Channel seamounts are scarce (Beccaluva et al. 1981 Calanchi et al. 1989). They show variable concentrations, with incompatible element abundances increasing from tholeiitic to alkaline basalts and basanites (Fig. 8.17). Mantle normalised incompatible elements define bell-shaped patterns (not shown), which resemble those for the exposed rocks in the Sicily Channel. 

Winding sluggish canals Dredged earth channels Natural-stream channels 0.025 0.021... 

Much of the bottom of the Sound within the wave-affected zone is sandy. In some localities where the shore is bedrock, deposits of muddy sediment form up to the surf zone. This is possible because mud is trapped in mats of algae that mantle the bottom near the shore. Muddy material also accumulates in the dredged shipping channels of the harbors along the Connecticut shore at an average rate of 4 mm/yr, as computed from records of maintenance dredging (Bokuniewicz and Gordon, 1979). The surface area and volume of all of these deposits is small compared to the area and volume of the muddy sediment below the wave-affected zone. The rest of this article deals mostly with these deep mud deposits. 

Ramser, C.E. (1919). Progressive erosion in a dredged drainage channel. Engineering News-Record %2 %y. 876-877. 

Nonavailability of rock material in sufficient quantities and at affordable costs. Avoiding sediment infiltration through rubble mound structures which may result in the shoaling of navigation channels and harbor basins, and thus in higher maintenance dredging costs. 

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