Dredging is the act of digging out and removing material from underwater by means of a machine equipped with a continuous revolving chain of buckets, a scoop, or a suction device. Dredging and the disposal of dredged materials have the potential to cause physical and biological damage, particularly when removed sediments are contaminated with toxic substances. This study has been conducted to assess the environmental effects of dredging and dredged material disposal and to discuss improved dredging techniques friendlier to the environment using dredging data during the construction and the maintenance works at Elsukhna Port Egypt from 1999 till 2006. Both mechanical and hydraulic dredging techniques are used, which introduce significant quantities of sediment into the water column immediately adjacent to the operating dredge. Dredging also affects channel depth which alters local circulation and sediment transport. Changes in mixing and gravity circulation can affect the distribution of dissolved oxygen and other water-quality parameters, and the relationships between changes in channel geometry and changes in circulation and channel shoaling have been detailed in a variety of studies. In the case of dredging and dredged material disposal, it appears that far more is known about environmental effects and probable causes than is incorporated in regulatory criteria and environmental practices. |
