Dredging Basics

Dredging involves excavating an area that is at leastcases of missing people, even bodies.
partly submerged. This can involve anything from aDredging is very important in containment of chemical
river or lake to the open seas. There can be severalspills, too. In these cases, as much of the contaminated
reasons for dredging an area, but the most commonsoil is dredged up as possible and then disposed of in
reason is to gather the sediment from the bottom ofsome other, safer location. Doing so right away can
the lake or section of ocean and then redeposit orhelp protect the local sea life and restore the area to
dispose of this sediment elsewhere. In many cases, thenormal quickly. It also prevents chemicals from getting
reasoning behind doing a dredge of an area is to keepinto seafood and local water supplies.
the sediment from building up. In some waterways, forSome environmentalists have suggested the dredging
example, if too much sediment builds up, larger shipsdoes impact aquatic ecosystems, and they are
may not be able to use the waterway. In this samecorrect to some extent. Dredging can dislodge
way, dredging can also be used to increase achemicals, including heavy metals, in the benthic
channel's or river's water capacity to help relievesubstrates of the ocean floor, causing these chemicals
flooding in some areas.to enter the water. The turbulence dredging causes,
There are some other uses for dredging. Coastalalthough very short term, can also cause some
erosion, caused by the waves over times, can leavedisturbances in local species migration and metabolism.
some public beaches without a good amount of sand.There's also a small chance that the sediment taken
This makes them less attractive to tourists, which infrom the area will contain something that contaminates
turn means a drop in income for the surrounding area.the site where it is deposited, although samples of the
Dredging up sediment and sand from the bottom cansediment are usually taken and tested before the
be deposited on the beach to help rebuild the lost sand.sediment is deposited.
Sand gained from dredging can also be used in landHowever, despite the impact dredging can have on the
reclamation projects and other construction projects.environment, without dredging, much of today's modern
Another use of Dredging is in fishing. Some ediblecommerce would not be as efficient or as effective.
crabs, clams, and other seafood can be dredged upWithout dredging to clear harbours, channels, and
from the ocean bottom. After the sand is filtered out,rivers, cargo ships could not access many ports.
these edible fish can be sent to restaurants and foodRecreational boating, too, would be impaired, with all but
packaging plants for preparation and consumption.the smallest ships able to sail on some lakes, rivers,
Dredging may be used to search through the sedimentand seas.
for other things, including gold, rare minerals, and, in