What is Dredging? Types,Maintenance,Use and Operation

✔Dredging

Dredging is defined as excavation of bed below water.

This technique is often used to keep waterways navigable.It is also used as a way to replenish sand on some beaches, where too much sand has been lost because of coastal erosion.Dredge or dredger, is the equipment that carries out dredging work.To know where dredging is necessary, hydrographic survey is performed in the entire basin.

✔PRIMARY DREDGING

If the dredged materials are to be removed only once, it is known as primary dredging.Dredged materials are removed only at the start or opening of harbour.

✔CAPITAL DREDGING

Initial removal of material to obtain required depth.This depth acquired is maintained regularly to have a convenient harbour.Materials removed includes hard rocks and even silt.

✔MAINTENANCE DREDGING

It is a dredging to deepen or maintain navigable waterways , which are threatened to become silted with the passage of time.

Materials removed will be in the form of fresh deposits (sand andsilt) only.It is carried out periodically to maintain the navigable depth.

✔Use of dredging

1.For ensuring proper depth at the harbour or ship channel

2.For the maintenance of the harbour

3.Land reclamation- dredged materials used to construct new land.

4.Beach nourishment.

5.Seabed mining- recovering natural metal ores.

6.Construction materials- dredged sand and gravel can be used in construction industry.
7.Contaminant remediation- to reclaim areas affected by chemical spills,

Earth moving machine to remove bed material from under water, to increase the water depth.i.e. for dredgingDredgers can be classified into two:
✔Mechanical dredge
✔Hydraulic dredgers

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