What are the types of dredging? What is the difference in mechanical and hydraulic dredging?

Mechanical and hydraulic dredging are the two main types of dredging methods.  Mechanical dredging is the removal of sediment with the use of a bucket, usually with an excavator.  Draglines and clamshells are the other types of mechanical dredging methods.  Hydraulic dredging involves a barge with a pump that vacuums sediment from beneath the water’s surface and pumps it through a pipeline to a different location.  Both are effective in certain applications.