Sand Suction Machine

How does a sand dredging machine work.Everflowing pumps sand dredging machie work in river sea.How to choose sand dredging machine.Everflowing sand dredging machine include simple dredger,jet suction dredger,cutter suction dredger,submersible dredger,bucket chain dredger,and so on.We can choose suitable dredging machien according to work.