Dredging

About: Dredging is a research topic. Over the lifetime, 3300 publications have been published within this topic receiving 28325 citations.

Characterisation and Fate of Suspended Sediments Associated with Dredging Activities in Cleveland Bay

Abstract: Baseline investigations of trace metals in Cleveland Bay sediments highlighted elevated levels close to urbanisation, port activities and the discharge of sewage. A trace metal fractionation study on sediments from the port and dredging channel showed that a major fraction of zinc was associated with the fine sediments generated immediately after dredging and with sediments in the fluid mud layer. A significant fraction of zinc was associated with the organic and iron-bound fraction of the disturbed sediments. Characterisation of sediments collected from coral reefs before, 1 week and 1 month after dredging and dumping activities has shown that 0.5M HC1 leached zinc is a useful tracer of such activities.

Dredging and spoil disposal-major geologic processes in san diego bay, california

Abstract: San Diego Bay is a crescent-shaped, well-mixed estuary 22.5 km long, and initially about 55 km 2 in area, with depths generally less than 4.5 m except for a 7.5-20 m deep channel. The present bay volume is roughly 230 × 10 6 m 3 . Since the early 1900's, dredging and use of spoil disposal as fill have reworked and shifted 100 to 140 × 10 6 m 3 of sediment, with a resulting 27% reduction in the bay's water area and an approximate doubling in depth of 55% of the original water area. Only 17 to 18% of the original area remains undisturbed by dredging or fill. Since the bay reached its approximate present configuration in Holocene time, the only significant sediment source has been river/stream deposition which delivered an estimated 0.8 to 1.1 × 10 6 m 3 annually, until diversion and damming of principal tributaries between 1875 and 1919 reduced sedimentation by more than 80%. For the 30 year period of maximum dredging (1940-1970), the average dredging rate was 3 to 6 times the original sedimentation rate, and roughly 17 to 34 times the sharply reduced present sedimentation rate. Thus, dredging and spoil disposal as geologic processes are substantially more important than all other erosional and depositional processes presently operating in San Diego Bay.

The UK marine sand and gravel dredging industry: an application of Quaternary geology

Abstract: Marine sands and gravels currently contribute 24% (over 20 million tonnes/year) of the total sand and gravel aggregate consumption of Great Britain. To maintain or increase this contribution into the future, the identification, assessment and licensing of additional sand and gravel resource areas is of fundamental importance. Research into the Quaternary history of the continental shelf surrounding the UK assists in the prediction of sand and gravel resource locations. Similarly, resource assessment is significantly improved through an understanding of the origin and formation of these Quaternary deposits. Geological considerations also feature strongly in the management of existing dredging licence areas and in the acquisition of future licences from the Crown Estate. Precise resource assessment, coupled with accurate dredger positioning and track recording systems, minimizes the extent of dredged sea bed, thereby limiting environmental impact and improving the consistency of dredged cargoes. Also important is the need to overcome marine aggregate prejudice which arises from the perception by some customers that marine dredged sands and gravels differ markedly from those obtained onshore. Central to this issue is the argument that some of the most substantial marine deposits originated in subaerial environments at similar times and by the same processes as their present-day terrestrial equivalents, having been deposited in Quaternary cold climate fluvial environments.

Underwater dredging machine

Abstract: The invention relates to an underwater dredging machine which comprises a frame; both sides of the frame are provided with self-walking chasses; the front end of the frame is provided with a lifting frame, and the rear end thereof is provided with a hydraulic workstation and a submersible mud pump; the front end of the lifting frame is provided with a dredging device, and the dredging device comprises a cutter, a scraper and a crusher; a lifting oil cylinder is arranged between the lifting frame and the frame; both ends of the submersible mud pump are respectively connected with a mud suction tube and a mud pipe; and the top of the mud suction tube is connected with the crusher. The hydraulic workstation supplies power to the self-walking chasses, the cutter, the lifting oil cylinder, the submersible mud pump and the crusher. The underwater dredging machine can effectively improve the concentration of dredging mud so that the concentration can reach 20 to 50 percent and is far higher than 10 to 15 percent of general dredgers, and ensure the neatness of the river bed cross section after dredging.