- On 17th January 2020
- In Dredging, General
- By David
This might sound like a basic question, but the answer can be very varied as dredging can have many different effects depending on the specific case. To start off, dredging is the process of moving material within or out of a water environment. There are many different methods of dredging, with the most basic using mechanical grab excavators, to very complex cutter suction dredgers which effectively vacuum sediment off the waterbed and pump it to the place where it is used.
Discussing the types of dredging is a topic for another blog post, so let’s consider the impacts first. In its most basic form, dredging is used to deepen or widen a navigational channel with the purpose of improving access for boats. This can be to enable navigation at lower tides, or to enable larger boats and ships to safely use the channel. This is perhaps the most important reason why dredging projects happen. In the UK, most ports and harbours are not natural harbours but will naturally silt up to shallower depths. It is a never-ending battle.
With increased emphasis on the re-use of the dredged material and working with nature, it requires specialist knowledge to get dredging projects approved by the regulating bodies such as MMO. At Exo we specialise in innovative solutions to dredging projects which are otherwise considered too complex or impossible due to the sensitivity of the surrounding environment. Check out our case studies such as the USAR habitat restoration, or follow our progress within the SARCC project, where we focus on nature-based solutions.
Another important reason/advantage is it enables the construction of structures that are near a waterbody such as marinas and wharfs, but also large projects such as dams or dykes. Dredging can be used to change the way the water moves in the landscape to reduce flood risk and free up more land, however these projects can have large impacts on the environment and therefore require careful planning.
Dredging can also be used to clean up a water body which has been silted up and blocked with decaying organic matter such as leaves or tree branches. In some cases, these waterbodies have very poor water quality due to the decaying processes which use up dissolved oxygen. This makes the environment unliveable for fish and other aquatic organisms. In other cases, contaminated sediment might be present, this needs to be removed and treated in order to return the good water quality to the area.
Lastly, a controversial advantage of dredging is the removal of valuable minerals. There has been research into using dredging to mine the ocean floor for valuable metals such as silver, gold, copper, manganese, cobalt and zinc. These are often present close to hydrothermal vents at great depths and many people consider these as a fantastic resource that’s yet to be used. In our opinion, the impact of dredging at such great depths is devastating to the local habitat which takes millennia to recover. We should focus on contributing to a circular economy and reusing materials we already use rather than deep-sea mining, however it is important to include it here for completeness.
To summarise, the benefits of dredging can be varied, and different locations require different techniques. We at Exo specialise in solving the most challenging dredging tasks and pride ourselves at achieving it all whilst having no impact or, more often, benefiting nature in the process. Check out our Dredging Consultancy services to find out more.