Plymouth is a historic coastal city in the UK with a long maritime tradition. Plymouth’s location and bustling waterfront make it a hub for shipping, naval activities, and tourism. However, to keep Plymouth’s waters navigable for commercial ships and leisure boats alike, dredging is an essential part of maintaining the harbour.
Why Does Plymouth Need Dredging?
Plymouth’s geography is part of the reason dredging is critical. The city’s harbour and surrounding waterways are prone to natural sediment build-up. Over time, this reduces the water depth, making it harder for large ships to dock. Since Plymouth is home to both a commercial port and a naval base, the ability to accommodate large vessels is essential for both economic and defence reasons.
Without dredging, Plymouth’s docks and shipping lanes could become impassable, which would be a major blow to industries and businesses that rely on these waterways.
The Environmental Impacts of Dredging in Plymouth
While dredging is necessary, it doesn’t come without consequences. Environmental groups and marine scientists have raised concerns about how dredging can affect local ecosystems, particularly in sensitive coastal areas like Plymouth Sound, which is a designated Marine Protected Area.
Some potential impacts include:
- Disruption of Marine Habitats: When sediment is stirred up during dredging, it can disturb marine life, particularly bottom-dwelling species like fish and crustaceans. This can lead to habitat loss or shifts in the local marine ecosystem.
- Water Quality: Dredging can cause an increase in turbidity (cloudiness in the water), which can affect the health of marine species and disrupt feeding and breeding patterns. Suspended sediments may also carry pollutants that settle on the seabed, posing a threat to marine life.
- Noise Pollution: The machinery used in dredging operations can create underwater noise that disrupts marine mammals like dolphins and seals, which are present in the waters around Plymouth.
- Long-Term Changes: In some cases, dredging can lead to long-term changes in the sediment distribution and water currents, which might affect the overall health of the marine ecosystem in unexpected ways.
Mitigating the Impacts
Luckily, modern dredging techniques and environmental regulations have advanced to minimise these effects. Plymouth’s dredging projects are closely monitored to ensure they don’t exceed acceptable environmental limits. In an effort to further reduce environmental impact, RIG Plymouth aims to accept 400,000 cubic meters of dredged material per year once fully operational. This initiative prevents the sediment from being disposed of at sea, where it could potentially disrupt marine habitats and water quality.
By processing and storing the sediment on land, the region can avoid the harmful effects associated with offshore disposal, such as increased turbidity and contamination risks to marine life. Additionally, this material can be repurposed for beneficial use in land reclamation projects or for construction, helping to protect coastal areas from erosion while reducing the overall environmental footprint of dredging.
Information Sources
https://www.sciencedirect.com/science/article/abs/pii/S0079661115000865
https://www.annualreviews.org/content/journals/10.1146/annurev.ecolsys.33.010802.150515
https://www.sciencedirect.com/science/article/abs/pii/S1001074209600966