Dynamic plumes descend rapidly towards the seabed and then spread radially outward across the seabed as a dense plume, slowing with time and distance as the kinetic energy is spent overcoming friction. The bulk behaviour of the water-sediment mixture, rather than the settling velocity of the individual particles, is important (Winterwerp, 2002). As the settling velocity of a dynamic plume is relatively large, the zone of impact is relatively small.
Hence a deposit of fines is formed in the near vicinity of the ship.
Unlike the speculations by the concerned group that the plumes will spread over large areas and cause huge impacts.
Dredging Implementation and Monitoring
All options for monitoring and implementation will require ongoing data collection including through scientific research on dredging and the ecosystems it may impact. In the “no-dredging ” option, if the Government reject the dredging of the sea floor, it risks acquisition of baseline data knowledge generated by dredging for future projects.
Hence there is a need to continue collecting and assessing data on the risk elements associated with dredging so as to continuously develop a holistic sustainable environmental management plan for seafloor dredging.
Multi-sectoral platform of stake holders with Government on dredging should form a foundation for Joint monitoring of a project environmental management plan based on impacts and risks identified in the EIA submitted by NMP and other companies.
Impact monitoring would cover the project areas and similar non-project areas to control for confounding factors. The project proponent should be responsible for funding the implementation of this monitoring plan. The regulator, in addition to supervising implementation, must verify the data through independent monitoring, and compile and analyze the data with a view to identifying potential needs for amending the environmental management plan submitted by dredgers. Monitoring should focus not only on environmental aspects, but also encompass impacts on benthos recovery. Data gathered through the above processes will inform the regulator on the appropriateness of the current option to dredge the ocean floor.
In conclusion, the management of sea floor dredging mining in a fiscally, environmentally, and socially responsible manner in line with the precautionary principle requires a sophisticated regulatory regime and highly specialized technical expertise. And can only be achieved successfully with a well-coordinated Government sectors.
The current misunderstanding surrounding the issuance of the Environmental Clearance Certificate to NMP, indicates a need for establishment of a Joint Multi-sectoral Platform within Government At the moment the Namibian Government has ability and expertise to monitor and implement Environmental Management through its Environmental Management Act of 2007, and other laws. NMP should be allowed to dredge the ocean floor for collection of baseline data as an implementation to dredging and be monitored accordingly. And our Government has a task to industrialise the Namibian economy through mineral beneficiation such as phosphate for fertilizers that is required to revolutionise the agricultural industry. We need food security, lets dredge the ocean.
Mulife Siyambango is a local Industrial Geologist, with a Master of Science in Industrial Rocks and Minerals (Exeter), an MBA in strategic Management (Maastricht), and current part time student LLM-Natural Resource Law (Univ. Dundee). He is the Centre Director at Centre for Geosciences Research in Windhoek.