Measuring the effects of dredging in relation to the dynamics of nature
Type:
Presented during:
CEDA Dredging Days 2009 - Dredging Tools for the Future, Rotterdam
Authors:
Koomans RL and Limburg J - Medusa Explorations, The Netherlands
Abstract: The discharge of fines during dredging and the impact of these fines on seafloor habitats is an important aspect in environmental impact assessments. Our vision is that the effects of dredging on the environment, should be related to the impact of the dynamics of nature itself.
The potential effects from sediment plumes on the seafloor sediments can only be understood when the total release of fine sediments from the overflow can be related to the natural variation in concentrations of fines in seafloor sediments. Today, the buffering capacity of the seafloor for fine sediments has been estimated, but has hardly been measured. The natural variation of fines and thereby the buffering capacity of the seafloor can be monitored and natural dynamics due to resuspension and large-scale sediment transport patterns can be quantified. The sediments released from the overflow of a hopper dredger are composed of sand and fine silts.
Since the sands will behave completely different to the fines, information on the total volume of fine material from the overflow is an important parameter. The release of fine material from a hopper overflow during dredging can be measured. With this quantification of sediment release, and the information of the buffering capacity of the seafloor sediments, the net effect of the release of fines during dredging can be related to the dynamics of nature.
Keywords: Sediment composition, monitoring, sediment density, sediment plume