Resuspension of sediment in a semi-sheltered bay due to wind waves and fast ferry wakes

• Published in: Boreal environment research Vol. 16; p. 149
• Main Authors: Erm, A, Alari, V, Lips, I, Kask, J
• Format: Journal Article
• Language: English
• Published: Helsinki Finnish Environment Institute 2011
• ISSN: 1239-6095; 1797-2469

Concurrently with the wind wave induced sediment recycling, large sections of the coast of Tallinn Bay are influenced by wakes generated by high speed vessels. Based on in situ measurements of surface waves, underwater irradiance and the fluxes of resuspended sediment, combined with counting of particles with FlowCAM and numerical modeling of wind waves, it is shown, that the anthropogenic resuspension plays a key role in the western part of Tallinn Bay during the relatively calm spring and summer seasons. The near bottom orbital velocities generated daily by fast ferries’ wakes are equivalent to those induced by wind waves excited by at least 18 m s–1 southwestern winds and 12 m s–1 northern winds. About 400 kg of sediment is resuspended and carried away from each meter of coastline annually.