Effect of hydrodynamics factors on sediment flocculation processes in estuaries

Mhashhash, Aisha, Bockelmann-Evans, Bettina ORCID: https://orcid.org/0000-0003-4208-9341 and Pan, Shunqi ORCID: https://orcid.org/0000-0001-8252-5991 2018. Effect of hydrodynamics factors on sediment flocculation processes in estuaries. Journal of Soils and Sediments 18 (10) , pp. 3094-3103. 10.1007/s11368-017-1837-7

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Abstract

Purpose Cohesive sediment is able to flocculate and create flocs, which are larger than individual particles and less dense. The phenomenon of flocculation has an important role in sediment transport processes such as settling, deposition and erosion. In this study, laboratory experiments were performed to investigate the effect of key hydrodynamic parameters such as suspended sediment concentration and salinity on floc size and settling velocity. Results were compared with previous laboratory and field studies at different estuaries. Materials and methods Experimental tests were conducted in a 1-L glass beaker of 11-cm diameter using suspended sediment samples from the Severn Estuary. A particle image velocimetry system and image processing routine were used to measure the floc size distribution and settling velocity. Results and discussion The settling velocity was found to range from 0.2 to 1.2 mm s−1. Settling velocity changed in the case of increasing suspended sediment concentration and was controlled by the salinity. The faster settling velocity occurred when sediment concentration is higher or the salinity is lower than 2.5. On the other hand, at salinities higher than 20, in addition to increasing SSC, it was found that the situation was reversed, i.e. the lower the sediment concentration, the faster the settling velocity. Conclusions Sediment flocculation is enhanced with increasing sediment concentration but not with increasing salinity.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Engineering
Publisher:	Springer Verlag
ISSN:	1439-0108
Date of First Compliant Deposit:	3 October 2017
Date of Acceptance:	17 September 2017
Last Modified:	06 May 2023 05:51
URI:	https://orca.cardiff.ac.uk/id/eprint/105157

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