Sediment transport processes in coastal lagoons
In: Kjerfve, B. (Ed.) (1994). Coastal lagoon processes. Elsevier Oceanography Series, 60. Elsevier: Amsterdam/Oxford/New York/Tokyo. ISBN 0-444-55556-0; e-ISBN 978-0-444-88258-5. XX, 577 pp., more In: Elsevier Oceanography Series. Elsevier: Oxford; New york; Amsterdam. ISSN 0422-9894, more |
| Abstract | A review of sediment transport in lagoons provides a better understanding of how processes act to modify, retain and accumulate sediment. The lagoon transport system is examined as a series of processes that distribute fine-grained sediment between sources and sinks. The processes cycle sediment from one part of a lagoon to another with small amounts being added intermittently from diverse sources to balance amounts removed from the system or that go into storage. Residual transport of fine suspended sediment is regulated by tidal pumping, shear transport or time-flow asymmetry. During transport and recycling, fine particles are modified by aggregation, break-up and reforming. After deposition, benthic fauna further modify the sediment by changing its stability, geotechnical properties, and erosion resistance. Additionally, wind waves winnow fines from shoals thus modifying textural characteristics, while tidal mechanisms have selective effects on the particle composition and size distributions. Lagoon sinks incorporate a number of fill components reflecting multiple sources and fluctuations in energy dissipation interacting on the sediment supply. Climate mainly influences the source material and the sediment character of intertidal zones. Although sediments are extensively modified, recycled and reworked, especially by storms, lagoons primarily function as net sediment sinks in which the accumulation rates adjust to submergence. Sediment processes are a crucial link to understanding the fate of materials in lagoons since they modulate the chemical reactivity and biological productivity of lagoons. Our knowledge, however, is still imperfect and sediment processes therefore warrant increased study and scrutiny. |
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