Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.1/10914
Título: Effects of the Alqueva dam on sediment fluxes at the mouth of the Guadiana Estuary
Autor: Garel, Erwan
Óscar, Ferreira
Data: 2011
Editora: Coastal Education and Research Foundation
Resumo: The exchange (import, export) of sediment near the mouth of the Guadiana Estuary during periods of damregulated and non-regulated river flow are computed and compared. Bedload and suspended sediment transport rates were derived from Acoustic Doppler Profiler (ADP) measurements at a fixed station (~2 years) and across the estuarine channel (3 tidal cycles). Suspended sediment concentrations (SSC) were obtained from water sampling during one of the tidal cycle surveys, and from turbidity measurements used to calibrate the ADP echo level at the fixed station. For low river flows, the net bedload transport was down-estuary at springs, yielding an estimate of 5,400 m3 yr-1 of export seaward. The vertical shear was enhanced for higher river flows, and favoured the upstream currents near the bed. Hence, the sand transport rates were similar to those predicted for low river flows. Significantly larger volumes of sand are exported only if the river discharge is large enough for freshwater to occupy the entire estuary. For low river flows, suspended sediment was imported at neaps and exported at springs, and the net transport was balanced over the long term. Significant export took place during moderately high discharge events. However, the transport of suspended sediment was several orders of magnitude lower than before flow regulation.
Peer review: yes
URI: http://hdl.handle.net/10400.1/10914
ISSN: 0749-0208
Aparece nas colecções:CIM2-Artigos (em revistas ou actas indexadas)

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