SUSPENDED PARTICLE DYNAMICS IN A WELL-MIXED ESTUARY: DEVIATIONS FROM MORPHODYNAMIC EQUILIBRIUM

Manuel Díez-Minguito, Miguel Ortega-Sánchez, Asunción Baquerizo, Huib E. de Swart, Miguel A. Losada

Abstract


This paper presents an analysis of turbidity and suspended sediment transport during low river flows in the Guadalquivir river estuary (Spain). The distribution and sources of the suspended particulate matter (SPM) are identified. The analysis of the transport rates allow us to devise a semi-analytical model for transport of SPM in well-mixed estuaries. The model solves the mass balance equation for SPM on a tidally-averaged timescale. The main inputs are the along channel transport rates and the vertical turbulent difusion cofecients at several locations. The model is applied to the Guadalquivir estuary, where a comprehensive monitoring network was installed from 2008 to 2011. Its application to this estuary allows to check how the SPM concentrations in different reaches of the estuary deviate from their equilibrium values. The results indicate that erosion is dominant in the stretches near to the mouth and that the estuary seems to move towards equilibrium during weak tidal forcing conditions.

Keywords


Guadalquivir Estuary, Suspended Sediment Transport; Estuarine Turbidity Maxima; Box Model; Morphodynamic Equilibrium

Full Text:

PDF

References


H. Burchard and H. Baumert. The formation of estuarine turbidity maxima due to density eects in the salt wedge. a hydrodynamic process study. Journal of Physical Oceanography, 28(2):309–321, 1998.

A. S. Chernetsky, H. M. Schuttelaars, and S. A. Talke. The eect of tidal asymmetry and temporal settling lag on sediment trapping in tidal estuaries. Ocean Dynamics, 60(5):1219–1241, 2010.

E. Contreras and M. Polo. Measurement frequency and sampling spatial domains required to characterize turbidity and salinity events in the guadalquivir estuary (spain). Natural Hazards and Earth System Science, 12(8):2581–2589, 2012.

M. Díez-Minguito, A. Baquerizo, M. Ortega-Sánchez, G. Navarro, and M. Losada. Tide transformation in the Guadalquivir estuary (SW Spain) and process-based zonation. Journal of Geophysical Research, 117 (C3):C03019, 2012.

M. Díez-Minguito, E. Contreras, M. Polo, and M. Losada. Spatio-temporal distribution, along-channel transport, and post-riverflood recovery of salinity in the Guadalquivir estuary (SW Spain). Journal of Geophysical Research, 118(5):2267–2278, 2013.

K. R. Dyer. Sediment transport processes in estuaries. Developments in Sedimentology, 53:423–449, 1995.

D. A. Jay and J. D. Musiak. Particle trapping in estuarine tidal flows. Journal of Geophysical Research, 99 (C10):20445–20461, 1994.

J. Lin and A. Y. Kuo. Secondary turbidity maximum in a partially mixed microtidal estuary. Estuaries, 24 (5):707–720, 2001.

G. Navarro, F. J. Gutierrez, M. Díez-Minguito, M. A. Losada, and J. Ruiz. Temporal and spatial variability in the Guadalquivir Estuary: A challenge for real-time telemetry. Ocean Dynamics, 61(6):753–765, 2011.

R. Pawlowicz, B. Beardsley, and S. Lentz. Classical tidal harmonic analysis including error estimates in MATLAB using T-TIDE. Computers & Geosciences, 28:929–937, 2002.

M. Reyes-Merlo, M. Díez-Minguito, M. Ortega-Sánchez, A. Baquerizo, and M. Losada. On the relative influence of climate forcing agents on the saline intrusion in a well-mixed estuary: Medium-term Monte Carlo predictions. Journal of Coastal Research, 65:1200–1205, 2013.

J. Ruiz, M. Polo, M. Díez-Minguito, G. Navarro, E. Morris, E. Huertas, I. Caballero, E. Contreras, and M. Losada. The Guadalquivir estuary: A hot spot for environmental and human conflicts in Advances in Coastal and Marine Resources: Remote Sensing and Modeling, (eds) Klein, A.H.F. and Finkl, C.W.

Springer, 2014. in press.

J. H. Simpson, J. Brown, J. Matthews, and G. Allen. Tidal straining, density currents, and stirring in the

control of estuarine stratification. Estuaries, 13(2):125–132, 1990.

S. A. Talke, H. E. de Swart, and V. N. de Jonge. An idealized model and systematic process study of oxygen depletion in highly turbid estuaries. Estuaries and coasts, 32(4):602–620, 2009.




DOI: https://doi.org/10.9753/icce.v34.sediment.78