Measurement frequency and sampling spatial domains required to characterize turbidity and salinity events in the Guadalquivir estuary (Spain)

Contreras, Eva; Polo, María José

doi:10.5194/nhess-12-2581-2012

Cited by 26 publications

(16 citation statements)

References 16 publications

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“…The concentration of solids in suspension usually varies between 0.5 and 4:5kg=m 3 . Values at the nearsurface as high as 16kg=m 3 , triggered by discharges from the upstream dam, may also be found [Contreras and Polo, 2012].…”

Section: Study Areamentioning

confidence: 99%

Structure of the turbidity field in the Guadalquivir estuary: Analysis of observations and a box model approach

et al. 2014

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A study is presented on the transport of suspended particulate matter (SPM) in the Guadalquivir estuary during low river flow conditions. Observations show that tidally induced SPM exceeds that associated with catchment-derived inputs. The main mechanisms that contribute to longitudinal transport are identified and quantified by analyzing the tidally averaged and depthintegrated SPM flux decomposition over time and space. The net transport is generally directed upstream, although differences in the direction between spring and neap tides are identified. The transport is largely controlled by the mean advection, the tidal pumping associated with the covariance between SPM concentration and current, and the tidal Stokes transport. The convergence of the transport associated to these mechanisms alone explains the presence of primary and secondary estuarine turbidity maxima. The tidal reflection at the upstream dam appears to play a significant role in their generation, as evidenced by the convergence zones of the M4 and M2 induced tidal pumping transports. The spatial structure of the transport motivates the development of a box model that describes the concentration of SPM and its exchange between different stretches along the estuary at subtidal time scales. The model is fed by the net SPM transport obtained from observations. Analysis of the morphodynamical state of the estuary using the box model indicates that erosion is dominant in the stretches close to the estuary mouth and that this sediment is transported upstream and deposited in the middle part of the estuary. This process is more influential during spring tides than during neap tides.

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Section: Study Areamentioning

confidence: 99%

Structure of the turbidity field in the Guadalquivir estuary: Analysis of observations and a box model approach

et al. 2014

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“…The transitional periods of upstream migration and downstream flushing of the TMZ and of its associated mobile mud in fluvial sections have also not been detailed. These limitations are partly due to the absence of relevant long-term data sets, which are not so common in estuaries (Garel et al, 2009;Contreras and Polo, 2012).…”

Section: Introductionmentioning

confidence: 99%

Turbidity in the fluvial Gironde Estuary (southwest France) based on 10-year continuous monitoring: sensitivity to hydrological conditions

Jalón‐Rojas

Schmidt

Sottolichio

2015

Hydrol. Earth Syst. Sci.

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Abstract. Climate change and human activities impact the volume and timing of freshwater input to estuaries. These modifications in fluvial discharges are expected to influence estuarine suspended sediment dynamics, and in particular the turbidity maximum zone (TMZ). Located in southwest France, the Gironde fluvial-estuarine system has an ideal context to address this issue. It is characterized by a very pronounced TMZ, a decrease in mean annual runoff in the last decade, and it is quite unique in having a long-term and highfrequency monitoring of turbidity. The effect of tide and river flow on turbidity in the fluvial estuary is detailed, focusing on dynamics related to changes in hydrological conditions (river floods, periods of low discharge, interannual changes). Turbidity shows hysteresis loops at different timescales: during river floods and over the transitional period between the installation and expulsion of the TMZ. These hysteresis patterns, that reveal the origin of sediment, locally resuspended or transported from the watershed, may be a tool to evaluate the presence of remained mud. Statistics on turbidity data bound the range of river flow that promotes the upstream migration of TMZ in the fluvial stations. Whereas the duration of the low discharge period mainly determines the TMZ persistence, the freshwater volume during high discharge periods explains the TMZ concentration at the following dry period. The evolution of these two hydrological indicators of TMZ persistence and turbidity level since 1960 confirms the effect of discharge decrease on the intensification of the TMZ in tidal rivers; both provide a tool to evaluate future scenarios.

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“…The concentration of solids in suspension usually varies between 0.5 kg/m 3 and 4.5 kg/m 3 . Values at the near-surface as high as 16 kg/m 3 , triggered by discharges from the upstream dam, have been also found (Contreras and Polo, 2012). Time series analysis of CTD's measurements (triangles in Fig.…”

Section: A First Picturementioning

confidence: 67%

Suspended Particle Dynamics in a Well-Mixed Estuary: Deviations From Morphodynamic Equilibrium

Díez‐Minguito

Ortega-Sánchez

Baquerizo

et al. 2014

Int. Conf. Coastal. Eng.

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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 alongchannel transport rates and the vertical turbulent diffusion coefficients 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.

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Measurement frequency and sampling spatial domains required to characterize turbidity and salinity events in the Guadalquivir estuary (Spain)

Cited by 26 publications

References 16 publications

Structure of the turbidity field in the Guadalquivir estuary: Analysis of observations and a box model approach

Structure of the turbidity field in the Guadalquivir estuary: Analysis of observations and a box model approach

Turbidity in the fluvial Gironde Estuary (southwest France) based on 10-year continuous monitoring: sensitivity to hydrological conditions

Suspended Particle Dynamics in a Well-Mixed Estuary: Deviations From Morphodynamic Equilibrium

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