Methods for accurate estimation of net discharge in a tidal channel

Simpson, Michael R.; Bland, R.W.

doi:10.1109/48.895351

Cited by 36 publications

(21 citation statements)

References 2 publications

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“…A difficulty in flux estimation of this kind lies in the identification and correction of small systematic biases that are not easily removed through time averaging (Simpson and Bland 2000). In the case of the Blyth, it is possible to Fig.…”

Section: Sediment Flux Estimationmentioning

confidence: 99%

“…Knowledge of the sediment regime is increasingly relevant for the management and restoration of estuarine ecosystems (e.g., Goodwin et al 2001;Chen et al 2005), monitoring of contaminant inventories (Schoellhamer 1996;Spencer 2002;Robert et al 2004), and the prediction of estuary response to environmental change (e.g., Corbett et al 2007). Translation of recent advances in the understanding of estuarine sediment dynamics into robust flux and budget estimates remains problematic given the range of scales of tidal, fluvial, and meteorological forcing and the difficulty of isolating a small residual flux from much larger flood and ebb transports (Lane et al 1997;Simpson and Bland 2000;Townend and Whitehead 2003). Some of the more compelling analyses combine historic sedimentation information with instrumentation-derived sediment flux, possibly supported by physically based numerical modeling (e.g., Baird et al 1987).…”

mentioning

confidence: 98%

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Tidal and Meteorological Forcing of Suspended Sediment Flux in a Muddy Mesotidal Estuary

French

Burningham

Benson

2008

Estuaries and Coasts

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Although the supply and fate of suspended sediment is of fundamental importance to the functioning and morphological evolution of muddy estuaries, reliable sediment budgets have been established in only a few cases. Especially for smaller estuaries, inadequate bathymetric surveys and a lack of intertidal sedimentation data often preclude estimation of the sediment budget from morphological change, while instrument-derived residual fluxes typically lie well within the errors associated with measurement of much larger gross tidal transports. Given suitably long-term records of continuously monitored suspended sediment concentration (SSC), however, analysis of the major scales of variation in sediment transport and their relation to hydrodynamic and meteorological forcing permits qualitative testing of hypotheses suggested by directly measured residual fluxes. This paper analyzes data from a 1-year acoustic Doppler profiler deployment in the Blyth estuary, a muddy mesotidal barrier-enclosed system on the UK east coast. Flux calculations indicate a small sediment import equivalent to just 1.5% of the gross flood tide transport. Little confidence can be assigned to either the magnitude or direction of such a small residual when considered in isolation. However, the inference that the sediment regime is finely balanced is qualitatively supported by the close similarity between floodtide and ebb-tide SSC values. Singular spectrum analysis of the SSC time series shows the expectedly large contributions to the variance in SSC at intratidal and subtidal (semimonthly and monthly) scales but also picks out intermittent variability that is initially attributed to a combination of non-tidal surge and wind stress forcing. Closer examination of the data through cross-correlograms and event-scale analysis indicates that local meteorological forcing is the major factor. Acting through the resuspension of intertidal mudflat sediments at times of strong westerlies, meteorological forcing is directly implicated in episodic sediment export from the estuary. Thresholding of tide-averaged fluxes using a range of critical wind stress values further indicates that 'tide-dominated' (i.e., low wind stress) and 'wave-dominated' (high wind stress) conditions are associated with sediment import and export. Sediment balance is potentially sensitive to the frequency of high wind stress events, since the associated sediment exports are several times larger than the average import under calm conditions. Intermittent meteorological forcing may thus exert an important control on the sedimentary balance of otherwise tidally dominated muddy estuarine systems, and the role of wind climate should not be overlooked in studies of estuary response to environmental change.

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Section: Sediment Flux Estimationmentioning

confidence: 99%

mentioning

confidence: 98%

Tidal and Meteorological Forcing of Suspended Sediment Flux in a Muddy Mesotidal Estuary

French

Burningham

Benson

2008

Estuaries and Coasts

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“…In more complicated situations, such as tidal channel networks or very large estuaries, acoustic technologies have become the standard measurement method. Simpson and Oltmann (1993) and Simpson and Bland (2000) first detailed the use of shipboard acoustic Doppler current profilers (ADCPs) to calculate tidally varying discharge in estuarine channels; Ruhl and Simpson (2005) further described methods to generate continuous timeseries of tidal water fluxes in tidal channels. While these methods are accurate for instantaneous tidal water fluxes, extracting the residual flux due to freshwater flux alone can be difficult because of the small ratio of freshwater flux to instantaneous tidal flux (Ganju and Schoellhamer 2006).…”

Section: Quantification Of Tidal Water Fluxes and Total Exchange Flowmentioning

confidence: 99%

Tidal and Groundwater Fluxes to a Shallow, Microtidal Estuary: Constraining Inputs Through Field Observations and Hydrodynamic Modeling

Ganju

Hayn

Chen

et al. 2012

Estuaries and Coasts

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Increased nutrient loading to estuaries has led to eutrophication, degraded water quality, and ecological transformations. Quantifying nutrient loads in systems with significant groundwater input can be difficult due to the challenge of measuring groundwater fluxes. We quantified tidal and freshwater fluxes over an 8-week period at the entrance of West Falmouth Harbor, Massachusetts, a eutrophic, groundwater-fed estuary. Fluxes were estimated from velocity and salinity measurements and a total exchange flow (TEF) methodology. Intermittent cross-sectional measurements of velocity and salinity were used to convert point measurements to cross-sectionally averaged values over the entire deployment (index relationships). The estimated mean freshwater flux (0.19 m 3 /s) for the 8-week period was mainly due to groundwater input (0.21 m 3 /s) with contributions from precipitation to the estuary surface (0.026 m 3 /s) and removal by evaporation (0.048 m 3 /s). Spring-neap variations in freshwater export that appeared in shorter-term averages were mostly artifacts of the index relationships. Hydrodynamic modeling with steady groundwater input demonstrated that while the TEF methodology resolves the freshwater flux signal, calibration of the indexsalinity relationships during spring tide conditions only was responsible for most of the spring-neap signal. The mean freshwater flux over the entire period estimated from the combination of the index-velocity, index-salinity, and TEF calculations were consistent with the model, suggesting that this methodology is a reliable way of estimating freshwater fluxes in the estuary over timescales greater than the springneap cycle. Combining this type of field campaign with hydrodynamic modeling provides guidance for estimating both magnitude of groundwater input and estuarine storage of freshwater and sets the stage for robust estimation of the nutrient load in groundwater.

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“…En ríos mareales de agua dulce sin intrusión salina significativa, los perfiles de velocidad medidos en forma continua con un ADCP horizontal suelen relacionarse con el flujo medio aproximando la velocidad cerca del fondo con una ley de potencia o una logarít-mica [7,8]. No obstante, gradientes de salinidad significativos [9] o concentraciones excesivas de sedimentos [10] pueden entorpecer las mediciones, limitando la utilidad de los ADCP cerca de la desembocadura.…”

Section: Introductionunclassified

Estimación del caudal a partir de la evolución del nivel del agua en un estuario con onda de marea estacionaria

Thomas

Marino

2016

Ribagua

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Methods for accurate estimation of net discharge in a tidal channel

Cited by 36 publications

References 2 publications

Tidal and Meteorological Forcing of Suspended Sediment Flux in a Muddy Mesotidal Estuary

Tidal and Meteorological Forcing of Suspended Sediment Flux in a Muddy Mesotidal Estuary

Tidal and Groundwater Fluxes to a Shallow, Microtidal Estuary: Constraining Inputs Through Field Observations and Hydrodynamic Modeling

Estimación del caudal a partir de la evolución del nivel del agua en un estuario con onda de marea estacionaria

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