Process Contribution to the Time-Varying Residual Circulation in Tidally Dominated Estuarine Environments

Brown, Jennifer M.; Bolaños, Rodolfo; Souza, Alejandro J.

doi:10.1007/s12237-013-9745-6

Cited by 11 publications

(6 citation statements)

References 39 publications

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“…A Chebyshev type II, low-pass filter is applied to the residual surge component to remove all energy at tidal frequencies, using a stop-band of 26-h and a pass-band of 30-h (cf. [ 50 ]). The method separates out the time-varying meteorological residual and the tide-surge interactions, which will have been removed by the filter since it is frequency-dependent [ 50 ], to leave only the long period surge component.…”

Section: Methodsmentioning

confidence: 99%

“…[ 50 ]). The method separates out the time-varying meteorological residual and the tide-surge interactions, which will have been removed by the filter since it is frequency-dependent [ 50 ], to leave only the long period surge component. Atmospheric forcing is not included to restrict the sensitivity analysis to tide-surge propagation, without the complication of a locally generated surge contribution.…”

Section: Methodsmentioning

confidence: 99%

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Uncertainty in estuarine extreme water level predictions due to surge-tide interaction

et al. 2018

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Storm surge is often the greatest threat to life and critical infrastructures during hurricanes and violent storms. Millions of people living in low-lying coastal zones and critical infrastructure within this zone rely on accurate storm surge forecast for disaster prevention and flood hazard mitigation. However, variability in residual sea level up-estuary, defined here as observed sea level minus predicted tide, can enhance total water levels; variability in the surge thus needs to be captured accurately to reduce uncertainty in site specific hazard assessment. Delft3D-FLOW is used to investigate surge variability, and the influence of storm surge timing on barotropic tide-surge propagation in a tide-dominant estuary using the Severn Estuary, south-west England, as an example. Model results show maximum surge elevation increases exponentially up-estuary and, for a range of surge timings consistently occurs on the flood tide. In the Severn Estuary, over a distance of 40 km from the most upstream tide gauge at Oldbury, the maximum surge elevation increases by 255%. Up-estuary locations experience short duration, high magnitude surge elevations and greater variability due to shallow-water effects and channel convergence. The results show that surge predictions from forecasting systems at tide gauge locations could under-predict the magnitude and duration of surge contribution to up-estuary water levels. Due to the large tidal range and dynamic nature of hyper-tidal estuaries, local forecasting systems should consider changes in surge elevation and shape with distance up-estuary from nearby tide gauge sites to minimize uncertainties in flood hazard assessment.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Uncertainty in estuarine extreme water level predictions due to surge-tide interaction

et al. 2018

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“…This way, any tide-surge interaction remains within this residual surge component. A Chebyshev type II, low pass filter is applied to the residual surge component to separate out the time-varying meteorological residual and the tide-surge interactions (an approach used by Brown et al 2014). The low pass filter is designed to remove all energy at tidal frequencies, using a stop-band of 26 h and a pass-band of 30 h. A 3 dB pass-band ripple and 30 dB stop-band attenuation was used, to leave only the meteorological residual (low-frequency surge component with no tidal energy or tide-surge interaction) in the time series.…”

Section: Surge Characteristicsmentioning

confidence: 99%

“…The low pass filter is designed to remove all energy at tidal frequencies, using a stop-band of 26 h and a pass-band of 30 h. A 3 dB pass-band ripple and 30 dB stop-band attenuation was used, to leave only the meteorological residual (low-frequency surge component with no tidal energy or tide-surge interaction) in the time series. Tidal energy and tidal interaction is removed, as it has a similar frequency to the tide and leaves only the lowfrequency (> 30 h, sub-tidal) residual (Brown et al 2014). The low pass filter approach was validated using the 25 h running mean of the surge component.…”

Section: Surge Characteristicsmentioning

confidence: 99%

Flood Hazard Assessment for a Hyper-Tidal Estuary as a Function of Tide-Surge-Morphology Interaction

Lyddon

Brown

Leonardi

et al. 2018

Estuaries and Coasts

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Astronomical high tides and meteorological storm surges present a combined flood hazard to communities and infrastructure. There is a need to incorporate the impact of tide-surge interaction and the spatial and temporal variability of the combined flood hazard in flood risk assessments, especially in hyper-tidal estuaries where the consequences of tide and storm surge concurrence can be catastrophic. Delft3D-FLOW is used to assess up-estuary variability in extreme water levels for a range of historical events of different severity within the Severn Estuary, southwest England as an example. The influence of the following on flood hazard is investigated: (i) event severity, (ii) timing of the peak of a storm surge relative to tidal high water and (iii) the temporal distribution of the storm surge component (here in termed the surge skewness). Results show when modelling a local area event severity is most important control on flood hazard. Tide-surge concurrence increases flood hazard throughout the estuary. Positive surge skewness can result in a greater variability of extreme water levels and residual surge component, the effects of which are magnified up-estuary by estuarine geometry to exacerbate flood hazard. The concepts and methodology shown here can be applied to other estuaries worldwide.

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“…This is the why the two-layer system remains evident over the majority of the study period (eg. Brown et al, 2014).…”

Section: Currents and Wave-induced Currentsmentioning

confidence: 99%

Wave–current interactions in a tide dominated estuary

Bolaños¹,

Brown²,

Souza³

2014

Continental Shelf Research

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There is a need to understand the interactions of waves and currents in the nearshore and estuarine areas. By using observational data and an advanced model an assessment of the wavecurrent interactions was performed in a hypertidal estuary. The circulation model includes both barotropic and baroclinic processes arising from tides, rivers and atmospheric forcing. It is coupled to a spectral wave model and a turbulence model. Waves within the estuary are strongly modulated by the tide. Significant wave height and period are mainly controlled by time-varying water depth, but wave periods are also affected by a Doppler shift produced by the current. The major-axis depth-averaged current component is tidally dominated and wave induced processes do not have a significant effect on it. However, the inclusion of wave effects, in particular 3D radiation stress, improves the depth-averaged minor-axis (transverse) current component. The residual currents show a clear two-layer system, indicating that the baroclinic river influence is the dominant process. The wave effects are second order, but their consideration improves the long-term modelled residual circulation profile, specially the along estuary component. The main improvement appears when a 3-dimensional radiation stress coupling is considered. The 3D version of radiation stress produced better results than the 2D version. Within the estuary, wave setup has little effect on the storm surge, while 2-way wave-current interaction improved the wave simulation. Using a 3D Doppler shift further improved the model compared with using a 2D version.

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Process Contribution to the Time-Varying Residual Circulation in Tidally Dominated Estuarine Environments

Cited by 11 publications

References 39 publications

Uncertainty in estuarine extreme water level predictions due to surge-tide interaction

Uncertainty in estuarine extreme water level predictions due to surge-tide interaction

Flood Hazard Assessment for a Hyper-Tidal Estuary as a Function of Tide-Surge-Morphology Interaction

Wave–current interactions in a tide dominated estuary

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