Predicting the dynamics of intermittently closed/open estuaries using attractors

Hinwood, Jonathan Barry; McLean, Errol J

doi:10.1016/j.coastaleng.2015.02.008

Cited by 17 publications

(11 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Estuary entrance closure is a function of the relative balance between on and offshore sediment transport within the entrance channel (Fortunato et al ., ; Garside et al ., ; Hinwood and McLean, ) (Figure ). Closure occurs during periods of low river flow when wave‐driven onshore deposition surpasses the ability of ebb‐tidal currents to remove sediment from the channel (Gao and Collins, ; Morris and Turner, ; Whitfield et al ., ; Ranasinghe et al ., ).…”

Section: Introductionmentioning

confidence: 99%

The daily‐scale entrance dynamics of intermittently open/closed estuaries

McSweeney

Kennedy

Rutherfurd

2017

Earth Surf Processes Landf

View full text Add to dashboard Cite

Intermittently open/closed estuaries (IOCE) are a dynamic form of estuary characterised by periodic entrance closure to the ocean. Entrance closure is a function of the relative balance between on and offshore sediment transport with closures occurring during periods of low fluvial discharge whereby the estuary ebb‐tidal prism is reduced. Although the broad scale processes of entrance closure are becoming better understood, there remains limited knowledge on channel morphodynamics during an individual closure event. In this study, the entrance dynamics of three IOCE on the coast of Victoria, Australia, were monitored over a daily timescale following both artificial and natural openings. The influence of changing marine and fluvial conditions on the relative sedimentation rate within the entrance channel was examined. IOCE in Victoria showed two distinct modes of entrance closure: (a) lateral accretion, whereby the estuary gradually closes by longshore drift‐driven spit growth during low river flows; and (b) vertical accretion, where the channel rapidly aggrades under high (> 2 m), near‐normal waves. During storms, when fluvial discharge and wave heights simultaneously increase, large swells will not always close the mouth due to an increase in the ebb‐tidal prism. The estuary water depth and the maximum channel dimensions following opening were not proportional to the opening duration, with this being a function of the wave and fluvial conditions occurring following lagoon drainage. Based on the findings of this work, implementing a successful artificial entrance opening is dependent on reduced onshore sedimentation rates which occur when wave energy is low (< 2 m Hs) relative to river flow. Copyright © 2017 John Wiley & Sons, Ltd.

show abstract

Section: Introductionmentioning

confidence: 99%

The daily‐scale entrance dynamics of intermittently open/closed estuaries

McSweeney

Kennedy

Rutherfurd

2017

Earth Surf Processes Landf

View full text Add to dashboard Cite

show abstract

“…A set of model runs applies strictly to only one estuary. Typical values of the parameters for south‐eastern Australian barrier estuaries are given in Hinwood and McLean (); this data set enables one set of model runs to generate typical solutions for this group of estuaries.…”

Section: Methodsmentioning

confidence: 99%

Response of a barrier estuary to climate change and river regulation using attractor analysis: Snowy River estuary, Australia

McLean

Hinwood

Williams

2018

River Research & Apps

View full text Add to dashboard Cite

The evolution of the entrance channel of the Snowy River estuary in response to river regulation and climate change is predicted. The predictions are made in terms of the physical attractors that define possible long‐term states of the estuary entrance condition. The classification of these attractors shows the dependence of the entrance stability on the catchment inflows and the present entrance depth. The Snowy River estuary in south‐eastern Australia is a barrier estuary with an unstable entrance that tends to closure. The classification from the attractor map shows that the estuary entrance has changed from predominantly stable to a predominantly unstable state attributable to diversion of water from the upper catchment. The introduction of a series of environmental flow regimes, commencing in 2002, has returned 8% rising to 21% of the mean annual natural flow, but this study shows that the releases provide limited improvement in entrance stability. Additionally, the predicted effects of climate change for this region include increased mean sea level (MSL), decreased annual rainfall, and increased incidence of storms. These changes will decrease stability, primarily through the rise in MSL. The rise in sea level will increase the plan area of the tidal basin, increasing the tidal prism, and hence drawing in more marine sand. The application to the Snowy River estuary provides a proof of concept of the attractor classification to support estuary management.

show abstract

“…Each has formed over the past few thousand years, depending on the initial bedrock and inherited Pleistocene topography, through the supply of sediment from the catchment by rivers or creeks, together with incursion of marine sands through a tidally-influenced entrance (Roy 1984). The evolution process may be nonlinear and inconsistent (Hinwood and McLean 2015); at mature stages, the river and the tidal inlet start to connect with each other, but vertical sediment aggradation in the central mud basin appears to become inhibited by wind-wave processes (Adlam 2014). The evolution process may be nonlinear and inconsistent (Hinwood and McLean 2015); at mature stages, the river and the tidal inlet start to connect with each other, but vertical sediment aggradation in the central mud basin appears to become inhibited by wind-wave processes (Adlam 2014).…”

Section: Regional Settingmentioning

confidence: 99%

“…Successive stages from youthful to mature can be identified by the degree to which this underlying topography is infilled by the fluvial sediment input together with marine sands brought in by tidal processes (Roy et al 2001). The evolution process may be nonlinear and inconsistent (Hinwood and McLean 2015); at mature stages, the river and the tidal inlet start to connect with each other, but vertical sediment aggradation in the central mud basin appears to become inhibited by wind-wave processes (Adlam 2014). Wind-wave induced sediment redistribution processes affect the margin of the estuary, and could slow progradation of fluvial river deltas by dispersing sediments alongshore away from the river mouth.…”

Section: Regional Settingmentioning

confidence: 99%

Wind influence on the orientation of estuarine landforms: An example from Lake Illawarra in southeastern Australia

Deng

Jones

Rogers

et al. 2018

Earth Surf Processes Landf

View full text Add to dashboard Cite

We propose a type of a quasi‐equilibrium, which describes a convergence of the estuarine system towards a form whose planimetric orientation is along the prevailing winds. By using the microtidal Lake Illawarra in southeastern Australia as an example, we describe sediment convergent and divergent processes that induce such an equilibrium controlled by the complex configuration of the shoreline relative to the prevailing winds. For a complex estuarine sedimentary system with a mixture of non‐cohesive and cohesive sediments, alongshore distribution of fluvial or marine sand deposition and associated subaqueous morphology reflects alongshore redistribution of sediments from rivers and the tidal inlet. The orientation of the second‐order polynomial trend surface of estuarine morphology is consistent with prevailing wind directions. Along the lake shore, there are extensive narrow flats mainly covered by fluvial or marine sands shaped by the prevailing winds. The implementation of the Delft3D flow model coupled with the SWAN wave model driven by idealized prevailing winds indicates the potential of sediment convergent and divergent transport at the embayment and promontory shoreline, which appears to be similar to the alongshore distribution of sandy sediments and the nearshore flats. Alongshore transport of sandy sediments is primarily induced by the wave refraction on the shore, while the currents are more effective in transporting fine‐grained sediments such as mud or clay. Finally, we suggest a conceptual model that describes potential sediment transport of convergence and divergence on the embayment or promontory shoreline that is normal to the prevailing winds. Orientation of the estuary follows the convergence centre of sediment transport driven by the prevailing winds with the largest fetch. A quantitative threshold for such sediment redistribution may be determined in the future. © 2018 John Wiley & Sons, Ltd.

show abstract

Predicting the dynamics of intermittently closed/open estuaries using attractors

Cited by 17 publications

References 14 publications

The daily‐scale entrance dynamics of intermittently open/closed estuaries

The daily‐scale entrance dynamics of intermittently open/closed estuaries

Response of a barrier estuary to climate change and river regulation using attractor analysis: Snowy River estuary, Australia

Wind influence on the orientation of estuarine landforms: An example from Lake Illawarra in southeastern Australia

Contact Info

Product

Resources

About