Non-linear dynamics and attractors for the entrance state of a tidal estuary

Hinwood, Jonathan Barry; McLean, Errol J; Wilson, B. C.

doi:10.1016/j.coastaleng.2011.11.007

Cited by 12 publications

(25 citation statements)

References 18 publications

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“…We also note that if T tide is fixed, so that ˆt relationships are based on an important parameter -inlet tidal prism, presenting 'tidal force', while many researchers pointed out that tidal period, river flow, wave energy, sediment supply, etc need to be taken into account in these relations. Besides, the explanation of cross sectional stability or inlet closure is also reviewed based on Escoffier's (1940) Kraus (1998) or an 'ocean sediment concentration ' Hinwood et al (2012) and imply that stronger waves means smaller A. It also supports for the relationship, A eq = a 1 P eq n with exponent n<1 in previous studies.…”

Section: 1 or Perhaps Just N≈1supporting

confidence: 52%

“…Hume & Herdendorf (1993) derive reliable relationship so that it can be used to evaluate the cross-sectional stability of tidal inlets, which is mentioned in the next Section. Stive et al (2012) and Hinwood et al (2012) found that the equilibrium cross sectional area of much smaller inlets is larger than A estimated from the typical A eq~Peq . A eq does, no doubt, not depend on P eq exclusively.…”

Section: Historical Equilibrium Relationshipsmentioning

confidence: 99%

“…There are some simple robust models such as Hoan et al (2011 and Hinwood et al (2012) as reviewed in Section 6.2. However, they are not applicable for this case.…”

Section: Evolution Of the Throat Areamentioning

confidence: 99%

“…The analytical model for the evolution of inlet cross-section area by Larson et al (2011) was applied for a simple case of barrier breaching due to river run off without considering tidal flow. Hinwood et al's (2012), simple one dimensional process-based model, used 'ocean sediment concentration -C O '…”

Section: Evolution Of the Throat Areamentioning

confidence: 99%

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Aspects of inlet geometry and dynamics

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This thesis contains new analytical approaches as well as laboratory-and field experiments conducted to understand the hydrodynamic and morphodynamic responses of tidal inlets to forcing from tides, river flow and waves on the time scales of closure, flood or storm events. The thesis outcome is effective new tools for authorities managing coastal zones balancing navigation-, shore protection-and socio-economic development purposes.A new method of coastal inlet classification based on dimensionless parameters is presented. These parameters represent the relative strength of the three main forcing agents: tides, river flow and waves. This new classification is applied to 178 inlets along the NSW coast of Australia, and compared with other widely used classification schemes available in the literature.The inlet hydraulic analysis is presented in Chapter 2 with given inlet geometry and wave climate with overwash discharge (Q over ) added into the usual governing equations. The hydraulic analysis of inlets in terms of the frequency response function for the linearised system is illustrated for cases of monochromatic and mixed diurnal/semi-diurnal tides. This analysis quantifies the influence of the entrance invert level, river flow and bay surface area. A case of inland flooding at Lake Conjola, Australia is used to test different methods resulting in a successful illustration of the importance of wave overwash as a driving force.For each hydrodynamic condition, the inlet system and its elements have a corresponding morphological equilibrium state. New relationships for inlets in equilibrium were constructed based on dimensional analysis and tested on a data set of 36 natural inlets in the USA. These new relations depend not only on the tidal prism but also the tidal period, and mean annual significant wave height s H .During unusual weather, the morphology of tidal inlets runs out of equilibrium.Subsequently, they may return to the previous equilibrium or move towards a new equilibrium or get closed. Inlet morphodynamics analysis is ideally carried out from topographical surveys. These are however costly and usually not available. Process based numerical models are still unreliable. A more economical and reliable new method, a 24.5hour moving window method, is introduced to infer hydraulic-and morpho-dynamic changes from tidal records. The morphological time scales are thus determined from time series of mean water levels, standard deviation, or the gain of the primary tidal components. This analytical method is successfully applied to inlet closure events and flood or storm events.The morphological time scale, T morph has been derived from the 24.5hour moving window analysis for many closure events with bay area (A b <0.7km 2 ) in Australia. The results show a clear trend of T morph decreasing with increasing relative wave strength -i.e., more rapid closure with iii bigger waves. However, for larger inlets or inlets with training works the morphology changes, at the time scale of individual storms, are usua...

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Section: 1 or Perhaps Just N≈1supporting

confidence: 52%

Section: Historical Equilibrium Relationshipsmentioning

confidence: 99%

“…There are some simple robust models such as Hoan et al (2011 and Hinwood et al (2012) as reviewed in Section 6.2. However, they are not applicable for this case.…”

Section: Evolution Of the Throat Areamentioning

confidence: 99%

Section: Evolution Of the Throat Areamentioning

confidence: 99%

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Aspects of inlet geometry and dynamics

Vu¹

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“…In a dimensional analysis of the entrance stability, Bruun and Gerritsen added river inflow to the tidal prism, but then omitted it in their quantitative developments. These and later studies are reviewed in Hinwood et al (2012).…”

Section: Early Studies Of Stabilitymentioning

confidence: 98%

Predicting the dynamics of intermittently closed/open estuaries using attractors

Hinwood

McLean

2015

Coastal Engineering

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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

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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.

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Non-linear dynamics and attractors for the entrance state of a tidal estuary

Cited by 12 publications

References 18 publications

Aspects of inlet geometry and dynamics

Aspects of inlet geometry and dynamics

Predicting the dynamics of intermittently closed/open estuaries using attractors

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

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