Manly Hydraulics Laboratory

Sydney, Australia

Manly Hydraulics Laboratory

Sydney, Australia
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Young S.,Manly Hydraulics Laboratory | Couriel E.,Manly Hydraulics Laboratory | Jayewardene I.,Manly Hydraulics Laboratory | McPherson B.,Manly Hydraulics Laboratory | Dooley B.,Lake Illawarra Authority
Australian Journal of Civil Engineering | Year: 2014

Prior to completion of entrance improvements in 2007, Lake Illawarra behaved as an ICOLL (intermittently closed and open lakes and lagoons) with entrance conditions dependent on prevailing conditions. Since construction of twin training breakwaters and dredging in 2007, the entrance has remained permanently open, with water level stations within the estuary recording an increasing tidal signal. This paper provides a case study describing methods to assess the stability of the entrance to Lake Illawarra through preliminary analysis of aerial photography, hydro-survey, continuous water level records, consecutive tidal gauging and Escoffier analysis. Regarding the case study of entrance stability, consideration is given to data for analysis, limitations of the analysis and its reliance on local or site specific empirical data, needs for ongoing monitoring and tuning to represent further data, potential implications for Lake Illawarra and on similar estuaries and possible management responses. The likely effects of expected sea level rise on stability of the entrance are also estimated based on the understood key physical processes. Since completion of the entrance works, the lake is characterised by an 'unstable scouring' entrance as indicated by empirical analysis supported by lake water level and catchment rainfall data, tidal flow gauging, hydro-surveys and aerial photography. Ongoing monitoring and evaluation will determine further action that may be required. © Institution of Engineers Australia, 2014.


Jayewardene I.,Manly Hydraulics Laboratory | Couriel E.,Manly Hydraulics Laboratory
Coasts and Ports 2013 | Year: 2013

NSW Public Works' Manly Hydraulics Laboratory (MHL) has on several occasions utilised physical modelling and numerical modelling to estimate forces for design specifications of maritime structures. Often linear wave theory is utilised to estimate the accuracy of force measurement due to waves in a wave flume. The non-linearity of a wave and the appropriateness of the wave theory describing its behaviour are discussed in the literature by Dean [7]. In the case studies investigated parameters such as the Ursell number (HL 2/d3), H/T2 and d/T2 were utilised to categorise the non-linearity of the wave condition and appropriateness of the wave theory, the variables H, d and L representing wave height, water depth and wave length respectively. This paper investigates the differences in applying linear (Airy), higher order stream function wave theory and some widely used empirical functions to estimate wave force measurement.


Coad P.,Hornsby Shire Council | Cathers B.,University of New South Wales | Ball J.E.,University of Technology, Sydney | Kadluczka R.,Manly Hydraulics Laboratory
Environmental Modelling and Software | Year: 2014

Algae proliferate when favourable biological, chemical and physical conditions are present. Algal blooms within the Hawkesbury River, NSW, are a regular feature of seasonal cycles and develop in response to non-periodic disturbances. To improve the understanding of processes that lead to algal blooms, an autonomous buoy has been deployed (since 2002) which has generated a high resolution, temporal data set. Parameters monitored at 15min intervals include Chlorophyll-a, temperature (water and air), salinity and photosynthetically available radiation. This data set is used to configure an Artificial Neural Network (ANN) to predict (one, three and seven days in advance) the mean, 10th and 90th percentile, daily Chlorophyll-a concentrations. The prediction accuracy of the ANNs progressively decreased from one to seven days in advance. Incorporating predictive models coupled with near real time data sourced from automated, telemetered monitoring buoys enables environmental managers to implement proactive algal bloom management strategies. © 2014.


Coghlan I.,University of New South Wales | Mole M.,University of New South Wales | Shand T.,University of New South Wales | Carley J.,University of New South Wales | And 6 more authors.
20th Australasian Coastal and Ocean Engineering Conference 2011 and the 13th Australasian Port and Harbour Conference 2011, COASTS and PORTS 2011 | Year: 2011

Seven offshore wave buoys in the NSW coastal wave monitoring network have been deployed in water depths of 60 to 100 m to collect long-term wave data along the NSW coast. Previous studies have indicated that the mean and extreme wave heights measured at Byron Bay, Coffs Harbour, Crowdy Head, Sydney, Port Kembla and Eden are generally similar, but all are higher than the wave heights measured at Batemans Bay. This study investigated the causes of this disparity. Initially, the physical mechanisms which may influence the wave climate in the region were identified. The wave climate in the Batemans Bay region was then analysed in a two-part study based on the output of the Australian Bureau of Meteorology's HI-WAM model; a high resolution version of the ocean wave prediction model WAM. Part 1 of the study assessed the performance of HI-WAM. It was found that that the HI-WAM model was capable of reproducing the measured mean wave heights at all seven offshore locations on the NSW coast, including the reduced measured mean wave heights at Batemans Bay. Part 2 of the study determined how far offshore and alongshore this reduced wave climate extends. It was found that the alongshore variation in significant wave height is minor in the vicinity of Batemans Bay indicating that Batemans Bay wave buoy is, in general, representative of the nearshore region between Eden and Jervis Bay. However, there is a strong trend for significant wave height to increase with the shore-normal distance offshore under most conditions. This trend was found not to be attributable to ocean circulation currents or bottom friction, but due to land mass sheltering effects and wind field variations. The findings of this study indicate that maritime structures and activities planned for locations seaward of all the buoys in the NSW coastal wave monitoring network, not just the Batemans Bay buoy, should consider exposure to higher wave heights than that measured at each respective wave buoy.


Jayewardene I.F.W.,Manly Hydraulics Laboratory | Modra B.,Manly Hydraulics Laboratory | Campbell D.,Atteris Pty Ltd. | Chamizo D.,Atteris Pty Ltd.
20th Australasian Coastal and Ocean Engineering Conference 2011 and the 13th Australasian Port and Harbour Conference 2011, COASTS and PORTS 2011 | Year: 2011

Although empirical methods exist for the design of submerged rock berm structures, significant optimisation may be achieved through physical model testing. This paper outlines the 2D and 3D physical modelling undertaken to optimise the design berm dimensions and armour size for a berm structure required for protection of hydrocarbon pipelines. The return period conditions tested were based on combined wave orbital velocities at the bed and steady currents, which were both simulated in the Manly Hydraulics Laboratory (MHL) 2D flume. The 2D testing utilised model scales of 1:35 and 1:40 and the 3D testing utilised a scale of 1:35. In addition to optimising the rock grading, the influence of rock cover height was also investigated during the tests. Both regular waves and Pierson-Moskowitz spectra were utilised in the testing. This paper describes the test conditions and the scaling effects that would influence model results, particularly under 2D conditions. In the 3D testing the importance of accurately replicating bathymetry and an adjoining trench is discussed.


Taylor D.,Baird Australia | Garber S.,Baird Australia | Burston J.,Baird Australia | Couriel Ed.,Manly Hydraulics Laboratory | And 2 more authors.
Australian Coasts and Ports 2015 Conference | Year: 2015

A detailed understanding of spatial and temporal variability in oceanic and nearshore wave climates is essential to better assess the present and future risks of coastal hazards such as erosion and inundation. Previously, the Office of Environment and Heritage (OEH) have developed a NSW Coastal Ocean Wave Model System, comprising coupled WAVEWATCH-III and SWAN spectral wave models. That model system has been applied to develop long-term wave hindcast data sets, see [1] and [2], at offshore locations along the NSW coastline. However, due to the computational effort required to transfer the deep-water wave data sets to the shoreline, the process of dynamically simulating nearshore wave climates can only be carried out on a project-specific basis for selected locations at present. This paper presents three different methods for a Wave Transfer Function to transfer measured and hindcast (modelled) wave data from deep water across the continental shelf offshore of NSW to the nearshore. The WTF's have been calibrated with hindcast wave data from the WW-III nearshore model used to develop WTF's, and also measured WaveRider buoy data from two nearshore sites. Two spectral WTF methods were demonstrated to have excellent validation with the physics based WW-III hindcast model, and also good agreement with the measured nearshore WRB data. The computational requirement for all of the WTF's to develop a long-term wave hindcast along the NSW coastline is less than 2% of that required for the state-wide numerical WW-III model, demonstrating that the WTF approach provides an accurate and computationally efficient method to develop long term nearshore hindcast wave data along the whole NSW coastline.


Jacobs R.,Manly Hydraulics Laboratory | Jayewardene I.F.W.,Manly Hydraulics Laboratory | Couriel E.,Manly Hydraulics Laboratory | Modra B.,Manly Hydraulics Laboratory | And 3 more authors.
Coasts and Ports 2013 | Year: 2013

In 1993 Manly Hydraulics Laboratory (MHL) was commissioned to survey 63 river entrance training walls and breakwaters in New South Wales and provide a repair strategy for future remediation. The Coffs Harbour East breakwater was arguably the most exposed breakwater to be assessed. Since then MHL has from time to time assessed storm damage and made structural assessments of this breakwater. In 1998 MHL replicated in a 3D physical model extensive damage to the head due to the May 1997 storm and simulated a successful repair strategy. Prior to physical modelling the location of breaking waves during extreme wave conditions was assessed using a mild slope (REF/DIF) numerical model. A number of head repair strategies were also modelled and utilised in the 2001 repair when 28t Hanbar units replaced the 40t concrete cubes on the head. Subsequently MHL has been commissioned by the Department of Trade and Investment - Crown Lands to assess the general condition and storm damage of this breakwater. In 2012 MHL was commissioned to carry out 3D modelling to evaluate remediation design criteria for this breakwater.


Kulmar M.,Manly Hydraulics Laboratory | Modra B.,Manly Hydraulics Laboratory | Fitzhenry M.,Office of Environment and Heritage
Coasts and Ports 2013 | Year: 2013

Deepwater wave data is routinely collected for the NSW Office of Environment and Heritage by NSW Public Works' Manly Hydraulics Laboratory using a network of wave monitoring buoys. The data comprise longterm wave histories at seven locations along the 1200 kilometre NSW coastline. Data at four of the stations is available for periods of over 35 years and therefore represents one of the most comprehensive wave climate data sets available anywhere in the world. Since the Sydney station was upgraded with a Datawell Directional Waverider buoy in 1992, the buoy network has been progressively converted to directional buoys from 1999 to 2012. An overview of seasonal directional variations along the NSW coast and data rich directional spectra processed by the directional buoys will be presented for the first time. This information will be of great interest to coastal managers and designers, particularly with the increased awareness of the potential impact of climate change on regional wave climates. Predictions of increased storminess, changes to wave direction distributions and the potential impact on coastal processes highlight the need for the continued collection of ocean wave data into the future.


McPherson B.,Manly Hydraulics Laboratory | Young S.,Manly Hydraulics Laboratory | Modra B.,Manly Hydraulics Laboratory | Couriel E.,Manly Hydraulics Laboratory | And 5 more authors.
Coasts and Ports 2013 | Year: 2013

Flooding in the coastal waterways of New South Wales is rarely a function of just one source variable, therefore understanding the risk posed by the combined effect of two or more environmental variables such as waves, tide, storm surge, river flow, rainfall, swell and wind is important. This study aims to investigate the penetration behaviour of tides and tidal anomalies into estuaries in NSW. NSW Public Works' Manly Hydraulics Laboratory (MHL) and the University of Queensland (UQ), with input from the Office of Environment and Heritage (OEH), employed a number of different analysis techniques to investigate tides and tidal anomalies in NSW estuaries including harmonic analysis and HiLo analysis. The analysis techniques were used to investigate in detail the behaviour of tides and anomalies for a number of identified anomaly events at six key estuaries in NSW: Brunswick River, Hunter River, Lake Macquarie, Hawkesbury River, Lake Illawarra and Lake Conjola. These key estuaries were chosen due to their relative spread along the NSW coast and as typical representatives of the river, bay, lake and ICOLL estuary types.

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