Clare Weir, completed in 1978, is situated on the Burdekin River some 50 kms from the mouth near Ayr in North Queensland.
A fish ladder was built on the right bank as part of the original construction but observations of the fishway’s performance over a number of years and more recently by the Queensland Fisheries Service (QFS) have established that the fishway is not functioning as well as had been expected. Sampling upstream of the weir has shown a distinct reduction in both fish numbers and fish species.
Since 1997, a number of studies have been undertaken to examine options for improving the fishway performance. The outcome of the studies concluded that the installation of a fish lock clearly represented the best means of improving fish transfer performance at the weir.
This paper presents the various options investigated and outlines how the new fish lock will be integrated into the existing weir structure.
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Wivenhoe Dam is being upgraded to safely manage any conceivable flood in response to a revision of rainfall predictions by the Bureau of Meteorology. These revisions have led to a substantial increase in estimates of the Probable Maximum Flood that the storage must be able to manage under the ANCOLD guidelines. Wivenhoe Dam, completed in 1985, is located about 80 km north west of Brisbane and is the major domestic water supply for South East Queensland.
The dam is owned and operated by SEQWater who are responsible also for North Pine and Somerset Dams. The upgrade is being undertaken as an Alliance contract with the member companies being SEQWater, Leighton Contractors, MWH, Department of Commerce NSW, and Coffey Geosciences. The upgrade involves construction of a second spillway, 165 m wide on the right abutment. This will be a fuse plug spillway requiring excavation of approximately 600,000 m3 of material.
Construction impacts on the community include noise and dust, blasting, and temporary road diversions/lane closures of the main Brisbane Valley Highway over about two years of construction.
This paper deals with a wide range of stakeholder, community consultation and environmental initiatives that have involved local residents, stakeholders and recreational users in the planning and implementation phases of this project. Several long-term environmental legacies are also discussed.
Geoscience Australia, the Australian National Committee on Large Dams (ANCOLD), and Environmental Systems & Services (ES&S) are collaborating on a project to develop earthquake ground-motion models to improve earthquake hazard and risk assessments in Australia. Here we discuss the importance of such models, which have the potential to substantially reduce uncertainties in estimates of earthquake hazard and risk. This problem is important for Australia, where the lack of ground-motion data and models means that the uncertainty in predicted ground-motion is the dominant factor that controls uncertainty in risk and hazard assessments.
Progress thus far consists in analysing a dataset comprising some 400 seismograph and accelerograph records for 67 events from the Burakin 2001-02 earthquake swarm. Events range in size from moment magnitude 2.2 ≤ M ≤ 4.5. These data were compiled to develop a regional ground-motion model for the Yilgarn Craton, southwestern Western Australia (WA). Modelled horizontal-component spectral displacement amplitudes fit the observed data well. Amplitude residuals (predicted – observed amplitudes) are, on average, relatively small and do not vary significantly with distance from the earthquake.
Since these data were recorded from an earthquake swarm, we have reason to suspect that the spectral shapes observed may not be characteristic of isolated crustal earthquakes, particularly at low magnitudes. Our ground-motion model may therefore have limited application for predicting ground-motions for other earthquakes, particularly at periods less than 0.5 s. This gives added impetus for the need to include more data in our work and to expand this research into different seismotectonic regions within the Australian continent. Nonetheless, this paper provides an important framework for developing ground-motion relations in Australia for use in engineering design.
R. Herweynen, T. Griggs, E. Schrader and D, Starr
The Burnett Dam is a 50m high Roller Compacted Concrete Dam on the Burnett River, located approximately 50km inland from the town of Childers in Queensland. The design and construction of the Burnett Dam is being undertaken by the Burnett Dam Alliance (BDA) consisting of Walter, Macmahon, Hydro Tasmania, SMEC and Burnett Water. The design of the dam commenced in 2003, construction started in November 2003 and the planned completion date is mid 2005.
The Alliance Contract was awarded through a competitive process and therefore innovation was a key aspect of the design and construction methodologies. This paper will look at a number of specific aspects of the design where innovation delivered true value, namely:
The Burnett Dam design has clearly demonstrated that the unique site conditions have had a significant impact on the final design and construction methods.
The decision-making landscape has shifted markedly over the last 10 years with the implementation of COAG micro-economic reforms. These reforms have seen the separation of regulatory functions from commercial / service provision functions – yielding benefits to all stakeholders. However, the fragmented regulatory framework for dam owners (in Queensland at least) has resulted in potential conflict between price regulation and major dam safety decisions such as spillway upgrades.
This paper examines the scope for conflict in the two regulatory frameworks (pricing and dam safety) and the implications for dam owners, water users and potential new investors in the water infrastructure.
R.J. Nathan and P.E. Weinmann
Selected aspects of the guidelines dealing with the estimation of dam safety floods are being
considered for revision as part of a larger overhaul of “Australian Rainfall and Runoff”. One section
that warrants attention is the guidance provided on estimation of the Probable Maximum Flood
(PMF). The section of the current guidelines that deals with this issue received little attention in the
last revision as the focus was on estimating floods for risk-based design, that is on floods of known
annual exceedance probability. However, it is now common to jointly consider both risk-based and
standards-based components in the design process, and this has highlighted problems associated with the manner in which the PMF is defined and estimated. This paper examines the current problems involved with estimation of the PMF, and presents concepts and practical estimation approaches that could be considered for incorporation in the guidelines. The purpose of this paper is to promote discussion and elicit feedback from industry to aid the revision process.