Yarrawonga and Torrumbarry Weirs; located on the Murray River bordering Victoria and New South
Wales, are operated by Goulburn Murray Water on behalf of the Murray Darling Basin Authority.
The electrical and control systems that operate both structures were nearing 20 years of age, resulting in risk associated with equipment nearing the end of its useful working life and hardware obsolescence, driving this upgrade program. These control systems are critical in the monitoring and management of river levels and flows that extensively affect Victorian and New South Wales irrigation supplies and recreational users on the Murray River and Lake Mulwala.
Considerable effort was required to update and develop the control philosophy before proceeding to the design phase of the projects. The requirement to work on these brownfield sites, while maintaining operational ability and minimising dam safety and water delivery risks, resulted in a significant implementation and commissioning process. During the course of these works, the opportunity was also taken to enhance and update remote monitoring capability.
The lessons learnt on these projects are being incorporated into current Electrical and Control System Upgrade projects at Cairn Curran Reservoir and Dartmouth Dam.
Now showing 1-12 of 59 2982:
Kangaroo Creek Dam is a concrete face rockfill dam (CFRD) located on the Torrens River, approximately 22 km north east of Adelaide. The dam is currently undergoing a major upgrade to align it with updated safety guidelines set by the Australian National Committee on Large Dams (ANCOLD) to better withstand major flood events or earthquakes. As part of this upgrade, external omega-type waterstops have been installed on the vertical and perimetric joints to mitigate the impact of expected joint deformations due to seismic loading. Two profiles were selected for the external waterstops; one capable of extending 200 mm for the perimetric joint and the outer two vertical joints on each side, and one capable of extending 100 mm for the remaining vertical joints and the horizontal joint between the new face slab and the original face slab. Using the external omega-type waterstops as the second waterstop for the extended perimetric joint simplified construction, particularly with respect to reinforcement details adjacent to joints. It is understood that this is the first time in Australia that an omega-type waterstop is being fitted to a CFRD slab. This paper demonstrates the benefits of retrofitting waterstops to existing dam joints when required, provides general installation details, details for providing a continuous barrier with the existing waterstops by overlapping internal and external waterstops, and lessons learnt from the waterstop installation.
Millions of dollars are spent on dam upgrade works which are often undertaken to meet the flood security requirements. Prioritisation of the dam upgrade work is based on portfolio risk assessments in which dambreak modelling is an integral part. Concurrent design flow hydrographs of tributaries downstream of dam are required for the assessment of the incremental effect of a dam break scenario. The Annual Exceedance Probability (AEP) neutral concurrent tributary flows can be estimated using a bivariate-normal distribution approach.
This paper examines the underlying assumptions made in the application of the bivariate normal distribution approach using observed and design rainfall data for Avon Dam and its downstream tributary catchments. Synthetically generated data was used to illustrate the impact of the log-normal distribution assumption on the AEP neutral concurrent tributary rainfalls. This paper suggests a modification to the bivariate-normal distribution approach to estimate more unbiased AEP neutral concurrent design rainfalls. The use of historical gridded rainfall in the estimation of inter-catchment rainfall correlation is also demonstrated.
The evaluation of the maximum instantaneous uplift force produced by turbulent pressure fluctuations plays a key role in designing concrete slab protection in spillway chutes and stilling basins. Recent incidents involving damage to chute linings have highlighted the significance of this issue. To evaluate the stability of spillway stilling basin slabs, it is necessary to determine the statistical structure of the turbulent pressure fluctuations in the spillway chute and stilling basin. This can be defined by an extensive experimental work with a scale Physical Hydraulic Model (PHM). This exercise can be prohibitively expensive in terms of time and cost and it is proposed that the use of Computational Fluid Dynamics (CFD) in this application could become a cost effective alternative. A new approach using Detached Eddy Simulation (DES) was applied to the case of a scale physical hydraulic model representing a real-world prototype and the results of the simulation were compared with the direct laboratory measurements. Here the forces and pressures acting on the slabs are evaluated using both CFD and physical hydraulic modelling results. In conclusion, some considerations on the design of slabs with unsealed joints are reported and discussed.
Physical modelling of dam structures remains a preferred method for validating and improving dam designs. Flow behaviour in the approach and over the crest of a dam can be accurately studied with traditional methods such as pressure transducers, piezometers and current meters due to the relatively smooth and steady flow conditions. However, characterising flows within a stilling basin is far more difficult due to the complex, aerated and highly turbulent flow conditions. Recent work on detailed measurement of hydraulic jumps using a line-scanning Lidar was adapted for measurement of stilling basin surface profiles in a 1:50 scale model of Somerset Dam, QLD. Lidar was shown to be an effective and efficient tool for providing assessment of the toe jump, boil and flow into the downstream channel.
There are a number of software packages that have been developed to conduct Probabilistic Seismic Hazard Assessments (PSHA’s). Each one has advantages and disadvantages. Two such programs are compared; the licenced subscription-based EZ-FRISK software package developed by Fugro USA Land, Inc. and the open-sourced OpenQuake-engine (OQ) software package by the Global Earthquake Model (GEM) Foundation. Both of these packages use the classical PSHA methodology as described by Cornell (1968) and modified by McGuire (1976). Each of these packages offers different advantages; OQ is freely distributed, code based and provides easy access to a number of tools. EZ-FRISK doesn’t rely on command-line tools and instead provides an easy user interface with quick access to plots to check results. EZ-FRISK is computationally faster than the OQ program.
A simple rectangular source model with four sites was used to investigate the degree of agreement between these two software packages. Results indicate that hazard estimates from the two packages agree to within 4% for the two closest sites. At long return periods for the two furthest sites, the difference is larger.