Dr Azan Khan, Ahmad Nasir, Kumud Kandel, Jaya Kandasamy, Hadi Khabbaz, Mahub Ilahee
Cracking in the clay core of embankment dams is important to dam safety because it can cause seepage through transverse cracks and with excessive seepage cracks may begin to erode the soil on the sides of the crack. If there are no filters to control this erosion, the erosion may progress to form a pipe, eventually leading to breach of the dam. Recent climate change has resulted in long term drought conditions in various parts of Australia, especially west of the Dividing Range. The prolonged drought conditions can lead to the loss of moisture content in the clay core causing cracking of the core material. The current research is investigating a relationship between long term drought condition and loss of moisture content in the clay core. This paper presents the loss of moisture content in the clay core of three dams in Australia due to global warming. A rigorous finite element modelling has been conducted to capture the moisture content changes in a typical large clay core dam.
Keywords: clay core, dams, climate change, moisture content
Alice Lecocq, Bob Wark, Paul Hurst, Michael Somerford
The justification for dam safety remedial works is often based on an assessment of life safety risk and financial losses defined at a discrete point in time. However these parameters are likely to change over time with demographic growth, land and industrial development. The Water Corporation has a number of dams upstream of major growth areas and an understanding of the future direct and indirect economic consequences of dam failure are required in order to define the change in risk profile over time.
This paper outlines the study framework adopted by the Water Corporation to review its capital expenditure on its remedial works programme. Dam failure consequence assessments for Wellington, Serpentine and Samson Brook Dams are presented and the paper describes the methodology adopted to forecast the likely development within the inundation areas. A framework to consistently estimate future changes to life safety and economic consequences is also presented.
Keywords: demographic growth, land and industry development, monetary assessment, future trends, consequence assessment.
John Prentice, Jim Barrett, Dr Martin Mallen-Cooper
Located in south-eastern Australia, the River Murray has provided almost a century of regulated water supply, bringing immense benefit to human welfare during this period. However a healthy river is recognised as being essential to its sustainable future. With this in mind, in March 2001 the Murray- Darling Basin Ministerial Council approved several actions including “a structural works program to provide passage for migratory fish, from the sea to Hume Dam”. The paper outlines progress to-date on this ambitious fishway construction program.
The program involves building fishways on twelve of the fourteen weirs on the river, and at the barrages. The criteria established, to enable passage for all native fish species known to regularly migrate, are detailed. The important lessons learned from earlier fishways, and confidence gained from the Torrumbarry Weir vertical-slot fishways constructed in the 1990’s, have been applied to the new designs. Part way through the program, important changes were made to the design criteria, and the reasons for doing so are described.The fishways constructed at the barrages near the Murray mouth, and their need to respond to estuarine and lake conditions, are recognised. In addition, Mildura and Euston Weirs vary from the other River Murray structures, and their special fish passage consideration is described.
In achieving a successful outcome to date, the important role of river managers, engineers and scientists working together with design consultants is acknowledged. A tri-State monitoring and assessment program has been established to enable the questions about the short and long term outcomes of the program to be answered. The beneficial results to date are detailed.
This paper outlines the steps and challenges involved in delivering this decade long program, scheduled for completion in 2011.
Keywords: Sustainable, fishways, fish passage, native fish, hydraulics, fish monitoring, Murray.
In 2003, the Bureau of Meteorology revised the Probable Maximum Precipitation estimates and rainfall temporal patterns for Tinaroo Falls Dam using the Revised Generalised Tropical Storm Method. Based on the revised floods, the dam was assessed as having an ‘Extreme’ Flood Hazard Category rating. Subsequently a comprehensive risk assessment was undertaken in 2008 and this assessment recommended the dam be upgraded to pass the Fallback AFC which is the PMF event. The current spillway has a capacity for a flood with an AEP of 1 in 200. To achieve the AFC the concrete gravity Main Dam requires stabilising with post-tensioned anchors. The crest of the homogenous Saddle Dam needs to be raised by 300 mm and a filter and weighting zone needs to placed on the downstream face
Keywords: Tinaroo Falls Dam, mass concrete gravity dam, post-stressed anchors, Barron River, filter, weighting zone
David Ryan, Simone Gillespie
The Burdekin Falls Dam is the largest of the 19 dams owned by SunWater. The dam is located on the Burdekin River at AMTD 159.3km, approximately 210 km south of Townsville and supplies water for irrigation, urban and industrial development in the lower Burdekin Region. The dam has such unique features as the largest spillway of any dam in Australia and a catchment area of 114,770 km2, which is equivalent to about 1.7 times the land area of Tasmania. It is proposed to raise the dam to provide a more certain water supply for the North Queensland region. This paper outlines the features of the existing structure, the influence of the revised hydrology since the time of its construction and the options considered in the planning and design of the raised structure.
Keywords: Burdekin Falls Dam, unique features, spillway, fuse plug.
Tommie Conway, Katherine Miller, Peter Hill
The ‘Black Saturday’ fires of the 7th of February 2009 and the continuation of fires over the following weeks had devastating human, environmental and financial costs for Victoria. Many of Melbourne’s water supply catchments and assets were burnt and the major harvesting catchments were seriously threatened. This paper highlights the need for owners and managers of catchments, dams and associated infrastructure to better understand and plan for the potential impacts of fire, given its predicted increased likelihood and severity due to climate change.
The paper will share Melbourne Water’s recent experiences of the fire, the scale of the impact to the business in terms of assets damaged and catchments affected, the extent of the burn and the threat that was faced. It will describe Melbourne Water’s experience with the United States Burnt Area Emergency Response (BAER) team to expediently map the severity of the fires, to identify areas of concern and prioritise fire recovery works. Of interest to those involved in risk management will be the discussion of the construction flood risk analysis at Tarago Reservoir which was revisited due to severe fire damage to the catchment.
Keywords: fire impact, Melbourne’s water catchments, BAER team, hydrology, Tarago, construction flood risk analysis