SEQWater is the major supplier of bulk water to Local Governments and industry in South East Queensland. SEQWater owns Wivenhoe, Somerset and North Pine Dams. Wivenhoe Dam ( Lake Wivenhoe) is located on the Brisbane River in Esk Shire. The storage provides both flood mitigation and water supply storage to Brisbane and Ipswich. The water supply storage capacity at full supply level is 1,160 GL. An additional 1,450 GL of storage above full supply level is used for flood mitigation.
Changes to the estimation of extreme rainfall events has resulted in significant increases in the estimates of the PMF since the original design of Wivenhoe Dam. To upgrade the dam SEQWater formed an alliance with Leighton, Coffey, MWH and the NSW Department of Commerce Dam & Civil Section.
A preferred upgrade option for Wivenhoe Dam has been selected, designed and construction started by the Wivenhoe Alliance. This paper presents details of the selected upgrade option.
Now showing 1-12 of 59 2968:
Maged Aboelata, David S. Bowles, and Anthony Chen
This paper describes and demonstrates some recent enhancements in LIFESim, a modular, spatially distributed, dynamic simulation system for estimating potential life loss from natural and dam-failure
floods. LIFESim can be used for dam safety risk assessment and to explore options for improving the effectiveness of emergency planning and response by dam owners and local authorities. Development of LIFESim has been sponsored by the U.S. Army Corps of Engineers and ANCOLD.
Recent enhancements include a dynamic transportation model in the Warning and Evacuation module, additional variables in the Uncertainty Mode, and some new output displays. The transportation model represents the effects of traffic density on vehicle speed and also contraflow, which is sometimes used in evacuations, without requiring the details of road geometry and traffic signal operations.
The Deterministic and Uncertainty Modes of LIFESim are demonstrated for the sunny day failure of a
large dam. Sensitivity studies are presented for varying the warning initiation time, four emergency
shelter location cases, and a five-fold increase in population with no change in the capacity of the
road network. Comparisons with the Graham  Method are included. Plans for further model
development are summarised, including a user-friendly version that can be distributed to other users
and a Simplified Mode for making approximated life-loss estimates for preliminary studies.
The Eildon Alliance is currently undertaking the upgrade of Eildon Dam as part of Goulburn Murray Water’s dam improvement program. The Alliance is responsible for all aspects of the project, including planning, approvals, detailed design and documentation, construction and commissioning. The dam is an 80 m high zoned earth and rock fill embankment with a concrete lined spillway excavated through the left abutment. The spillway control structure is a 33 m high mass concrete dam, with a 60 m wide gated overflow section. The spillway chute is a 435 m long, 60 m wide concrete lined channel through steeply dipping fresh to highly weathered rock. The dam and spillway were originally designed to pass a peak discharge of 3 400 m3/sec however recent hydrology indicates the current PMF discharge will be 6 900 m3/sec.
Work on the spillway upgrade included a physical model study that identified very poor flow conditions resulting in very large transient pressures. It was concluded that the existing concrete lined discharge channel will likely fail in relatively frequent flood events, with the potential for extensive erosion of the chute foundation. In a major flood event it is possible that the failure of the chute could ultimately lead to undercutting of the spillway structure.
This paper discusses the design approach selected to secure the spillway structure including lifting of the concrete slabs, erosive potential of the underlying rock strata and erosion mechanisms of down cutting and back cutting once the chute has failed. The paper also includes a discussion of the international work in this field used to quantify the measures required to protect the spillway structure at Eildon Dam.
Ross River Dam is dam of extreme hazard located immediately upstream of a population in excess of 100,000. A comprehensive review undertaken by a team of international experts (ref 1) identified a number of unacceptable risks that required immediate attention.
The State Government designed and oversaw the construction of the dam that was completed in 1976. NQ Water is of the belief that the problems identified by the team of international experts were a result of poor design by the State and inadequate attention by them during the construction process.
NQ Water developed a comprehensive communications plan (ref 2) with the objective of keeping the community adequately informed, gaining positive media exposure, obtaining the support and confidence of the business community and key stakeholders, and securing State Government funding towards the upgrades.
The climate at the time was characterised by adverse media history in relation to the dam, reluctance by the State Government to take responsibility, and poor brand awareness of NQ Water and its activities.
This paper focuses on the process undertaken by NQ Water in engaging the community, various levels of Government, key stakeholders, and business community, which resulted in securing the necessary funding for the dam upgrades. It will discuss the key elements and components of the communications plan, their objectives, the results achieved, and lessons learnt.
The Murray Darling Basin Commission through its native fish strategy has embarked on a comprehensive program for improving fish health in the basin. The strategy is aimed at managing and mitigating a range of threats including loss of habitat, altered flow regimes and thermal pollution downstream of large dams.
To help identify the relative benefits of different management options SKM developed a numerical ecological model. The model produces an index score that provides a measure of condition for native fish under various habitat, flow and temperature scenarios. The model uses a series of preference curves that define habitat requirements, critical spawning periods, spawning temperature thresholds and upper and lower temperature limits for egg, larval and adult survival. An index score of 1 is applied if conditions are ideal and an index score of 0 is applied if conditions are intolerable. Different temperature time series and habitat extent can be modelled to generate condition scores related to each fish life-history stage. Comparisons between the natural condition and those related to various reservoir release regimes can be made, for example to examine the likely effects of cold water releases or the benefits that could be achieved through the use of multi-level outlets. This can be compared with the relative benefits of restoring habitat or changing flow regime.
The results from a case study examining the relative benefits to native fish from managing flow, temperature and habitat downstream of Dartmouth Dam will be presented.
Ian Hampton, Dr Mohand Amghar and James Willey
The Eildon Dam Improvement Project is being undertaken by Goulburn-Murray Water as part of its dam improvement program that includes an upgrade of the existing Lake Eildon spillway that passes through the left abutment of the dam. The main components of the spillway are a gated concrete gravity overflow section that is 33 m high and 60 m wide, a 435 m long low gradient spillway chute and a hydraulic jump stilling basin.
The spillway was originally designed, including a physical model, in the 1950s to pass a maximum discharge of 3,400 m3/s with a maximum reservoir head of 9.0 m above the spillway crest. This can be compared with the 2003 flood hydrology and flood routing studies that result in a PMF discharge of 6,900 m3/s and a maximum reservoir head of 14.1 m above the spillway crest.
A new physical hydraulic model study was carried out over 2003-2004 as part of the investigations by the Eildon Alliance for the Project. The model was tested with discharges up to and exceeding the upgraded PMF. Very turbulent conditions were observed at discharges exceeding the original design discharge including the formation, build-up and collapse of large diameter vortices in flow over the spillway crest and overflow section. The vortex phenomena resulted in the intermittent formation of high waves and very high transient pressure loadings at the downstream toe of the overflow section and extending to the upstream section of the spillway chute. The paper discusses some scaling issues, presents some of the salient results of the study and discusses their application to the 2003-2004 design of structural modifications for the spillway.
The paper includes a discussion and comparison of the 1950’s model study with the 2003-2004 study. The magnitude of the vortex phenomena could not be predicted from the previous studies, and it is recommended that investigations for upgrades of similar works that involve large increases in design discharges include detail examination of vortex phenomena.