Brian Haisman, Clarke Ballard and Neville Garland
In early 1997 the Murray-Darling Basin Ministerial Council instigated a review of the operations of its primary reservoirs, the Hume and Dartmouth Dams, in response to concerns of floodplain communities below the dams, coupled with changing community values in relation to the in-stream environmental effects of dams. The review, completed in May 1999, achieved a consensus between parties advocating what are on the surface irreconcilable objectives for the management of the water resource. Foremost competing objectives were flood mitigation, consumptive water use, and environmental health of the river system, plus subsidiary objectives related to recreation, hydro-electric generation, salinity management, tourism and the like. The keys to success were firstly, creation of a community-based Reference Panel which took on a steering role coupled with extensive consultation, and secondly a determination to describe situations wherever possible by means of factual information. The paper describes the identification and evaluation of issues, the consensus building process, the intensive hydrology and economic modelling undertaken, and the development of a comprehensive set of flow parameters which could be viewed as surrogates for environmental outcomes. Conclusions and recommendations are drawn for future reviews of similar dams.
Michael Cawood, Roger Jones and Ken Durham
A methodology for local disaster management planning based on Australian/New Zealand Standard AS/NZS 4360:1995 — Risk Management has been developed as an out-working of a Flood Risk Study for Murweh Shire. The methodology has relevance to all local governments, particularly in view of National Disaster Relief Arrangements (NDRA) that now link the extent of NDRA funding available for a re-occurring natural disaster event to the existence of disaster mitigation actions or plans. This places a premium on actions being taken by local governments to mitigate public safety risk at community level.
A strategy designed to ensure that an existing dam continues to perform effectively will include:
This paper will explore each of these issues and how they may be applied to dams in a variety of situations. These situations include water supply reservoirs, flood retarding basins, levees and wastewater lagoons. While each situation is different, the underlying principles will remain consistent. The range of situations encountered by Victorian Water Authorities provides the inspiration for the development of an efficient approach to the management of the safety of dams.
The Bundaberg Irrigation Area (BIA) is served by a reticulation system of channels, pipelines, pump stations and balancing storages drawing water from a major dam (Fred Haigh on the Kolan River), augmented by a number of weirs and tidal barrages. The scheme as originally proposed in the late 1960’s included a major dam on the Burnett River that has never been built. Accordingly, the reliability of the system was lower than desired, a situation exacerbated by prolonged drought during the 1990’s.
In the 1980s, alternative (cheaper) sources of water supply were investigated and a weir site on the Burnett River (Walla) was selected as the most promising. In 1993, the Commonwealth and Queensland Governments agreed to the Sugar Industry Infrastructure Package (SHP). Walla Weir was included in the Package, subject to environmental and economic assessment.
Detailed impact assessment studies were carried out and submitted to both State and Commonwealth Environment departments. In the light of strong opposition from environmental groups (whose major concern was the Queensland Lungfish), the Federal Minister for the Environment commissioned an independent review of the IAS before granting approval.
Approval was conditional on the implementation of an Environmental Management Plan and a River Operation Plan as well as a commitment to undertake extensive baseline studies before any new development is proposed in the area. This paper will discuss the investigation and approval process and describe the additional monitoring/studies being carried out.
Shane McGrath and Michelle Cowan
Goulburn-Murray Water (G-MW) is a Victorian rural water authority with responsibility for management of the major water systems within a 68,000 square kilometre region. Following a detailed business risk assessment undertaken in 1996, Goulburn-Murray Water developed a ten-year program to commence design reviews and address identified deficiencies at thirteen dams for which G-MW has responsibility.
In October 1997, the Victorian Government announced a $450 million regional water reform package, of which $35 million was provided for rural water authorities dam improvements. $18.5 million was allocated to G-MW on a ‘dollar for dollar’ basis. With contributions from G-MW customers, the current total funding amounts to $37 million.
This paper focuses on processes that G-MW has adopted to manage an accelerated program of dam design review and remedial work.