The Snowy Mountains hydroelectric scheme now faces environmental opposition on a daily basis. While historically hydro-dependent Tasmania is set to import thermal power from the mainland. Is this the future for the Australian water power and dam construction industry? Phil Cummins reports
The 50-year-old Snowy Mountains hydroelectric scheme did much to develop Australia in the post-war period. Thirty years on since completion of the final phase, the project’s immigrant workforce has become part of a multi-cultural nation. But such events are unlikely to be repeated in Australia, where there is limited activity in relation to major hydro schemes. Few sites remain where an economic, environmentally friendly and politically acceptable major hydro facility can be constructed.
Once viewed as a national icon, the environmental effects of the Snowy Mountains project are now being questioned on a daily basis, at increasing volume. Decisions on the diversion of water, which made sense at a time of rapid national development, are now seen as questionable. The value of the riverine environment in the Snowy river is seen to be as important as the hydro power and irrigation water that was obtained by diverting part of the river flow inland.
The tensions over dam construction and the environmental value of our rivers can be traced back to Tasmania.The state, which had relied on hydroelectricity for most of its power, has not constructed additional capacity for a decade. The Gordon below Franklin scheme, and the protests that eventually led to its abandonment, did much to promote environmental and planning laws in Australia; as well as to harden the views of environmentalists against major hydro power schemes. Bass Link, an undersea cable connecting Tasmania with the mainland, is about to be constructed to facilitate the exchange of base load power from Victoria’s coal-fired stations for Tasmania’s peak load capability.
The pressure to reduce greenhouse gas emissions has led electricity reticulation companies to offer their consumers green electricity from renewable energy sources at a premium price. Such a strategy, which has been well accepted by the public, has led to the development of wind farms, solar arrays and biogas generating facilities. New hydro and efficiency improvements are eligible to be considered as being green and a large number of small generating stations have been installed on the outlets of dams and weirs, and as pressure reducing devices in reticulation systems; while older facilities are being upgraded and operated in more efficient ways.
The majority of Australia’s large dams have been constructed principally for the purpose of water storage for irrigation and industrial and domestic consumption. Irrigation is, of course, the largest consumer and has driven dam construction in virtually all states.
Australia’s major river system, the Murray Darling Basin is so heavily committed that in most years no water actually flows to the sea. Any additional demand for water has to be met either by purchasing the water from an existing user or by increasing distribution efficiency. This is encouraging the development of high value irrigated crops and is a factor in Australia’s large increase in grape production.
Opportunities for further regulation of rivers are limited outside of Queensland and Western Australia, and even in these two states we are unlikely to see the development of new large scale irrigation areas.
Australia has a stock of old dams. The development of rural towns in some of the country’s driest areas led to large numbers of relative small dams being constructed. A significant number of the water supply dams were built in the nineteenth century and some built prior to 1860 are still in service. These consist of a variety of types of dams including gravity, arch and earthfill structures.
Initially it was believed that the major reason for dam rehabilitation works would be spillway inadequacy. Australia had developed generalised methods for estimating probable maximum precipitation, coupled with improved methods of calculating predicted run-off from extreme rainfall events. While these methods led to the recognition that the majority of older dams required some upgrading to pass extreme rainfall events, the development of risk assessment techniques for dams showed that in many cases the risks of internal erosion arising from cracking, displacement or earthquakes posed a greater risk.
Extensive rehabilitation works have been completed on about 15% of the total stock of dams, with at least a similar number to be rehabilitated over the next decade.
ANCOLD and WCD
The Australian National Committee on Large Dams (ANCOLD) has welcomed the World Commission on Dams’ (WCD’s) report. While ANCOLD has been at the forefront of the development of environmental policies and practices for dams, it recognises that the WCD report will pose challenges for many nations, particularly in developing countries. Never-theless, ANCOLD actively supports the concept of understanding and accounting for the full cost of dam development.
Without large dams it would be difficult to provide domestic water for Australia’s population, even if we ignore the large proportion of our food production that comes from irrigated agriculture. With our low and unreliable rainfall, dams are essential. It was disappointing that WCD did not seek to present a balanced view of such advantages of dams.
Equally ANCOLD has concerns about some of the decision-making processes recommended by the Commission. In many countries, planning legislation already imposes processes similar to the WCD process. The form of government chosen by people does vary. Some governments encourage the participative decision-making recommended by WCD but in other countries the people have chosen different processes as they feel these better suit their needs. We must not impose a single model on everyone.
ANCOLD has an active technical committee and produces guidelines to assist its members in conforming with best practice in all elements of dam management. Its most recent guideline was on the environmental management of dams. Its aim was to ensure that those involved in the design, construction, operation and maintenance of dams are well acquainted with the relevant legislation and environmental objectives of government. While this reflects current Australian legislation and icold bulletins, it sets out to encourage the highest possible environmental and social standards in dam design, construction, operation, management and rehabilitation.
ANCOLD will strive meet the challenges set by WCD by:
• Joining with other appropriate organisations to develop a guideline on project evaluation, which encompasses all phases with an emphasis on continuous learning.
• Revising our organisational structure and arrangements to make it more attractive to the full range of people working in the field of water storage, conservation and usage with an emphasis on river management. The structure must encourage collective working with appropriate groups.
• Ensuring that we include community groups in our decision-making and review processes, including eval-uation processes.
• Set up a dams accreditation process to allow accreditation of dam management and evaluation processes.
ANCOLD has already set up a committee to examine ways of extending its existing dam database. It is currently working with emergency management organisations to develop model emergency management arrangements for dams and to ensure that communities are fully informed and involved.
The ANCOLD executive is also reviewing all aspects of its rules. It hopes to make the organisation more attractive to those who understand the environmental and social consequences of dams, reservoirs and the river system; particularly those who wish to make Australia’s water regulation as effective as possible.
The committee will also address the need to work on guidelines for the responsible decommissioning of dams. We look forward to working within the framework that WCD has produced to ensure that each dam meets community expectations in terms of technical standards, environmental effects, social consequences and water efficiency. This will depend on developing dialogue with each group in the community.