The potential for serious consequences when dam assets are affected by unforeseen conditions was on display during the Queensland floods of 2010 and 2011 and the consequential problems with the Wivenhoe Dam, releases from which were blamed for massive flooding in Brisbane and were necessary in order to prevent the dam wall from collapsing.
Of course, this was not the first time in which dams have been associated with significant levels of disaster. In one particularly tragic case, around 171,000 people were killed in China after the collapse of the Banqiao dam amid extreme rainfall beyond planned design capacity brought on by Typhoon Nina.
In Australia, the Australian National Committee on Large Dams (ANCOLD) Incorporated lists 564 large dams spread throughout the country. Whilst safety standards are generally considered to be high, the events of Wivenhoe demonstrate that we are not immune to risk, albeit with the nature and level of that risk obviously varying according to regions and climate zones.
Accordingly, it is important to think about how we are doing with regard to risk management in this area and whether or not there are any areas in which we could improve.
Sunwater Flood and Streamflow Manager James Stuart says dam operators in Australia generally adopt a proactive approach in respect of the rigor with which preventative monitoring, maintenance and management is undertaken and there is a growing appreciation with regard to the importance of emergency management plans. The latter point has been particularly important, he says, as conversations undertaken as part of the process of preparing plans have created opportunities for significant areas of learning.
It is also important, Stuart says to move away from a mentality revolving around frequency of events – which at any rate is often difficult to estimate with confidence. He says the crucial thing is to plan for and be prepared for what could potentially happen along with the possible consequence, and that talk about events being infrequent risks breeding complacency.
“If you tell somebody that a certain level is a one in 10,000 year flood, it’s very difficult to then convince them to prepare because it might happen,” Stuart said. “Their own assessment of that risk is that it will never happen in their lifetime.
“[However,] If that probability is actually wide of the mark by an extensive margin, there is some possibility that it will happen within their lifetime.”
As part of continuous improvement, Stuart says Australia could lift its game further in terms of planning for high risk events as they pertain to dams and ensure we are better prepared for those ‘what if’ type of catastrophic events which might have a relatively low frequency of occurrence but which we nonetheless need to be ready for. He says Australia does not have a great deal of experience in this area as we have not, apart from a 1929 collapse, experienced major catastrophies when it comes to dams.
Beyond that, Stuart says it is important to have a clear communication strategy in place which delivered a single ‘point of truth’ in terms of information when a disaster does happen, and to use technology which goes beyond warnings systems based around districts, areas or single point of locations populated areas to those which provide specific information to individual property owners with regard to specific risks to their individual property.
Malcolm Baker, principal engineer of dams at international water and civil engineering services provider GHD says Australia is well regarded internationally in terms of its approach to building and operating water based infrastructure, with large dam owners generally adopting a proactive approach toward management of risk and practices within each state being well informed by ANCOLD guidelines. He noted, however, that there is further opportunity for improvement in terms of communication to the general public regarding the operation and maintenance of dams as well as potential risks which they impose.
By what he says is a comprehensive approach to risk management, Baker says the water industry serves as an example for owners and operators of other types of infrastructure to follow. He says an interesting complexity with regard to risks associated with dams as opposed to those who choose to use road, rail or airport related infrastructure revolves around the ‘voluntary’ nature of the risks undertaken by those who elect to use these other pieces of infrastructure as opposed to the ‘involuntary’ risks forced upon those exposed to potential dam failure.
Given the infrequent nature of catastrophic events which impact dam infrastructure, finally, Stuart says it is important to look for lessons learned overseas, such as those learned with regard to simplicity of communication strategy during the Sacramento Dam disaster in Brazil. In that case, with a lot of mobiles being washed away, having somebody shout that people needed to run proved to be the most effective tool available, he says.
Australia generally has good practices with regard to dam risk management.
Should we adopt a few further strategies, our performance in this area could yet improve further.