Floodplain Manager November 2019


I have recently read some books about key military campaigns during the First and Second World Wars and a recurrent theme is how often detailed battle strategies become unworkable soon after the battle begins because things don’t turn out as expected.  Time again field commanders are faced with a decision whether to follow orders based on HQ theory or to improvise in the face of reality.  There were those who followed orders and sent thousands to their deaths but were not criticised for doing so as they were doing exactly as they were meant to do. There were those who improvised, saved lives, won strategic ground and even won battles and were commended for their initiative and bravery.  And then there were those who took the initiative, things did not go well and they were court martialed for disobeying orders.  He who dares does not always win because human decision making in battle is based on expected actions by the enemy and outcomes which are not certain.

The same can be said about emergency management, including flood emergency management.  Scenarios need to be considered and response plans need to be prepared in advance but situational awareness and improvisation also have their place.  The challenge remains, however, for those responsible to know when to deviate from the plans, if at all.  Last week, the NSW Supreme Court judged that in the case of the operators of Somerset and Wivenhoe dams in January 2011, the operators should have followed the detailed operating plans for the dams irrespective of how they themselves were interpreting the unfolding weather events.  I have not had the opportunity to go through the judgement in detail, let alone the 26,000 documents which underpinned it, but the message from the Court is clear: follow the operating rules to the letter or be found liable.

The challenge with preparing operating rules for flood mitigation dams is that no matter how you operate a dam you don’t stop the flooding, you just change where and when the flooding occurs. It is a trade off not only between upstream and downstream impacts but also between one set of downstream impacts and another set of downstream impacts because the floodwaters have to eventually flow downstream.

After the Brisbane dams were built, there was a perception in the community that they had removed the flooding problem for Brisbane, and downstream development and community preparedness reflected that perception.

We see this month that the NSW SES is being criticised for running a community education campaign in the Hawkesbury Nepean Valley, which has arguably the high flood risks in Australia.  The detractors say that this is a back door marketing campaign for raising Warragamba Dam to provide a flood mitigation function.  The reality is that whether flood mitigation is provided at Warragamba or not, those living in the Valley will still face significant flood risks, and urban planning and community preparedness need to be responsive to it.  The NSW SES must take steps to improve community preparedness in the Valley and state and local government must enforce appropriate planning controls.

The challenge will be to maintain the preparedness and the controls after the current investment in the Hawkesbury Nepean Valley Resilience Strategy has been completed, otherwise gains made now may be eroded over time.  Furthermore, as several international research pieces show this month, reliance on engineered mitigation structures and top down approaches to flood warning and preparedness may provide sub-optimal mitigation benefits with communities thinking the “flood problem” has been eliminated or is someone else’s responsibility.

Steven Molino

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