‘I love a sunburnt country…a land of sweeping plains… of ragged mountain ranges… of droughts and flooding rains’ is a familiar refrain to many of us.
South East Queensland has a climate of extremes – from storms and floods, to heatwaves and droughts.
The reality is that another drought will happen in South East Queensland.
While we are one region, dry conditions may persist in a part of our region – such as right now, in the Lockyer Valley, while others enjoy healthy dam levels – such as the Gold Coast.
We may need to tailor our operational response to particular sub-regions, given the combinations of water sources they have and the ability of the SEQ Water Grid to move water to that sub-region.
CASE STUDY: SUNSHINE COAST
Our focus was drawn to the northern sub-region in 2017 after it experienced a second failed wet season in 2016-17, which was unusual. The two main major storages in the northern sub-region are Baroon Pocket Dam and North Pine Dam. From 2015, Baroon Pocket Dam and North Pine Dam were progressively drawn down as rainfall was insufficient to fully replenish them. The northern sub-region also relies on Ewen Maddock, Cooloolabin, Wappa and Lake Macdonald dams.
- Baroon Pocket Dam is a relatively small storage with a volume of 61,000ML (equivalent to only 5% of the Wivenhoe Dam storage volume). The catchment that contributes flows to Baroon Pocket Dam has been a reliable source, historically using about 60% of its capacity each year.
- The size and nature of Baroon Pocket Dam means that extended drought conditions can result in a decline of water levels and very limited time to implement contingency measures.
- North Pine Dam has a larger storage with a volume of 214,000ML compared to Baroon Pocket Dam (equivalent to 18% of the Wivenhoe Dam storage volume).
A key consideration for water supply in the northern sub-region is the time required to implement contingency measures in the event of extended drought conditions.
The southern sub-region can access the Gold Coast Desalination Plant, while the central sub-region can use the Western Corridor Recycled Water Scheme.
The recent dry period has highlighted the vulnerability of the water storages in the northern sub-region to drought without appropriate water transfers from the central to the northern sub-region via the SEQ Water Grid. In 2017, the grid was used to transfer water to the Northern sub-region, supplementing the sub-regions local water supply. Seqwater continues to operate the grid in this manner. While the grid is able to provide water to this sub-region, its capacity is limited and cannot meet total demands without input from local water supplies.
The Sunshine Coast case study is an example of why we must plan for every possible scenario to ensure we have enough water to meet the needs of all of South East Queensland communities