Flow

A look at the flow required in key locations

Based on the flow event from early 2023, it seems that attempting to navigate this river will be difficult.

Due to the remoteness of the system and limited water gauges, I found it more difficult to analyse the flow down the waterway compared to other rivers. To assist with the task at hand, I used Sentinel Hub to track the flow down using satellite imagery. I found that customising the imagery by using bands 12, 11, and 2 for the red, green, and blue channels made this task much easier. This creates a bright yellow image with a dark ribbon for the water in the channel, making it easy to visualise the flow as it slowly makes its way down.

While there was some rain in the headwaters, it only provided a short one-day window of opportunity to attempt the Augathella to Charleville leg. The majority of the flow came from Ward River (30 GL), taking 6.5 days to flow the 220 km to Cunnamulla at approximately 34 km/day. This provided a good four day release of a 4,000 ML/day flow at Cunnamulla Weir. From there, it took 15 days to reach Fords Bridge at just 20 km/day, and the flow was reduced down to around the 200 ML/day mark. It became obvious that much of the flow was lost to Cuttaburra Creek.

After doing some more research, some key observations include:

• The Nive, Langlo and Ward rivers are important tributaries in the upper basin often feeding more water into the system than the upper Warrego headwaters.
• The flow seems to correlate to localised rainfall runoffs, albeit the entire upper basin tributaries have converged by the time you get to Cunnamulla.
• A decent flow at Cunnamulla is needed before the waters will reach the lower reaches and into the Darling.
• Large floodplains and Cuttaburra Creek buffer and reduce the flow reaching the lower Warrego. More flow can be observed leaving the system from Cuttaburra Creek towards Yantabulla Swamp and the Paroo than flowing downstream on the Warrego past Barringun.
• A large number of dams seen in the lower section slows the flow down significantly and could hinder it from reaching the Darling completely.
• If the billabongs / pools are anything like those in other areas around the Darling Downs, the smaller ones will quickly dry up making traversing a non-flowing stream extremely difficult.
• Flow longevity is short, limited to a week or two unless there is persistent rainfall.