A PILOT project in the Burdekin is showing promising early signs indicating that dewatering bores could become an effective weapon in helping combat rising groundwater levels.
Funded via the Rural Water Use Efficiency – Irrigation Futures scheme, five dewatering bores have been drilled on farms connected to the Burdekin-Haughton Water Supply Scheme.
Maintaining soil moisture has kept farmers on their toes during one of the drier growing seasons in the Burdekin.
Bureau of Meteorology data from the nearby Clare weather alert showed just 360mm of rain dropping into the gauge for the four months to the end of April.
May was bone dry meaning Mother Nature’s contribution to the sugarcane growing effort in 2015 about 60 per cent of average.
“We’re fully irrigated and rely on the irrigation, if we didn’t irrigate we wouldn’t have cane,” Burdekin Productivity Services extension officer Marian Davis pointed out during an inspection of a dewatering bore on Mark Hatch’s farm.
“But we need to really manage that irrigation so we don’t have bigger problems being created by doing exactly what we need to do to grow our cane. Irrigation management to reduce deep drainage is really important in the Burdekin to keep those ground water levels as low as possible.”
Since the earliest years of farming in the Burdekin delta, cane growers have depended on water from the aquifer to nourish their crops. As the most productive growing region has expanded, substantial irrigation infrastructure has been constructed to supply an increasing demand for irrigation water to the farmlands of the Burdekin-Haughton water supply scheme.
High in the catchment, the system is fed by the state’s largest water storage, the Burdekin Falls Dam. Water is released downstream to the Clare Weir, where pumping stations supply irrigation channels and also recharge groundwater supplies in the Burdekin Delta.
Human intervention, according to Marian Davis, has altered the hydrology of the lower Burdekin in such a way that the aquifer is being replenished at a much faster rate than it can drain.
“We’re adding water constantly through irrigation, through channels, the river runs all the time now so there’s a water head in the river and we’ve just changed the hydrology and environment around us and if we keep adding water to the system we’re bound to start increasing the ground water levels as it drains,” Marian said.
“In this area we’ve noticed, since the irrigation area was opened up in the early 90s, there’s been quite a rapid increase in the level of underground water. It would have started around 12 metres and now it’s up to around six metres in places or much higher, so it’s starting to be a real concern.”