The Aquifier

The Burdekin Delta is an ‘Open Aquifer". Groundwater of good quality is contained against the sea with constant leakage to that environment. The Delta Aquifer is subject to six processes which affect the water level:
  • Rainfall recharge
  • Irrigation Withdrawal
  • River recharge
  • Flood recharge
  • Artificial recharge
  • Leakage to the ocean.

Rainfall is an uncontrolled event which provides natural benefit directly to crops and then percolates through the soil to the aquifer.

Groundwater extracted from the aquifer is used for crops as well as domestic water supply. Private bores lift water to the surface and on farm. Local Authority (Council) bores provide town water and industrial supply through reticulated infrastructure.

River pumping is a Board activity to lift water from the Burdekin River for distribution throughout the defined area. Surface water is directed into ‘recharge areas' or supplied to Farmers which compliments replenishment by ‘water spreading'.

Recycling irrigation tail water on farm is a limited practice due to the nature of delta soils and leakage of retention ponds to the aquifer.

Permeability of delta soils assists in the retention of irrigation excess, providing cheap drainage to the aquifer of water not taken up by the crop or transpiration process.

Groundwater moves freely through streams in porous areas of the aquifer, however texture of sedimentary deposits do vary considerably from pure coarse sand with large stones to heavy clay.

The delta area within tidal limits is a good example of progression of the flood plain where heavy clay mud islands carry vegetation and the creeks in between are gradually silting up with outflow of mostly porous sandy material. The SBWB has areas alike to old mangrove islands below top soil which generally have poor quality groundwater and almost no bore field potential.

Groundwater quality overall is generally good and is suitable for irrigation of sugar cane and most domestic purposes. Zones of differing quality exist and are the result of either leakage of higher salinity groundwater from adjacent bedrock on the southern boundaries or from old seawater contained within the sediments as part of a ‘natural saltwater wedge'.