Objectives
The North and South Burdekin Water Boards, now Lower Burdekin Water (LBW), were formed in the mid 1960’s to acquire land, construct and operate water infrastructure to sustainably manage the large unconfined coastal aquifer in the Burdekin River Delta. The costs of constructing and operating the scheme has been fully funded by the growers and sugar millers. The scheme was initially operated as an aquifer recharge scheme capturing local rainfall runoff as well as diverting large volumes of water, from the Burdekin River, to percolate into the aquifer via a series of constructed channels, recharge pits and natural watercourses. The design of the replenishment scheme was based on historical climatic data and a geological investigation of the aquifer to ensure there was sufficient water to support industry and irrigated agriculture through long dry periods between natural recharge events.
Design and Methodology
The scheme has been successfully operating for over 50 years and now consists of 18 pump stations and over 320 kilometres of channels, pipelines and natural lagoons. The scheme is operated on a conjunctive use approach with approximately 650 metered surface water pumps taking water from the distribution system and approximately 1800 groundwater production bores accessing the aquifer.
LBW on average pumps approximately 210,000 ML per annum from the Burdekin River and utilises rainfall and irrigation runoff, which is captured across the 76,000 hectares, for aquifer recharge and water delivery. In a dry year, the volume pumped from the Burdekin River by LBW can be as high as 290,000 ML.
LBW has successfully maintained aquifer levels over the years by adjusting its pumping and recharge operations according to water levels within the aquifer and general water demand as opposed to a strict monitoring of the volumetric usage within the area.
Original Data and Results
Measurements taken from monitoring bores within the Burdekin Delta document the changes in groundwater levels and water quality over time.
Conclusion
While the strategies deployed to manage the aquifer quality and level have been successful across the last 50 years, a large dependence on frequent periodic natural recharge events remains critical to the sustainability of the scheme. A change in the severity and/or duration of dry periods and natural river flow events would require a rethink on how the scheme is managed into the future. Impacts associated with sea level rises also need to be understood and factored into future management strategies.