While the Murray-Darling Basin is divided into 22 catchments we often think of it in 2 distinct parts – the northern Basin and southern Basin. These 2 parts are different in many ways. They have different climate conditions, topography and consumptive needs. These differences mean that the northern and southern parts require different water management arrangements to achieve sustainable and productive river systems.
The northern Basin covers over 500,000km² across northern New South Wales and southern Queensland where water runs into the Darling River and then flows down into the Murray River in the southern Basin.
The northern Basin differs from the southern Basin in many ways:
Climate, topography and In-flows
The northern Basin is home to diverse ecologies with large parts of the landscape being flat, dry and typically hotter than most of the southern Basin.
Most of the rainfall is in the east or over mountain ranges with less rainfall on the drier, flatter areas where it can quickly evaporate and never make it into the river systems.
Lots of evaporative loss occurs in the northern Basin. Of all the water that falls only about 5% flows into the rivers.
This makes in-flows to the rivers highly variable and unreliable.
The northern Basin is home to many different people, places, industries and agricultural businesses who rely on water for their wellbeing and livelihood.
The varying in-flows create a boom then bust cycle in communities and in irrigated agriculture where water availability varies greatly from year to year.
Water management arrangements
These unique conditions mean that ensuring sustainable rivers in the northern Basin requires different management techniques from the southern Basin where there is more water reliably available to be shared between the environment and consumptive use.
The Murray-Darling Basin Plan and the northern Basin
During the creation of the Murray-Darling Basin Plan less was known about the northern Basin and what was needed to improve its health. The Basin Plan dealt with this by creating a requirement for the Murray-Darling Basin Authority (MDBA) to conduct a review of the Basin Plan settings in the northern Basin to make sure they were appropriate and could deliver for the environment.
Northern Basin review
The Northern Basin Review was conducted by the MDBA in 2016. The MDBA suggested amendments to the Basin Plan to account for the improved understanding of the northern Basin. The amendment reduced the volume of water that needed to be recovered from consumptive uses by 70GL and also introduced a range of other measures that could support the environmental health of the northern Basin, known as the Toolkit measures. The amendment passed in 2018.
Northern Basin measures
A number of measures are underway to support the health of the northern Basin. These measures have a focus on complementing Basin Plan implementation by addressing the specific water management challenges faced in the northern Basin to achieve environmental and community outcomes.