Northern Basin

The northern Basin work program focuses on improving the information used to develop sustainable diversion limits (SDLs) in the north. The Northern Basin Review is a key part of this work.

The northern Basin is different to the southern Basin. It is drier and much flatter. It receives most of its rain during summer, while the south receives most of its rain in the winter. The rainfall in the north is not only lower, but also more inconsistent than in the southern Basin. The north also faces higher levels of evaporation, and is largely unregulated.

An aerial photo of farmland near the Warrego River, northern New South Wales.
Photo by Tom Chesson (2007).
Farmland near the Warrego River, northern New South Wales.

These differences mean that we need to approach implementing the Basin Plan in the north differently.

The northern Basin work program aims to achieve a healthy, working northern Basin through the integrated management of water resources. The work program has 6 key aims:

  • achieve positive social and economic outcomes
  • achieve sensible water recovery and effective use
  • identify the best environmental science
  • ensure communities have confidence in the implementation of the Basin Plan
  • establish reliable monitoring and evaluation methods
  • recognise cultural flows.

Northern Basin Review

The Northern Basin Review is a part of the work program. Under the review, we are carrying out further research and investigations on the basis for the sustainable diversion limits in the north. We are looking at the Condamine–Balonne local reduction and the northern-shared reduction amounts.

The expected outcomes of the review are:

  • improved information on achieving environmental outcomes and social and economic costs and benefits for different diversion limits
  • recommendations about possible improvements to Basin Plan settings in the northern Basin
  • advice on how best to recover the remaining target for environmental water.

The review explores 3 themes of the work program: environmental science, social and economic assessments and water recovery modelling.

Why is the review being done?  

The Basin Plan currently sets 3,468 GL as the limit of water that can be extracted across the northern Basin on average per year. This is 390 GL or around 10% less than the amount that was taken before the Basin Plan.

The current water recovery target of 390 GL for the north is made up of 247 GL for local catchments plus a further 143 GL to be found across the catchments fordownstream needs.

In finalising the Basin Plan, the MDBA agreed to do further research and investigations on the settings of the northern Basin to see if there is a case for changing them. While the science was the best available at the time, the MDBA felt a review provided a chance to fill some of the gaps in our information.

The review encompasses the northern Basin region as a whole, with a focus on the Condamine–Balonne and Barwon–Darling catchments for the environmental science projects. Once we have a better understanding of environmental water needs, we can then look at different Basin Plan settings to see how often these water needs can be met without creating undue social and economic affects.

Environmental science

The environmental science component will provide additional information and data about the relationship between flows and the environment's response in particular for vegetation, fish, and waterbirds in the northern Basin.

We will be working on the following:

  • floodplain inundation mapping across the lower Balonne and Barwon–Darling systems
  • floodplain and wetland vegetation mapping within the Darling River system
  • waterhole mapping and analysis of persistence in the lower Balonne and Barwon–Darling systems
  • water requirements for floodplain vegetation in the lower Balonne and Barwon–Darling systems
  • review of waterbird breeding response to flow at Narran Lakes
  • response of fish to changes in flow.

Photo by Josh Smith. Courtesy of the New South Wales Office of Environment and Heritage.
The Narran and Gwydir wetlands in flood

Water recovery modelling

The hydrological modelling component will be used to estimate changes in flow and environmental outcomes for a range of water recovery scenarios.

We will be working on the following:

  • northern standard scenario using existing environmental water requirements
  • water recovery in the Condamine–Balonne using existing environmental water requirements
  • water recovery for the northern zone shared reduction
  • water recovery scenarios for the entire northern Basin (using revised environmental water requirements)
  • scenarios for informing the split of the 143 GL northern zone shared reduction between the northern valleys (using revised environmental water requirements).

Social and economic assessments

The social and economic component will assess the impacts of selected water recovery and apportionment scenarios for primary producers and the flow-on effects for the communities of the northern Basin.

We will be working on the following:

An Aboriginal sociocultural survey was undertaken in December 2015 to find out about the importance of environmental water to Aboriginal Nations in the north of the basin and to feed this into the decision making around the Northern Basin Review.

The research shows that Aboriginal populations in the north of the basin see a direct relationship between environmental watering and improved Aboriginal well-being. It has quantified the importance of environmental water to this population group for the first time. At a regional scale of landscape, as defined by the three surveyed communities (Brewarrina, St George and Dirranbandi), 202 respondents assessed environmental water to have a 92% importance rating to their sociocultural Assets (‘Capital Assets’) which are recognised as the determinants of viable socioeconomic development.

The report outlines the development of the survey tool and presents the survey findings in relation to the importance of environmental water to Aboriginal Nations in the north of the basin.

Timeline for completion

We will complete the review in four phases:

  • phase 1– research and investigations – late 2015. This phase includes the completion of the environmental science, hydrological modelling and social and economic projects
  • phase 2 – integration of results – mid-2015 to mid-2016. This phase will see the results under the 3 themes integrated for several water recovery scenarios
  • phase 3 – consideration of results and decision making – from late 2015 to late-2016. This phase will see the inputs from the 3 themes analysed. Based on this analysis we will consider the setting of the northern Basin limits, including the volume of the northern-shared reduction and the Condamine–Balonne local reduction
  • phase 4 – statutory – from 2016 and throughout 2017. This phase will follow the process for amending the Basin Plan, set out in legislation. This includes inviting states and the broader community to make submissions, considering submissions and preparing a consultation report. This process takes about 12 months.