The NSW Office of Water has developed and continues to maintain and use models to understand and assess the behaviour of a series of river systems in NSW. The models are used to help predict the impacts of current and future water management policy on the environment and water users across the state. The models are tools that support the Office policy development and by running a series of scenarios to understand the impacts of each the most optimum solutions can be identified. Outputs from the models also are used to support environmental and economic assessment of water management options.
The main river system model used by the Office for water sharing and management is the Integrated Quantity and Quality Model (IQQM). IQQM has been developed to assess the impacts of different management strategies on all water users. The models have been developed to simulate the major hydrological processes in river valleys, along with relevant management rules, and have been calibrated to match observed reservoir levels, diversions and flows over the calibration periods. The models are set up in such a way as to reproduce average long term behaviour of the river system for planning purposes and not specifically to reproduce individual daily flow behaviour in any particular year or forecast any future year.
IQQM models have been developed for most inland river basins and some coastal river valleys. The models can be utilised to obtain a range of information on simulated river system behaviour ranging from average summary statistics to specific event or sequence details. These models are used in NSW water sharing plans, for auditing NSW compliance with the Murray-Darling Ministerial Council Cap, for estimating baseline salinity condition of NSW rivers in the Murray-Darling Basin, together with a range of strategic and operational hydrologic matters.
The impacts of climate variability and climate change have been a particular focus of the Office and we have utilised a range of climate and hydrological modelling approaches to help translate estimates of rainfall and evaporation changes from climate change scenarios into impacts on the surface water regimes of river basins across NSW. The Office models also link with Queensland and Murray-Darling Basin Authority models where water management responsibilities overlap.
Major regulated river systems
The major regulated rivers in NSW are the Border Rivers (jointly managed by New South Wales and Queensland), Gwydir River, Namoi River, Macquarie River, Lachlan River, Murrumbidgee River and the Hunter River.
In 2009 the NSW Government published information on water reliability for NSW river valleys in the Murray-Darling Basin. View the report from the link below.
Since the 2009 report was published, there has been interest in the data used to generate the reliability plots, particularly with regards to inter-annual variability in water availability. The NSW Office of Water has now published, in an annual time-series format, the data that was used to generate the summary information in the 2009 report. View the information from the link below.
- Water availability in NSW Murray-Darling Basin regulated rivers – Appendix of annual data (PDF 3.3 MB)
Major unregulated river systems
Barwon/Darling River, Richmond River, Clarence River, Macleay River and Bemboka River.
The major processes that are simulated include:
- Flow routing in rivers, and irrigation channels, including branches, loops and tributaries
- Reservoir operation
- Urban water supply and other consumptive uses
- Wetland and environmental flow requirements
- Water use accounting systems
- Groundwater/surface water interaction.