Floodplain harvesting is when the water that flows across the floodplains during a flood is collected and used later.
Overland flow refers to water that runs across the land after rainfall, flooding, or after it rises to the surface naturally from underground. Capturing this water on a floodplain is referred to as overland flow development or floodplain harvesting.
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Key facts
Floodplain harvesting has been regulated under the Cap system since 1995, although it has never been fully measured and accounted for.
As floodplain harvesting is licensed and accounted for, it will be incorporated within the sustainable diversion limits established under the Basin Plan. This will see the sustainable diversion limit increase.
Any change to floodplain harvesting regulations will mean the water limits and water resource plans will need to be updated to incorporate these changes.
This does not mean more water is available for use, this water is in use already – it is just ensuring that it is robustly measured and can be monitored to ensure use does not grow over time.
Any changes must be based on best available or improved information before they are incorporated into the Basin Plan.
When the Basin Plan was established, the Murray–Darling Basin Authority (MDBA) had a good understanding of how much water needed to remain in the river system to improve the health of our environment.
The MDBA, New South Wales and Queensland also knew some types of water use needed to be better accounted for. In the past it has been hard to accurately estimate how much floodplain water has been used or ‘harvested’, and therefore this water use has not been accounted for in the rigorous way other water use is accounted for.
Accounting for water is the first step in enabling governments to put in place compliance measures, which will allow them to monitor the amount of water that is being used.
Licencing floodplain harvesting use means that any growth in use is restricted and, in some cases, can be wound back to ensure water use remains within the legal limits. Licencing improves compliance and accounting of water use in New South Wales and Queensland.
Floodplain harvesting has been regulated under the Cap system since 1995, and the proposed changes mean usage will typically now be restricted to the levels used in the year 2000. Doing so will make these limits consistent with the Basin Plan, existing arrangements for other water use, and represent a lower level of overall water use than was in place under the Cap in 1995, which is considered sustainable.
Work is underway in New South Wales and Queensland to better understand how much water is harvested from floodplains now, and how much was being harvested prior to the Basin Plan.
At its heart, the Basin Plan sets the amount of water that can be taken from the Basin each year, while leaving enough for our rivers, lakes and wetlands and the plants and animals that depend on them.
The MDBA welcomes the proposed changes from New South Wales and Queensland governments. Measurement and compliance of floodplain harvesting must be improved – so over time, we can ensure this use does not exceed the limits.
It is important that any change to licenses and new improved information about water usage is reflected across the whole water management system and in the day-to-day operation of the Basin Plan.
It is expected that as licensing, monitoring and accounting arrangements are improved, the total amount of water used through floodplain harvesting will be managed within the limits established under the Basin Plan.
Download the MDBA's Floodplain harvesting fact sheet
Changes in New South Wales
The New South Wales Government has sought input from the community on licensing floodplain harvesting as part of the regulated system with all other water licenses.
The New South Wales Government is proposing that water harvested from floodplains will be limited to ensure that the amount of water taken in a valley does not exceed levels used in the year 2000. This is in line with the baseline diversion limits under the Basin Plan. The New South Wales Government says there has been growth in floodplain harvesting across some parts of the New South Wales northern Basin that has caused an increase in water diversions above legal limits. As a result, licenced take will need to be reduced for users in some valleys to remain within legal limits – this is a decision for New South Wales.
As floodplain harvesting is regulated and measured, sustainable diversion limits in New South Wales will change to properly include floodplain harvesting along with other forms of take.
Over the past few years, New South Wales has considered data from hydraulic models, gauged streamflow, remote sensing, satellite imagery, aerial photos, flood and licensing records, as well as survey and on-ground inspection data.
This work was part of the Australian Government funded ‘Healthy Floodplains Project’ in New South Wales to improve data and planning for floodplain harvesting.
New South Wales Independent Reviews
An independent review was undertaken in 2018–19, finding improvements are needed to accurately model floodplain harvesting in New South Wales. Further work is underway to ensure water sharing plans and water resource plans accurately represent floodplain harvesting use.
The independent review also recommended increased community engagement to enhance community input and understanding. The New South Wales Government is committed to improving modelling and engagement to provide certainty that the floodplain harvesting policy is robust.
The New South Wales Government has undertaken, and continues to, conduct public consultation to provide information to the community on licencing floodplain harvesting as part of the regulated system with all other water licences.
The MDBA has commissioned independent reviews for some areas to determine the accuracy of New South Wales estimates of floodplain harvesting. It is expected that New South Wales will propose improved estimates of baseline diversion limits associated with floodplain harvesting through water resource plans.
More information
Changes in Queensland
Queensland is undertaking a different process to monitor and measure floodplain harvesting and overland flows. Queensland placed a moratorium on additional floodplain harvesting development in 2000 and has prevented any growth in use since that time by using a combination of authorisations and licences.
Since the moratorium was put in place and additional development ceased, Queensland has issued licences and implemented measurement programs in some places like the Lower Balonne, where floodplain harvesting is measured using storage meters and other on-farm measuring devices.
For all other areas, works-based authorisations ensure that there is no increase in the capture of floodplain harvesting water beyond 2000 levels.
If an authorisation is no longer able to prevent growth (such as when an irrigator applies for a trade, or for new works on their property) then it is replaced with a volumetric licence.
Additional work is now planned through the Queensland Rural Water Management Program to enable improved measurement and monitoring of the use of overland flow.
Queensland has also recently committed to the full measurement and licensing of the Border Rivers and Moonie floodplains by 2022.
Once floodplain harvesting is fully measured and licensed, water limits in Queensland will be revised to capture the best information.
New information on floodplain harvesting will need to be included in updated estimates of baseline diversion limits, which are outlined in water resource plans. This means water resource plans will change over time, as the understanding of floodplain harvesting improves.
More information
Next steps
The New South Wales Government has released its Floodplain Harvesting Action Plan as the plan to address all recommendations from the independent review. The New South Wales Government has incorporated floodplain harvesting into water resource plans.
Water resource plans include an interim baseline diversion limit for floodplain harvesting. The interim limit will be assessed by the MDBA and is based on the best available information, including updated models. Water resource plans need to include methods to assess whether there is growth in use beyond the allowable levels for floodplain harvesting and will have rules to reduce take if excess use occurs.
Water resource plans also need to include commitments to fully implement the New South Wales Floodplain Harvesting Policy, including installing measurement devices and licencing of storages. Once licences and measurement devices are in place, the New South Wales government will submit updated water resource plans to the MDBA to ensure this new information and regulation changes are reflected across the whole water management system.
It is expected that overland flows in the priority floodplains in Queensland will be licensed by 2022.
The Queensland Government continues working with floodplain harvesters to extend measuring and licensing.
Once these changes are complete, the Queensland Government will need to submit new information and changes to the MDBA, and these will need to be incorporated in the water limits and water resource plans.
