Engagement – February 2024

A. The Commonwealth Government is required to monitor and report to the Ramsar Convention Secretariat under Article 3.2 of the Ramsar Convention, if the ecological character of any Australian Ramsar wetland has changed. This is done through partner states including NSW. As such DCCEEW Biodiversity, Conservation and Science (BCS) group have a policy to follow the 'National guidance on notifying change in ecological character of Australia's Ramsar Wetlands (Article 3.2)'. BCS or the Commonwealth have commissioned ecological character descriptions (ECDs) for numerous NSW Ramsar sites. These ECDs provide observed condition at 'a given point in time.’ If a case for a change in ecological character is submitted and then accepted by the Ramsar secretariat, we then need to develop a response plan to mitigate these changes. For example, an Article 3.2 response strategy has been developed for the Macquarie Marshes.

ECDs assess hydrological changes as part of a broader condition assessment at ‘a given point in time.’ Climate change impacts on hydrology are identified as one of the many threats and modelled or citable climate models are used in the development of ECDs where available. The resulting response strategies are then focussed on restoring ecological character, which will typically include restoring aspects of, but for availability reasons not all of the natural flow regime.

The ECDs are one form of assessment that aid this process, as they rely on information from many past and current commonwealth and state environmental monitoring programs. The current commonwealth-funded monitoring, evaluation and research program (Flow-MER) and the Murray Darling Basin Authorities’ The Living Murray (TLM) program are using existing data and generating new data to inform environmental water and Ramsar site managers.

A. Yes. We have recognised for some time now that we need to consider all temporal aspects of water availability in understanding outcomes, including extreme droughts and floods - as referred to in presentation - that we see in our climate data sets and everything in between. The long-term average often quoted is a measure of the relative wetness or dryness of different climate periods, but is not directly used to determine water sharing arrangements.

A. The degree to which climate models currently represent atmospheric and oceanic conditions that determine rainfall is an area of climate science we and others think is important to understand to inform us how reliable different models are. Climate science is evolving, and findings such as this will inform update and evaluations of climate models, and how these modelled projections can be used is an ongoing body of work, in the department, as well as nationally and globally.

We are currently examining how we can use the most up to date climate models for NSW (NARCliM 2.0). The driving global climate models used by NARCliM are a subset of all available climate models used in the IPCC assessments. This subset was selected after a rigorous assessment. However, as we know that climate modelling is a continually evolving our focus is on applying methods that are useful regardless of which climate model(s) we use.

A. That graph is sourced from climate snapshots that what is now the Biodiversity Conservation and Science division put out a number of years ago. It uses a subset of older  climate projections that what is available today. The graph was used for illustrative purposes.

While the graph does show that the median climate models show a slight increase in annual rainfall, It also shows the wide spread of modelled rainfall outcomes, ranging from significantly wetter to significantly drier. This demonstrates how important it is that we take a risk-based approach to decision making, as we cannot rely on the median modelled outcome being the one which occurs.

That is why we are working to build a framework which can deal with the range of variability from the range of climate models.

A. We are currently working on the technical analytical aspects of the overall approach, and outcomes from that analysis will inform other assessments and engagements we need to have before we are in a position to make recommendations.

The impacts of evaporation are significant in terms of water availability across the whole of the catchment, not just confined to riparian zones. However, there are a number of other recognised benefits to improved riparian zone management, including ecological outcomes, such as increased habitat and shading.

These benefits have been recognised in a number of the Regional Water Strategies developed across NSW, with actions identified across government to achieve catchment management outcomes. These include:

• A Northern Rivers Watershed Initiative has been established through the Northern Rivers Joint Organisation of Councils to improve water security and catchment health. The initiative will ensure a joined-up approach to catchment management modelling and natural flood mitigation to improve riverine health and reduce flood risk.
• The department will continue to work with Local Land Services to implement the Riverbank Rehabilitation Project at critical sites across the state and provide guidance to landholders on best practice management to support the regeneration and protection of waterways and estuaries.

A further initiative to minimise the impacts of livestock on riparian areas to improve water quality and native fish habitat is the NSW Fencing Northern Basin Riverbanks Program. The program led by Local Land Services, provided landholders along priority reaches in the northern Murray-Darling basin with funding assistance to undertake on-ground projects. In total, landholders signed up to construct 260 kilometres of fencing to protect around 13,000 hectares of riparian land and undertake around 2,000 hectares of weed and erosion control works.

A. We are looking at striking a balance between security for water users such as towns and environment as well as the ongoing viability of our industrial and irrigation users. Adaptive management is one of the tools we will be using to try and make sure we find the right balance.

A. The key benefit of using the different sources of climate information (e.g. paleo, stochastic, and climate models) is that we can do these sorts of calculations. Within the Paleoclimate informed stochastic datasets, it is likely that these extreme events do occur more frequently than indicated in instrumental records. There are two main reasons for this:

• The paleostochastic data represents the range of variability captured within the paleoclimate evidence – and this shows that there were previous droughts which were more severe than have occurred during the recorded data,
• The paleostochastic data provides a 10,000-year dataset compared to only 130 years of historic data. As a result, there is an increased chance that we have captured the range of extremes within this longer period.

Some examples of this can be seen within the Regional Water Strategies.

While longer records do exist in a small number of locations in NSW, we require data which provides adequate coverage across all of NSW.  The spatial coverage of rainfall stations was not comprehensive prior to around 1890. We use rainfall from the SILO gridded climate dataset, providing data from 1890 throughout the whole of NSW.

We have been committed all the way through to making sure we have rigorous science and use robust decision-making tools. We engaged an independent expert panel led by the Office of Chief Scientist and Engineer in the early stages of this work and have been endeavouring to follow recommendations from their report to continue to improve our work. We have advocated for and supported expert advice for basin-wide hydroclimate approaches in the Murray Darling Basin and will be looking at a similar independent expert approach to make sure that our work continues to be scientifically rigorous and defensible.