- Most of Australia’s rainfall evaporates back into the atmosphere, with only 10% ending up in rivers, lakes and groundwater reserves.
- Surface water (water in rivers, streams and lakes) is NSW’s most important source of freshwater.
- These freshwater sources are important for NSW’s environments, wildlife, people and industries to survive.
- Climate change is warming temperatures, changing rainfall patterns, and increasing evaporation, which is reducing water availability and affecting water quality in parts of NSW.
- The NSW government has developed regional water strategies to help NSW adapt to future changes in its water resources. These strategies consider the latest climate evidence and climate change modelling data, to see how NSW water resources might be impacted by climate change.
The importance of water resources in NSW
NSW is Australia’s most populated state and contains large agriculture and tourism industries. It is also home to important wildlife and ecosystems. All of these depend on a secure source of freshwater.
In NSW, around 80% of our water supply is taken from surface water – water found in streams, rivers and lakes. The remaining 20% is drawn from groundwater – which are natural underground stores of water. Water is interchanged between the surface and groundwater which are connected. There are times when groundwater is recharged from the surface, but also times when the groundwater provides baseflows into streams.
Water resources in NSW are essential for urban water supply. As populations grow in NSW’s major cities, more water is needed to support them.
In regional NSW, water is also a major part of many livelihoods, with agricultural businesses and jobs depending on how much freshwater is available.
NSW freshwater sources are also valued for tourism, recreation and cultural activities.
NSW’s ecosystems such as rivers and wetlands depend on freshwater. Surface water supports aquatic plants and animals, as well as habitats and species in surrounding floodplains. Natural flooding events are needed to keep these ecosystems healthy.
Groundwater can support entire ecosystems, such as natural springs that support a range of plants and animals in arid parts of NSW.
Agriculture is one of Australia’s largest industries and uses the most water of any Australian industry. Without long-term access to freshwater, Australia’s agriculture industry would decline, affecting the economy, jobs and food production.
NSW’s tourism industry relies strongly on healthy ecosystems to attract tourists. Changes to our water resources can damage tourism businesses. This was seen in 2008 with an estimated loss of $70 million in the River Murray region due to fewer visitors during drought.
How water resources are affected by climate change in NSW
Climate change is increasing temperatures and affecting rainfall, evaporation and climate systems in NSW. These changes will affect the quality and availability of NSW water resources. Pressure on NSW water resources will also increase with the combined impacts of climate change and a growing population.
Climate change is likely to reduce the amount of surface water available in NSW. Warming temperatures and changes to climate patterns are predicted to:
- increase evaporation from waterbodies, and evapotranspiration from plants
- change the influence of key climate drivers, such as east coast lows, El Nino – Southern Oscillation, Indian Ocean Dipole, Interdecadal Pacific Oscillation and Southern Annular Mode. Changes to these drivers will affect the frequency and magnitude of rainfall events over NSW.
People access groundwater using bores, plants access groundwater when their roots meet the water-table underground, and ecosystems access groundwater when the water-table reaches the surface through springs or seeps up through riverbeds.
Groundwater is replenished as rainfall seeps into the ground (a process called groundwater recharge). The processes for recharge include direct infiltration from rainfall onto the land surface, or infiltration from surface water.
Both of these processes are expected to be affected by climate change. In some cases, these processes may reduce recharge, for example because of decreases in rainfall. However, some of the climate change projections suggest that we may see an increase in the magnitude and intensity of rainfall events, and if these occur in close succession - may increase recharge.
More research is required to determine how these key recharge events will be impacted by climate change and how our groundwater supplies will be affected.
Poor water quality has far-reaching impacts on people, communities, wildlife, industries and the economy.
Climate change is causing changes to our weather and oceans which can reduce the quality of NSW water resources, including:
- sea level rise, which pushes salt water further up coastal waterways, contaminating freshwater
- more extreme storms and rainfall events, which erode and washes soil into waterways, reducing water quality
- warmer waters in storage facilities such as dams, which can increase the risk of bacterial or algal growth
- drought conditions, which make naturally occurring salts more concentrated in waterways through evaporation and a decrease in the frequency of high flow events which ‘flush’ out salts.
These impacts can make water resources unsuitable for human water supplies and agriculture, and damage freshwater ecosystems.
Adapting to changes in water resources in NSW
Understanding how climate change may affect NSW water resources helps governments and decision-makers ensure the state’s long-term water supply.
The NSW Government manages surface water and groundwater across the state, and is developing regional water strategies to help NSW adapt to future changes in its water resources. These strategies consider the latest climate evidence and climate change modelling data, to see how NSW water resources might be impacted by climate change. The strategies were developed in partnership with water service providers, local councils, communities, Aboriginal people and other stakeholders across NSW.
- designing storm water infrastructure to withstand the more extreme (but less frequent) rainfall and storm events that climate change is likely to bring
- plan long-term water supply strategies to account for reduced water availability.