South East Queensland is rich in environmental diversity. To safeguard our natural assets, it is important to understand the different kinds of activities and factors that cause the environment to change. Environmental pressures can arise from agricultural production, extraction of minerals, changes to rainfall patterns, the way we use water, and other activities.
Utilising science-based modelling studies and other tools, Healthy Land and Water has identified a range of pressures for South East Queensland, including:
South East Queensland’s warm climate, beaches and rainforests make it a popular destination for people all over the world looking for an easy and enjoyable lifestyle.
Not surprisingly, the population of our beautiful region has been steadily increasing over the past two decades, and as it becomes more world-renowned, this is set to grow even further over the coming years.
Population growth brings many positives to the economy and creates a bustling and lively community. However, a growing population also has an impact on our environment, including through land use and new developments, the consumption of natural resources and the generation of waste.
Managing the impacts of population growth is key to conserving the assets that make South East Queensland such an attractive place to live. Careful planning of urban and rural areas and the minimisation of litter and sediment pollution are all critical if we are to protect our natural environment in the face of increasing pressures.
Did you know?
- The population of South East Queensland makes up more than 70% of the state’s total population;
- South East Queensland’s population is set to grow by up to 2.2 million people over the next three decades to around 5.5 million people;
- A rising population means more land is made available for development, while our suburban areas experience higher density, placing pressure on wildlife, landscapes and waterways.
The health of South East Queensland’s waterways is affected by increasing amounts of mud or sediment entering our creeks, rivers and marine environments.
Erosion is the primary source of sediment pollution in our waterways and is most commonly caused by:
- Unstable river and creek banks;
- Mismanaged urban construction sites that expose large amounts of soil, which is easily eroded during times of rainfall.
Why is sediment an issue?
Sediment reduces water clarity and contains pollutants such as nitrogen and phosphorus, which threaten livelihoods and industries that rely on healthy waterways. Sediment also smothers aquatic plants, such as seagrass, reducing the amount of food available for turtles, dugongs and fish.
In addition, when large amounts of sediment are washed off the catchments and into our dams, it places an extra burden on our water treatment processes and affects the ability to produce quality drinking water.
Sediment pollution is particularly bad during times of heavy rainfall. For example, during the January 2011 and 2013 floods:
- Over 20 million tonnes of sediment washed off the land and into our waterways;
- The retail value of this soil if purchased from a landscape supplier would be more than $1 billion;
- The region’s largest water treatment plant at Mt Crosby was forced to shut down due to the amount of sediment entering the plant from the Brisbane River.
Waterway litter, particularly plastic, is a growing concern in South East Queensland. Not only is it ugly, it also causes serious harm to marine animals and can end up in the food chain.
In Moreton Bay, 30% of marine turtle deaths is caused by ingestion of plastics, with an additional 6% of deaths caused by entanglement in discarded fishing lines and derelict fishing nets.
Current research shows that endangered sea turtles are consuming more plastic than ever before, with green sea turtles twice as likely to ingest plastics today than in 19851.
Entanglement in discarded fishing gear also poses a serious risk to turtles, seabirds, whales, dolphins, dugongs, fish, crabs and numerous other species.
Waterway litter is a highly visible form of environmental degradation and is considered by most residents of South East Queensland to be an important issue on the public agenda. In the most recent 2015 Healthy Waterways community survey, litter was identified by the majority of respondents as the top factor that negatively affects waterway health in South East Queensland.
Did you know?
- According to the CSIRO, approximately three-quarters of the rubbish along the Australian coastline is plastic.
- Most marine litter is from Australian sources, not from overseas as is sometimes thought, with debris concentrated near urban centres.
- The density of plastic in the marine environment ranges from a few thousand pieces per square kilometre to more than 40,000 pieces of plastic per square kilometre near urban centres.
 Schuyler 2012
South East Queensland is the fastest-growing region in Australia with the population heading towards eight million by 2044*. The increased demand for water supply, infrastructure, agricultural land, as well as recreation and tourism facilities, places greater pressures on our landscapes and waterways.
Clearing vegetation in urban areas to meet the increased demand for major infrastructure like housing developments and shopping precincts introduces impervious or hard surfaces to a catchment area, such as roads and roofs.
During heavy rainfall, large amounts of stormwater travel across these hard surfaces at high speed, carrying a range of pollutants, including sediments and nutrients, and dumping these directly into our creeks and rivers.
The movement of water at high speed through these creeks and rivers leads to greater scouring of banks, which further increases the amount of sediment in the water. Subsequently, soils can be carried long distances, eventually ending up in our oceans with serious implications for marine life.
Unless land management and development control practices are improved, the additional urban areas that come with population growth will continue to increase the pollutant loads entering our waterways.
In rural areas, the deterioration of creek banks and gullies also needs to be reversed to safeguard aquatic ecosystems and water supply, as well as the recreation and food production capacities of the catchment.
The modern water cycle has been drastically altered from our historical depiction of forested catchments, regular rainfall, average water demands, and sufficient environmental flows.
Nowadays, the water cycle is more 'unconventional' with variable rainfall and a rise in the use of water harvesting technologies, such as wastewater reuse, desalination plants, and stormwater capture, leading to dramatically reduced environmental flows.
Climate variability poses a risk to our water supplies via three main pressures:
- Increased rainfall variability and intensity leading to increased flooding risk;
- Decreased, less frequent rainfall leading to extended durations of drought;
- Warmer temperatures increasing evaporation from catchments and reservoirs.
Extreme weather challenges
Most scientists agree that climate change will bring with it a range of extreme weather challenges, including prolonged drought and more intense rainfall events, leading to flooding.
Drought is a natural part of Australia’s variable and changing climate however periods of drought are likely to get worse in the coming years as rainfall patterns are altered. South East Queensland is one of the areas that will be hardest hit by drought, with the frequency and extent of exceptionally hot years and years with lower soil moisture likely to increase in the future.
Agriculture in Queensland has been valued at over $9 billion*, bringing enormous benefits to our local economy. But higher temperatures and levels of evaporation associated with drought have a negative impact on local water supplies, the preservation of soils and pastures, and the availability of feed for livestock. These pressures can disrupt cropping and harvesting schedules and lead to reductions in breeding stock. In turn, this increases the price of produce to the consumer with implications for the economy.
South East Queensland’s sub-tropical climate makes it prone to flooding events. When it rains, sediment, chemicals and litter are washed into stormwater drains and carried to our waterways, where they threaten aquatic and marine ecosystems.
At least half of South East Queensland's 48,000 kilometres of creeks and rivers have been identified as requiring critical repair and restoration1, highlighting the need for further investment in our waterways. This was exacerbated during the January 2011 and 2013 floods, when millions of tonnes of sediment washed off the land and into Moreton Bay.
* Hon. Tim Nicholls, Queensland Treasurer and Minister for Trade - 29 September 2014
1. Bunn S.E., Abal E.G., Greenfield P.F., Tarte D.M., Saxton N.E 2008. Linking science, monitoring and management to improve the health of waterways in SEQ, Australia. 4th ECRR Conference on River Restoration