Water Theme

The Great Southern is a growing region with increasing demands on its water resources. Managing water resources involves balancing economic needs and security of water supply against environmental needs and ecological risk. It is important that rivers and wetlands with high ecological values are protected. Agricultural development has already caused salinisation of some of the major river systems and there are a range of stressors on wetlands and estuaries. Declining rainfall is causing reductions in streamflow. Priority research to improve the management of aquatic systems in the Great Southern includes research on groundwater systems, improving efficiency of use of water resources and understanding and managing off-site impacts of agriculture and other development.

Groundwater

Background

Many residents in the Great Southern are dependent on groundwater for a significant proportion of their water supply. As demand for groundwater increases, the risk of adverse impacts on groundwater quality and groundwater dependent ecosystems also increases. Groundwater dependent ecosystems include wetlands, systems dependent on streams fed by groundwater, ecosystems in caves and aquifers (such as stygofauna) as well as some terrestrial ecosystems. There are a number of threats to the quality of groundwater including: seawater intrusion on the coast; pollutants such as nutrients, pesticides or other chemicals; and changes in geochemistry as a result of development. Therefore in order to improve the management of non-saline groundwater in the Great Southern, research to increase the understanding of groundwater systems and their dependent ecosystems is a priority.

NRM problem: Changes in land use or management and over extraction of groundwater can impact adversely on groundwater ecosystems and water quality.

Research objectives

  • Understanding the impact of current and future groundwater abstraction and climate change on groundwater dependent ecosystems
  • Improving understanding of groundwater systems and their sustainable yield

Efficient Use of Water Resources

Background

The Great Southern is experiencing increasing demand for water and in some smaller towns there are often shortages of potable water. New water supply options need to be climate independent. Desalination is a climate independent source but is relatively high cost and has a high demand for energy. Increasing water supply has environmental risks and it therefore also important to increase the efficiency of use of current supply. Strategies that include wastewater reuse, decreased losses and increased household and agricultural water efficiency are an important part of water resource management.

NRM Problem: Improving water resource efficiency and reducing the environmental impacts of developing new water resources.

Research objectives

  • Understanding and overcome barriers to the adoption of increased water efficiency measures and water re-use
  • Finding cost-effective water resources for rural towns
  • Improving wastewater treatment and disposal
  • Increase effectiveness in water collection, storage and use, particularly through combating loss by leakage and evaporation

Wetlands

Background

Wetlands are important ecosystems in the Great Southern. They also provide habitat for migratory birds and a range of ecosystem services such as flood protection and 18 filtration of nutrients and pollutants. Changes in hydrology, loss of vegetation, increases in nutrients, and invasive species are all threats to wetlands in the region. Although there is a national and international focus on Ramsar wetlands because of their importance for migratory birds, many wetlands in the Great Southern have very high ecological or recreational values. There is therefore an urgent need to evaluate and prioritise wetlands for protection and management. This requires more knowledge about wetland systems and better classification and mapping.

NRM problem: There are a number of threatening processes leading to degradation of potentially important wetlands in the region.

Research objectives

  • Improving understanding of the hydrology of important wetland suites and the implications for ecological restoration
  • Mapping and classification of wetlands with assessment of wetland condition, benefits and values

Acidification, Causes and Impacts

Background

Agriculture and urban development can cause acidification of wetlands, groundwater and rivers. Lowering the groundwater table by over-abstraction can lead to the development of acid-sulphate soils and acidification of groundwater. Groundwater in much of the Great Southern is naturally highly saline and can be naturally acidic, particularly in the more inland areas in the Zone of Ancient Drainage. In these areas there is a problem with disposal of acidic brines from deep drains or ground water pumping used for management of salinity on agricultural land. The high ecological values of wetlands and estuaries on the south coast could be at risk from acidic saline groundwater although the greatest risk is to aquatic systems on the central and eastern south coast.

NRM problem: Risk to ecological values from disturbances leading to acidification of water.

Research objectives

  • Understanding the processes of acidification in freshwater aquatic systems
  • Understanding the impact of water abstraction on potential acid sulphate soils
  • Understanding the link between acidification and eutrophication in aquatic systems
  • Understanding the impact of acidic brines on aquatic systems

Eutrophication

Background

Diffuse sources of nutrients from agricultural fertilizers are the main cause of eutrophication in the Great Southern. Sandy coastal soils with low phosphorus absorption can be a particular problem for phosphate losses. Annual crops and pastures also cause more recharge and run-off than perennials. The plant nutrients nitrogen and phosphorus are most bio-available in their dissolved inorganic forms. Phosphorus is difficult to measure because of its propensity to bind to sediment. There is evidence that both surface and sub-surface run-off contribute to excess phosphorus in aquatic systems. Sediments can bind and release phosphorus under different conditions. This increases the complexity of management strategies. Although there has been an increase in knowledge about eutrophication processes in the Great Southern there are still many important knowledge gaps. In the meantime increasing fertilizer efficiency is important for economic and environmental reasons.

NRM problem: Eutrophication of aquatic systems from diffuse agricultural sources of nutrients.

Research objectives

  • Improving the understanding of nutrient dynamics in catchments and streams
  • Improving knowledge about retention and release of nutrients by streams
  • Increasing the efficiency of use of phosphorus in coastal systems
  • Improving understanding of the risks, triggers and mechanisms of algal blooms in estuaries
  • Development of alternative low impact fertilisers for sensitive sites

Impacts on Aquatic Biodiversity

Background

Aquatic biodiversity and levels of endemism, particularly of invertebrates, are known to be relatively high in much of the Great Southern. Yet there have not been comprehensive surveys nor is there knowledge on how different species may respond to threats such as increases in salinisation or inundation, sedimentation, and climate change.

NRM problem: Changing hydrological regimes and increased sedimentation are impacting on biodiversity in aquatic systems.

Research objectives

  • Surveying and monitoring biota in selected aquatic systems in the Great Southern in order prioritise systems for protection or management
  • Understanding the off-site impacts of agriculture on biodiversity in aquatic systems

Land Use Management and Aquatic Systems

Background

Although there are many land use management tools designed to improve the health of aquatic systems, there are many gaps in knowledge about their impact. There is a need for better information to enable effective adaptive management. In particular it is important to use an approach that considers land management in catchments, wetlands, rivers and estuaries, in an integrated way.

NRM problem: Hydrological implications of changing fire regimes.

Research objective

  • Monitoring the effect of changing fire regimes on water quality and aquatic geochemistry

NRM problem: Degradation of waterways.

Research objectives

  • Understanding the impact of riparian management on water quality
  • Understanding priority areas for reducing recharge/discharge

NRM problem: Finding best practice management of plantations in order to improve the hydrological balance and water quality.

Research objectives

  • Finding appropriate vegetation cover to maximize hydrological benefits
  • Monitoring the impacts of removal of plantations on hydrology
  • Monitoring the impact of plantations on water quality

Climate Change and Aquatic Systems

Background

Climate change is already impacting on aquatic temperatures and water flows in the Great Southern and as global temperatures increase even higher water temperatures, lower flows and more extreme rainfall events are predicted. These changes are likely to interact with current stressors such as nutrients and hydrological change. Higher water temperatures are likely to increase eutrophication, more extreme summer rainfall events will increase sedimentation and turbidity, and in some streams there is likely to be increases in salinity as fresh water flow decreases. More intense and inappropriate fires are also likely to impact. Sea level rise is a potential threat to estuaries, coastal groundwater systems and wetlands. Differences in responses to changes in temperature, hydrology, aquatic chemistry and salinity are likely to lead to major changes in aquatic biodiversity. Predicting and monitoring these changes will improve opportunities to manage adaptation to climate change.

NRM problem: Climate change is a threat to aquatic biodiversity in the Great Southern. It will also interact with other stressors to compound the impacts on systems.

Research objectives

  • Monitoring the impact of climate change and the effectiveness of adaptive measures on aquatic systems
  • Understanding the vulnerability of different species, ecological processes and systems to climate change impacts
  • Finding ways to increase refugia and connectivity
  • Understanding the interactions between climate change and other stressors
  • Modelling and monitoring the impact of climate change on water resources
  • Monitoring the impact of land use change for carbon sequestration on waterways