We looked at how altered water flow regimes in the Murray-Darling Basin impact on its aquatic ecosystems, in order to support sustainable management. New tools are available for characterising freshwater ecosystems, optimising the delivery of environmental flows and measuring ecosystem response.

The challenge

Freshwater ecosystems under threat

Rivers, lakes, wetlands and other aquatic ecosystems in many regions of Australia have suffered severe degradation from the combined effects of river regulation and drought. The prolonged drought of 2000-2009, coupled with water extraction, produced the driest conditions on record, and coincided in a dramatic decline in the condition of aquatic ecosystems throughout the Murray-Darling Basin.

Our ability to protect, restore and sustainably manage these ecosystems and the biodiversity within them, in line with the objectives of the Water Act 2007, is limited by a lack of information about how changes in flows affect these ecosystems and the organisms within them. There is an urgent need for long-term, whole of system, integrated ecosystems science to provide decision-makers with the information needed for sustainable water resource management in Australia.

Our response

Bringing Australia's leading freshwater ecologists together

We formed the Ecological Responses to Altered Flow Regimes Cluster to bring together Australia’s leading freshwater ecologists to develop the science to underpin improved environmental monitoring and modelling.

The Cluster partners include:

  • Griffith University
  • The University of New South Wales
  • Monash University
  • Charles Sturt University
  • La Trobe University
  • Arthur Rylah Institute for Environmental Research.

Our researchers classified and mapped freshwater ecosystems in the Murray-Darling Basin as a first step in understanding ecosystem responses to flows. The Murray-Darling Basin aquatic assets and environmental attributes geodatabase was created to undertake this work.

We quantified the effects of water resource development and changes to flow, which vary from region to region across the Murray-Darling Basin. Regulation of flows by large dams has a major impact on freshwater ecosystems but bores, farm dams and levees are also a significant issue in many parts of the Murray-Darling Basin.

Environmental water returned to Cherax Swamp in the Murrumbidgee catchment

Our research indicates how and where these impacts can be addressed through environmental flows. We estimated the proportion of each type of aquatic habitat that can be watered from regulated river flows and the impact this is likely to have on key aquatic species.

We have also used optimisation modelling to provide water managers with tools for planning the delivery of environmental flows to achieve the best outcomes for freshwater ecosystems.

Our team has identified robust indicators that are responsive to flow alteration for monitoring the success of environmental flow interventions – these will prove useful in measuring success of environmental watering in the future.

The results

New knowledge and tools for monitoring environmental flows

Our partnership has generated new knowledge about ecosystem responses to environmental flows and developed a range of tools to support sustainable water resource management, including:

  • classification and mapping of freshwater ecosystems in the Murray-Darling Basin and threats to their ecological condition
  • flow-ecology response models for different components of the flow regime
  • optimisation modelling of environmental flows to inform the delivery of environmental water allocations
  • methods for monitoring and assessing the outcomes of environmental watering.

Final reports

Sub projects:

  1. Optimisation models for environmental flows and freshwater conservation planning
  2. Flow regimes and ecological assets
  3. Flow dependent ecological responses
  4. Assessing aquatic ecosystem condition and trend

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