The Murray-Darling Basin science

Understanding the impact of climate on water availability in the Murray-Darling Basin

Page 8 of 9

Challenge

The southern Murray-Darling Basin, where most of the water runoff is generated, has experienced a prolonged drought known as the Millennium Drought, from 1997-2009, which has placed immense pressure on the limited water resources.

This past rainfall decline can be partly attributed to climate change, however it is difficult to separate the climate change signal from the high natural variability.

Climate and water modelling indicates the southern Basin is likely to have 10 per cent less water on average (median result) in the next 20 to 30 years.

Despite the best science, there is a wide range of future water predictions, and water managers and policy makers need to build these possible futures into their plans.

Response

CSIRO climate and water scientists are working to provide more accurate predictions of future water availability to guide water planning and management through:

  • improving the characterisation and attribution of climate in south-eastern Australia
  • downscaling global climate model projections to provide catchment scale climate and hydrological modelling in order to predict climate change impact on future water availability. Climate Modelling Graph

Outcome

CSIRO has provided the Murray-Darling Basin Authority with advice on defining climate scenarios for use in its modelling to guide the development of the first Basin Plan.

Advice was provided on three aspects:

  • Climate baseline, based on the long 100+ years of observed historical data to describe the size, extent, connectivity and condition of the Basin’s water resources.
  • Future climate series to drive hydrological models using a similar method used in the CSIRO Murray-Darling Basin Sustainable Yields project. The method scales the historical climate series to reflect a future climate, informed by projections from global climate models in the Intergovernmental Panel on Climate Change, to model runoff and inflows across the entire Basin. The modelling guides the determination of long-term sustainable diversion limits, taking into account risks to the availability of water due to climate change.
  • Climate sequences over the period of implementation of the first Basin Plan to assess the water resource, environmental and socio-economic implications of proposed diversion limits over the period of implementation of the Plan. A range of possible scenarios were proposed to assess system robustness and resilience to historical droughts as well as future climate projections.

For more information download the groundwater fact sheet on page eight.

Read the report CSIRO Climate Report to the Murray-Darling Basin Authority [3.06MB PDF, external link]

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