Science providing a sound basis for water decisions

Australia is in the most intense and ambitious period of water reform in our history, in the middle of a prolonged and painful drought and grappling with the prospect of a drier future. It is to our great credit that this reform is increasingly underpinned with scientific evidence.

The most prominent example of science engaging with our water challenge is the recent Murray–Darling Basin Sustainable Yields Project (MDBSY), arising from the emergency Water Summit on 6 November 2006, where the Prime Minister and the premiers of Queensland, NSW, Victoria and South Australia called upon CSIRO to report on the water resources of the ailing basin.

In a world first for rigorous and detailed basin-scale assessment, a single project brought together skills from across Australia to investigate the current and future availability of surface and groundwater resources of the Murray–Darling Basin (MDB), covering one-seventh or our continent. It also represents the most comprehensive hydrologic modelling ever undertaken for the entire MDB.

The ensuing project, led by CSIRO’s Water for a Healthy Country Flagship, has been the largest single undertaking in CSIRO history. It involved contributions from more than 150 scientists and technicians from 12 organisations, including state water departments and the Murray–Darling Basin Commission (MDBC), supported by the National Water Commission.

From the start, success for this undertaking would be the broad acceptance that these estimates of water resources were the best possible with our current science and data. Reports for all 18 regions of the MDB have now been presented to government and key stakeholders, and have been met with widespread acceptance and appreciation.

In aggregate these reports paint for the first time a comprehensive, quantitative picture of an immensely complex system, how it has changed with development, and how it may change into the future.

The project involved linking more than 70 different surface and groundwater models of surface and groundwater flows and extractions within the basin’s 18 individual regions. Data that originated from state departments and the MDBC was utilised, creating a data archive of 60 terabytes. Historical daily climate data from 1895 to 2006 for five-kilometre-by five-kilometre grids across the basin were used to develop the integrated picture.

The work dynamically links groundwater balances with surface water availability, calculating flows through and between the system’s rivers, and groundwater/surface water interactions under current water-sharing arrangements, before estimating the water available under each future scenario.

The development of this integrated hydrological model of the entire basin means water-management agencies can now assess the potential consequences of their management policies and decisions under dry, moderate or wet future climatic scenarios, at the level of each catchment, or across the entire basin.

We are making huge strides in the deliberate and comprehensive application of our best science and technology to inform decisions about how much water there is to share and accelerate resolution of the challenging issue of how water resources should be shared.

The new Murray–Darling Basin Authority now has a more complete and agreed platform on which to base its planning, including the new sustainable diversion limit.

The value and confidence in this science is reflected in the subsequent call by the Council of Australian Governments (COAG) for CSIRO to provide a comprehensive scientific assessment of water yield in all major water systems across the country, to allow a consistent analytical framework for water policy decisions across the nation.

Regions now being studied as a part of this expansion are northern Australia, south-west Western Australia and Tasmania.

More information:

About the projects

Murray-Darling Basin Sustainable Yields Project reports

Water for a Healthy Country Flagship

Dr Tom Hatton is Director of CSIRO’s Water for a Healthy Country Flagship and is responsible for the management and delivery of science to address one of Australia’s biggest challenges – the sustainable management of our water resources. He provides science leadership to a team of more than 500 leading research scientists and technical staff with skills in areas as diverse as hydrology, ecohydrology, sociciology, information and communication technology, atmospheric research, environmental management, economics and biology. Prior to this appointment Dr Hatton was Deputy Chief of CSIRO’s Land and Water Division. He joined CSIRO in 1988, following a postdoctoral position in mathematics with the University of New South Wales.

Editor's Note: This article was first published in Australian Academy of Technological Sciences and Engineering's (ATSE) Focus Magazine issue 153 (River Health and Water). This article is under copyright; permission must be sought from ATSE to reproduce it.