Water resource development in priority geographic areas

Detailed data for 2004–05 covering water availability, use and management was collated for 51 priority geographic areas as nominated by the states and territories. This data was used for assessing the level of water resource development – key datasets being:

  • volume of water in storage (surface and groundwater)
  • surface water runoff
  • groundwater recharge
  • sustainable yields (surface and groundwater)
  • entitlement volumes (surface and groundwater)
  • surface water diversions
  • groundwater extractions

These data have been collected from a range of sources as part of AWR 2005, including the Level 1 AWR 2005 assessment, the Water Availability Level 2 water balances for priority geographic areas, the Water Use report Water Entitlements, Allocations and Trading , and the Bureau of Rural Science’ Water 2010 (BRS 2006).

The data used for assessing the level of water resource development are detailed in the summary table (Summary water availability use and management data for priority geographic areas, PDF 50.5Kb).

This assessment of the data for 51 priority geographic areas has also identified areas where data did not exist or were not available for this assessment, where the resolution of available data did not facilitate a comparison between parameters, or where different management approaches have meant that certain datasets (for example, sustainable yield) were not available for the 2004–05 year.

Water resource development ratios

Using a single year’s data to assess the level of water resource development is, of course, scientifically incomplete and limited by the climate conditions in that year. Longer time periods—of at least 10 years or more—are needed to more appropriately consider the range of climatic conditions that will affect water resource availability.

For Australian Water Resources Assessment 2000 (NLWRA), Level of Development was determined by comparing entitlements with sustainable yield. It is considered here that this is no longer an appropriate way of assessing level of development, because current water management policies in some jurisdictions are based on seasonal allocations (rather than entitlements), which reflect water availability from year to year.

Consequently, a number of water resource development ratios have been considered for the selected water management areas, to help prioritise activity under the NWI. These ratios provide an overview of the level of water resource development and a baseline against which future changes can be measured, and allow for a preliminary identification of the level of water resource development that existed for the 51 priority geographic areas in 2004–05.

These water resource development ratios allow the following questions to be considered for each priority geographic area:

  • What was the level of water use in 2004–05?
  • What proportion of water management area inflows went to consumptive use in 2004–05?
  • What proportion of the total water resource (inflows plus opening storage) went to consumptive use in 2004–05?
  • What level of stress were our water resources under in 2004–05?

The answers to these questions allow a preliminary assessment of the level of development pressure on the water resource for each water management area.

Description of water resource development ratios

Issue

Ratio

Definition

Level of use

Total diversions and extractions as a proportion of total sustainable yield

(Total surface water diversions plus groundwater extractions) divided by (total combined surface water and groundwater sustainable yield figures for the water management area)

Consumptive use as a proportion of inflows

Total diversions and extractions as a proportion of total inflows

Total inflows comprise surface water runoff, groundwater recharge and transfers into the system.

Consumptive use as a proportion of water resource

Total diversions and extractions as a proportion of total water resource (includes opening storage volumes)

Total water resource comprises total inflows to surface and groundwater in a given year (see above), plus the volume of water in store at the start of the year.

Using the above descriptions and the detailed data collated from the priority geographic areas, it is possible to undertake a preliminary assessment of the level of development and use of the water resource in 2004–05.

It is noted that under 2004–05 water governance arrangements there were differences in the way each state and territory determined their water allocations and sustainable yields. Additional information on some of the limitations due to the varying definitions of entitlements, allocations and sustainable yields is provided for readers.

With respect to results of the comparative analysis using simple water resource use ratios the following points are made:

  • The data used for this assessment provide only a snapshot of 2004–05. Longer temporal assessments (of at least 10 years or more) are required to consider fully the range of risk and reliability figures across a range of wet, dry and average years.
  • Since water allocations are determined based on water availability from year to year, and in the Murray-Darling Basin, on the cap, the volumetric levels of entitlements are largely academic. Water management areas where entitlements are high relative to sustainable yield are indicative of water licensing policies and sustainable yield estimates that probably reflect past wetter climates and previous government policies.
  • The use of actual allocations, or where these are not available, of diversions and extractions, relative to sustainable yield is considered a more preferable measure of the degree of overallocation.
  • It is important to note that CSIRO through the Murray-Darling Basin Sustainable Yields Project is currently undertaking a detailed assessment of water availability in the Murray-Darling Basin under historic, current and potential future climate and development scenarios. AWR 2005, in contrast, shows a retrospective snapshot of what actually happened in 2004–05.

As annual allocations reflect water availability, and may be considerably less than full entitlements in drier years, it is critical to recognise that the water development ratios as presented in the last three columns of the summary water availability use and management data for priority geographic areas, identify those water management areas potentially under the greatest stress from development. It must be emphasised that in practice some states (particularly New South Wales and Victoria) use allocation regimes to restrict the level of use to below the level of entitlements. To address fully the requirements of the NWI, further work will be required to provide a better estimate of the impact of water entitlement and allocation policies on the environment, based on the ratio of the average consumptive pool (representing both the level of entitlements and allocations) and level of use compared to the sustainable yield over an extended time period (of at least 10 years or more).

The 2004–05 diversions / extractions as a percentage of 2004–05 total inflows, and 2004–05 diversions / extractions as a percentage of the 2004–05 total water resource, also provide some insight into the level of development and resulting stress that these water management areas were under in 2004–05.

Given that AWR 2005 is based on data provided by the states and territories for 2004–05 (the first year of the NWI), and considers only one year’s data, the following findings and discussion must be considered as only a preliminary approximation. Nevertheless, fundamental to the NWI is the determination of water management areas that may be under environmental stress because of past and current entitlement and allocations policies and practices.

Level of water resource development

The Level 1 assessment of AWR 2005 reported that of 340 surface water management areas, three (1 per cent) were overallocated, with a further 44 (13 per cent) highly developed. For groundwater management units, 19 (5 per cent) were overallocated and 85 (23 per cent) were highly developed. This was based on self-assessment by each jurisdiction. It was noted that these estimates are significantly lower than that assessed for the previous Australian Water Resources Assessment 2000 (NLWRA), and while in some cases this was due to management changes, in other cases it was a result of changes to definitions of sustainable yield and level of development.

For the AWR 2005 Level 2 assessment of 51 representative water management areas, a nationally consistent set of water resource development ratios has been developed to help identify those areas that are most likely to be stressed (overallocated, fully allocated or approaching full allocation). This is still dependent on the states and territories own respective assessments of sustainable yield. However, the results of the current analysis of the 51 representative water management areas are more consistent with the previous findings of the Australian Water Resources Assessment 2000.

The results from the 51 water management areas considered (based on available data for 2004–05) indicate there were:

  • three water management areas with consumptive use greater than sustainable yield (overused)
  • seventeen water management areas with a high level of consumptive use as a proportion of inflows
  • eleven water management areas with a high level of consumptive use as a proportion of the total water resource.

Two water management areas (Great Artesian Basin and Mereenie Sandstone) appear to have had consumptive use greater than the total annual inflow in 2004–05. In the Mereenie Sandstone there is an acknowledged mining of the resource, with the sustainable yield determined to limit extraction to 80 per cent of total aquifer volume over 320 years.

To assess the different levels of development and use of water resources, the following criteria have been used

 

Category

Criteria

Level of use

Low level of use

Sum of diversions and extractions is less than 30 per cent of sustainable yield

Moderate level of use

Sum of diversions and extractions is between 30 per cent and 70 per cent of sustainable yield

High level of use

Sum of diversions and extractions is between 70 per cent and 100 per cent of sustainable yield

Overused

Sum of diversions and extractions is more than 100 per cent of sustainable yield. See also: Definition: overuse

Consumptive use as a proportion of inflows

Low

Consumptive use is less than 10 per cent of total inflows

Moderate

Consumptive use is between 10 per cent and 30 per cent of total inflows

High

Consumptive use is greater than 30 per cent of total inflows

Consumptive use as a proportion of water resource

Low

Consumptive use is less than 10 per cent of total water resource

Moderate

Consumptive use is between 10 per cent and 30 per cent of total water resource

High

Consumptive use is greater than 30 per cent of total water resource

Level of water resource development for selected water management areas in 2004–05 based on allocation, use and inflows

Water Management Area

Level of Water Resource Development

Level of use

Consumptive use as a proportion of inflows

Consumptive use as a proportion of water resource

New South Wales

 

 

 

Gwydir River – Regulated#

moderate^

high

moderate

Richmond River

low

low

low

Namoi River - Regulated#

high^

high

moderate

Macquarie River - Regulated#

low

high

moderate

Hunter River - Regulated

moderate

high

moderate

Lachlan River - Regulated#

moderate

high

high

Murrumbidgee River - Regulated#

high

high

high

Northern Territory

 

 

 

Daly River

low

low

low

Goyder River

low

low

low

Roper River

low

low

low

Ti Tree

low

moderate

low

Mereenie Sandstone - Alice Water Control District

moderate

high

low

Queensland

 

 

 

Burnett

moderate

moderate

moderate

Pioneer

moderate

moderate

moderate

Condamine-Balonne#

n/a

moderate

moderate

Barron

moderate

moderate

low

Georgina-Diamantina

n/a

low

low

South Australia

  

  

  

Rocky River (Kangaroo Island)

n/a

n/a

n/a

Barossa Prescribed Water Resources Area

moderate

high

high

Lower Limestone Coast Prescribed Well Area

moderate

moderate

moderate

Patawalonga

n/a

high

high

Tasmania

 

 

 

Macquarie

low

high

moderate

South Esk

low

moderate

moderate

Mersey

low

low

low

Pitt Water-Coal

low

moderate

moderate

Victoria

 

 

 

Goulburn River#

high

high

high

Broken River#

high

moderate

low

Ovens River#

low

low

low

Wimmera River#

high

moderate

moderate

Glenelg River

low

moderate

moderate

Moorabool River

moderate

moderate

moderate

Western Australia

 

 

 

Harvey River

moderate

moderate

moderate

Collie River

moderate

moderate

moderate

Carnarvon

high

low

low

Gnangara Mound

overused

high

high

South West Yarragadee

low

low

low

Capital Cities

 

 

 

Adelaide water supply area

overused

high

high

Australian Capital Territory

moderate

moderate

moderate

Brisbane water supply area

moderate

moderate

moderate

Darwin water supply area

moderate

low

low

Hobart water supply area

n/a

low

low

Melbourne water supply area

high

moderate

moderate

Perth water supply area

high

moderate

moderate

Sydney water supply area

n/a

high

high

Interjurisdictional Areas

 

 

 

Border Rivers#

moderate

high

high

Coopers Creek

n/a

low

low

Great Artesian Basin

overused

high

high

Lake Eyre Basin~

high

moderate

moderate

Murray Darling Basin#

high

high

high

Ord River

low

low

low

Snowy River

high

low

low

Data sourced from Summary water availability use and management data for priority geographic areas.
Level of Water Resource Development categories are defined in the previous table.
# These areas fall within the Murray-Darling Basin and will be assessed in greater detail by the CSIRO in 2007 to quantify current and future water availability.
^ Total Sustainable Yield for the Gwydir and Namoi Rivers (Regulated) do not include Rainfall/Runoff Harvesting Usage, therefore this calculation is based on the Total Diversion/Extractions less the Rainfall/Runoff Harvesting Usage.
n/a: Not assessed or data not available.
~ The high groundwater extraction figure in the Lake Eyre Basin (LEB) is due to the overlap of the LEB with the Great Artesian Basin (GAB). GAB is an integral part of the LEB, due both to the important spring ecosystems and because it supplies the vast majority of the groundwater used in the LEB. Refer to the AWR 2005 Water Availability report where detailed water balances are provided.

 

Levels of consumptive use compared to inflows across Australia in 2004-05

Levels of consumptive use compared to inflows across Australia in 2004-05

Notes:

  • The Gnangara Mound groundwater management area underlies the Perth Water supply Area, but is illustrated in this map due to it high consumptive use category. The Perth Water Supply Area has moderate water use.
  • The Great Artesian Basin (GAB) underlies large areas of the Lake Eyre Basin, Georgina-Diamantina, Cooper Creek and the Murray-Darling Basin surface water management areas and therefore is not clearly shown, except for in its northern and south-western portions. The GAB rates high in the consumptive use category.

It must be emphasised that as these assessments are based on only one year’s data, they can be considered only as a starting point against which future change and trends can be assessed. These results, therefore, are potentially indicative of the most highly developed or utilised systems. Longer periods of measurement and assessment are required to determine the degree of environmental stress and its impact on identified environmental assets.

It was not possible to assess some areas because sustainable yield data were not available. In some cases, the absence of sustainable yield data does not indicate a lack of a management, as alternate approaches may be used in the pursuit of sustainable outcomes. For example, some areas of Queensland, as well as the Great Artesian Basin, have sustainability goals set around the maintenance of water flows, or groundwater pressures, rather than the identification of a sustainable yield volume.

It is clear from the current work on level of water resource development that there is a need for improved and consistent methodologies for determination of water availability that take in recent climate trends and longer time sequences. The Murray-Darling Basin Sustainable Yields Project being conducted by CSIRO is doing this for all catchments in the Murray-Darling Basin, but there is a major need for all highly developed water management areas elsewhere to be investigated in a similar manner.

Key observations

  • The water balance approach has limitations when being used to quantify the extent and nature of surface water – groundwater interactions. A biophysical assessment approach, with regard for the processes occurring in key areas of the water management area, is recommended to better identify and quantify the interaction.
  • This study concludes that there are concerns with the use of the term overallocation as defined in the NWI and suggests that consideration be given to a new term, ‘over-entitlement’, that would be synonymous to the National Land and Water Audit’s term ‘over-development’.
  • Data for environmentally sustainable levels of extraction and sustainable yields used in this study were provided by the states and territories. Given that they are important in the calculation under the NWI of overallocation and overuse, there is concern that they are determined differently from jurisdiction to jurisdiction and that they may not reflect the impact on water availability of the past ten years of climate variability, climate change and land use trends.

Related links

The overallocation and overuse of water are discussed in more detail in the following section:

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This website was last updated in 2007. It is no longer being maintained but remains here as an archive for information.11/09/2007