Murray-Darling Basin Commission C Salinity Update 2003 Salinity

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					                                                Murray-Darling Basin Commission – Salinity Update 2003

                                                                   Salinity Levels in the River Murray

Salinity Levels – 1980 to 2003

One of the clear successes of the Murray-Darling Basin Salinity and Drainage
Strategy 1988-2001 has been the coordinated efforts of community groups
and Governments to control and reduce salinity levels in the lower parts of the
River Murray, and this success has been widely recognised in recent years
(MDBC 1999, MDBMC 1999, 2001).

The improvement in long-term average salinity levels in the River Murray at
Morgan since 1980 is shown below. This improvement in salinity levels has
been in response to significant investment by Governments in dilution flows,
building and operating salt interception schemes, and due to the effectiveness
of State salinity action plans and Land and Water Management Plans.

                                                        The Effect of Salinity Management in the Murray-Darling Basin -
                                                     Average Salinity Levels in the River Murray at Morgan (South Australia)
                                               900

                                                                                            "Without Intervention" Salinity Levels
                                               800
(Five Year Moving Average - EC uS/cm)




                                               700
    River Murray Salinity at Morgan




                                                     Construction of first
                                               600   Salt Interception Scheme


                                               500

                                                                                Recorded Salinity Levels
                                               400

                                                                                                             Effect of Salinity Management (~200EC)
                                               300


                                               200


                                               100


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The major salt interception schemes constructed in the Murray-Darling Basin
since 1980 and their estimated effect in reducing average river salinity are
shown in the following table:

                                                        Salt Interception Schemes                                                Date            Salt Credits
                                                                                                                                                    EC at
                                                                                                                                                  Morgan
Mildura-Merbein and Buronga Salt Interception Scheme                                                                             1981              33 EC
Noora Drainage Diversion Scheme                                                                                                  1982              21 EC
Rufus River Salt Interception Scheme                                                                                             1984              43 EC
Additional Dilution Flows                                                                                                        1986              28 EC
Upgraded Mildura Merbein and Buronga SIS                                                                                         1991               3 EC
Woolpunda Salt Interception Scheme                                                                                  1992                 41 EC
Waikerie Salt Interception Scheme                                                                                   1992                 13 EC
Mallee Cliffs Salt Interception Scheme                                                                              1994                 13 EC
Psyche Bend Drainage Diversion Scheme                                                                               1996                  1 EC
Barr Creek Drainage Diversion Scheme -New Rules                                                                     1999                  6 EC
TOTAL EFFECT                                                                                                                            ~200 EC

Salinity Levels – 2002 to 2003

Salinity levels in the River Murray during last year’s drought are shown in the
figure below, along with the estimated salinity levels if the above salinity
management actions were not in place. These recoded salinity levels were
lower than the long term average as a result of several factors including the
source of the water, South Australia receiving full entitlement flow and the
reduction in saline inflows due to the drought.

As a result of low inflows and low water levels in Menindee Lakes and Lake
Victoria during the 2002/2003 season, the majority of flows along the River
Murray were sourced from Dartmouth Dam, which holds some of the freshest
water in the River Murray system. In addition South Australia received full
entitlement flow of 1850 GL, thus ensuring adequate dilution of saline
groundwater inputs.

This situation was in contrast to other drought periods such as 1982/1983
where flows were sourced from more saline storages including Menindee
Lakes and Lake Victoria, and 1967/1968 when South Australia experienced a
reduction in its entitlement flows due to low resource availability.

In addition to these factors the dry conditions across the Basin in 2002/2003
contributed to a reduction below average levels for saline inputs from
groundwater and irrigation return flows.

                                                       The Effect of Salinity Management in the Murray-Darling Basin
                                                                Daily Salinity Levels - Jan 2002 to July 2003
                                     1200
                                            Australian Drinking Water                            "Without Intervention" Salinity levels
                                            Guideline Limit (800 EC)                       (No Salt Interception Schemes and Dilution Flows)
                                     1000
   River Murray Salinity at Morgan
      (Daily Salinity - EC uS/cm)




                                     800




                                     600


                                                     Recorded Salinity Levels
                                     400




                                     200

                                                                                       Effect of Salinity Management (~ 70 to 270 EC)

                                       0
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                                                                                    Date
While South Australia received full entitlement flow in 2002/2003, without
good rainfall throughout the catchment and an increase in resource availability
for 2003/2004, flows may be cut and this would be expected to result in
increased salinity levels along lower reaches of the River Murray over coming
months.


Future Salinity Risks – Dryland Salinity

While the successes of the 1988 Salinity and Drainage Strategy have
provided some breathing space, recent efforts to assess future Dryland
Salinity Risk have emphasised that ongoing efforts to manage salinity are
essential.

The Salinity Audit of the Murray-Darling Basin (MDBMC 1999) estimated
future salt loads to the streams and rivers in the Basin over the next 100
years. This assessment showed that salt, previously stored in the landscape,
is being mobilised by long term rises in groundwater tables due to land use
changes across the Murray-Darling Basin.

The Salinity Audit estimated that ‘Business as usual’ would mean that the
reduction in lower River Murray salinity achieved over the last decade would
be cancelled out within 20–30 years, and median salinity levels would exceed
the Australian Drinking Water Guideline for good quality water within 50-100
years.

Following on from the work of the Salinity Audit, the Australian Dryland
Salinity Assessment (NLWRA 2000) undertook additional work to estimate the
area at risk and the impact of Australia’s dryland salinity over the next 50
years.

The Australian Dryland Salinity Assessment estimated that the area with a
high potential to develop dryland salinity in Australia would increase from 5.6
million hectares in 2000 to 17.0 million hectares in 2050. Within the Murray-
Darling Basin it was estimated that about 3.4 million hectares of land in the
eastern and southern regions of the Murray-Darling Basin will be at risk by
2050, as shown in the table and figure below.

Areas (hectares) with high potential to develop dryland salinity in Murray-Darling Basin

         State                       1998/2000                        2050
New South Wales                      150,500 Ha                   1,300,800 Ha
Victoria                             445,400 Ha                   1,444,500 Ha
Queensland                           48,000 Ha                     628,400 Ha
South Australia                      19,800 Ha                     34,000 Ha
TOTAL                                663,700 Ha                   3,407,700 Ha
(Source - NLWRA 2000)
Land with high potential to develop dryland salinity in Murray-Darling Basin (2050)




Given the estimated future dryland salinity risk within the Basin, any
complacency in ongoing efforts to manage salinity is clearly unacceptable.

Current and Future Management of Salinity

The National Action Plan for Salinity and Water Quality (NAP) was endorsed
by the Council of Australian Governments on 3 November 2000. It is a seven-
year national framework that targets salinity and water quality protection with
the joint resources of the Commonwealth and State and Territory
governments backed by an over-arching Inter-governmental Agreement. The
NAP targets nine priority regions in the Murray-Darling Basin for addressing
salinity and water quality issues.

The Basin Salinity Management Strategy (2001-2015) was prepared with
substantial input from all six of the governments within the Basin, the
Community Advisory Committee and technical experts, and was approved by
the Murray-Darling Basin Ministerial Council in September 2001.
The Basin Salinity Management Strategy guides communities and
governments in working together to control salinity and protect key natural
resource values within their catchments. It establishes targets for the river
salinity of each tributary valley and the Murray-Darling system itself, which
reflect the shared responsibility for action both between valley communities
and between States.

The Strategy provides the framework for salinity management in the Basin for
the next decade, and has the following objectives:

      -   Maintain the water quality of the shared water resources of the
          Murray and Darling Rivers for all beneficial uses – river salinity at
          Morgan, S.A., will be maintained at less than 800 EC for 95% of the
          time;
      -   Control the rise in salt loads in all tributary rivers of the Murray-
          Darling Basin, and through that control, protect their water
          resources and aquatic ecosystems at agreed levels – meeting the
          end of valley salinity targets;
      -   Control land degradation and protect important terrestrial
          ecosystems, productive farm land, cultural heritage, and built
          infrastructure at agreed levels Basin-wide – expressed as “within
          valley targets”; and
      -   Maximise net benefits from salinity control across the Basin.


References:

Murray-Darling Basin Ministerial Council (1988). Murray-Darling Basin
Salinity and Drainage Strategy.
Murray Darling Basin Commission (1999). Salinity and Drainage Strategy –
Ten Years On 1999.
Murray-Darling Basin Ministerial Council (1999). The Salinity Audit of the
Murray-Darling Basin. A 100-year perspective, 1999.
Murray-Darling Basin Ministerial Council (2001). Basin Salinity Management
Strategy 2001-2015.
National Land and Water Resources Assessment (2000). Australian Dryland
Salinity Assessment 2000.

Further Information:

Phone: 02 6279 0100
Web: www.mdbc.gov.au
Email: salinity.project@mdbc.gov.au

				
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posted:11/16/2011
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