Introduction

This Atlas presents an overview of data collected up to March 2003 by the Basin Irrigation and Salinity Mapping (BISM) Working Group (formerly IIGIS Working Group) of the Murray-Darling Basin Commission (MDBC). This data has been collected to assist the MDBC and its Partner Governments (South Australia, Victoria, New South Wales, Queensland, ACT and the Commonwealth) to manage salinity issues associated with irrigated agriculture in the Basin.

 

Salinity Management in the Murray-Darling Basin

River Murray salinity has been significantly reduced through implementation of the 1989 Salinity & Drainage Strategy (S&DS), and this has been achieved while undertaking the rehabilitation of degraded lands and allowing for new irrigation development. This was made possible by limiting the amount of salt entering the river through construction of salt interception schemes, and due to the effectiveness of State salinity action plans and Land and Water Management Plans. The indicative target of keeping river salinity at Morgan, South Australia, below the 800 EC threshold at least 95 per cent of the time is close to being met.

The 1999 Basin Salinity Audit has shown that salt, previously stored in the landscape, is now being mobilised on a massive scale by rising groundwater tables due to land use changes across the Murray-Darling Basin. ‘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.

Average river salinities in key tributary rivers will rise significantly, endangering their use for irrigation and urban purposes within 20-50 years, and about 3.4 million hectares of land in the eastern and southern regions of the Basin will be salt affected within 50 years. Although environmental implications are not well understood, river salinity levels are having serious impacts on floodplain wetlands of national and international importance. The current impact costs of dryland salinity in eight tributary valleys of the Basin are estimated to be $247 million per year. The impact costs of salinity to consumptive users of River Murray water total $47 million per year.

The Murray-Darling Basin is the food-bowl of the nation and is a major contributor to Australia’s important and burgeoning food export markets. The Basin is home to unique and environmentally significant natural features, many of which are subject to international treaties. Over two million people directly depend on the natural resources of the Basin for their livelihood, and their future prosperity is dependent upon its sustainable management. These values are at risk from salinity.

The Murray-Darling Ministerial Council’s response to salinity management for 2001-2015 is the Basin Salinity Management Strategy (BSMS). The BSMS has a Basin-wide focus, and will:

The means of achieving these objectives will be the application of targets for the shared water resources (less than 800 EC for 95% of the time at Morgan), for each tributary valley (end of valley salinity, salt load and flow) and for other Basin-wide values and assets (State within-valley management targets).

Baseline Conditions for Salinity Mangement

During the development of the S&DS (and subsequently the BSMS) the Partner Governments agreed to be accountable for all future actions that have a significant salinity effect in the River Murray (> 0.1 EC at Morgan). To support these accountability arrangements, the Partner Governments agreed to draw a line in the sand or "Baseline Date" against which future management would be judged. The baseline date adopted for the Salinity Accountability is 1 January 1988 for New South Wales, South Australia and Victoria and 1 January 2000 for Queensland.

The impact of future actions on River Murray salinity and the associated costs to water users is quantified by evaluating the action against an agreed benchmark climatic sequence (1 May1975 to 30 April 2000), assuming that all actions and commitments prior to 1 January 1988 are in place. The following are included in the definition of Baseline conditions:

Credits are earned for those actions which reduce salinity cost effects at Morgan compared to the baseline conditions, while debits are allocated for those actions which increase costs. These actions and the associated salinity credits/debits for each State are recorded on the MDBC Salinity Register.

Development of the Irrigation Infrastructure GIS

In 1991 the MDBC's Salinity Working Group decided that collection and storage of drainage information on Geographical Information Systems (GIS) would assist with the implementation of the S&DS. Key information was identified to include drain location and date of construction, with additional information collected if necessary including area drained, depth of drain, and location and type of point source salt loads.

After a few years of ad-hoc data collection, an interstate Working Group was proposed to establish common standards for data collection across state borders. State and Commonwealth representatives met with MDBC Office staff, to determine a standard for data being collected. As a result of this process, the Basin Irrigation and Salinity Mapping Working Group (BISM - formerly know as the Irrigation Infrastructure GIS) was established in 1994.

The terms of reference for the BISM Working Group are as follows:

The MDBC Salinity Working Group identified the following data sets for collection under the management of the BISM Working Group:

Pilot projects were established to determine the feasibility of the collection of the identified data sets and to start developing a standard for the storage of the information in GIS. Details such as the attributes that are collected for each data set were determined, the item definitions for storage and the coding options. This information has been continually refined and is represented by the BISM standard.

The pilot projects were successful and the States gained approval from the MDBC to continue collecting information for the rest of the Murray-Darling Basin. The Commonwealth was contracted to develop a database for evaporation basins, which are an integral part of the drainage system for irrigation areas. Over the following years the MDBC has agreed to continue funding the collection of irrigation and salinity management information, with the BISM Working Group coordinating activities and refining the standard as required.

In recent times the emphasis of irrigation related salinity management has changed, in particular due to the increasing effects of new irrigation development associated with water trade. In January 2001 the Salinity Working Group endorsed a proposal to undertake the following activities, thus confirming the reliability of the data and expanding the scope of the BISM Project to enable better assessment of salinity contributions from irrigated areas:

BISM Standard

The standard was initially developed for the key data sets identified by the Salinity Working Group (see Attachment A). There is no national standard that captures the content of BISM Project. It has since expanded for the purposes of incorporating extensive information that was already being collected, and to provide a quasi asset management system.

The format for storage, code values, and protocols if there is no information for a feature, are all incorporated in the standard. The table definitions recommend how the data should be held, which ultimately enables data sets from different sources to be incorporated into one basin-wide data set.

The standard includes the following data sets, with a current order of priority as follows:

  1. Irrigated land use (actual irrigated area, crop type, water right, water usage)
  2. Drainage, supply and salt interception channels
  3. Drainage catchments
  4. Channel structures (groundwater pump type)
  5. Channel structures (other than groundwater pump type)
  6. Water flow and quality gauging stations
  7. Irrigation areas/districts/trusts
  8. Evaporation basins
  9. Gauging station programs
  10. Surface catchments (optional)
  11. Levees (optional)

Information recorded includes year of construction, type of material, source of information, collection scale and management authority. Optional items include condition and capacity of channels.

BISM ATLAS

In May 2001 the Salinity Working Group agreed to the development of an Atlas of the first BISM data to detail and better communicate the nature of the data being collected by the BISM Working Group. The target audience of the Atlas in the first instance is the Salinity Working Group, Partner Governments and other relevant MDBC working groups. The Atlas can be made available to other interested parties, subject to agreement of the data providers.

This BISM Atlas includes data collected up to March 2003. Data collection is ongoing and it is intended that the Atlas will be updated at appropriate intervals to detail and communicate data to relevant stakeholders. Any comments on the content or format of data presented in the Atlas would be appreciated and can be provided on the enclosed feedback form. For further information on the BISM Project please contact:

Murray Darling Basin Commission:

Salinity:
Matt Kendall
(02) 6279 0132
GIS:
Paul Nanninga
(02) 6279 0124

 

State/Commonwealth - See Attachment B (page B1)