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Water use in the Murray Darling Basin
This material addresses aspects of the following syllabus outcome:
H5.1 evaluates the impact of innovation, ethics and current issues on Australian agricultural systems
H3.4 evaluates the management of the processes in agricultural systems
(Source: NSW Board of Studies Agriculture Stage 6 syllabus p 20)
In this activity you will critically analyse the use of water for irrigation systems used along some of the farms in the Murray Darling Basin (MDB) and consider what options there are available to farmers to decrease their water consumption and to improve efficiency of water use.
Introduction
The Murray Darling Basin (MDB) is Australia’s most important Agricultural region, with over 41% of the nation’s gross value of agricultural production coming from this region. The MDB is the largest area of irrigated agriculture in Australia and has been termed Australia’s agricultural ‘heartland’, its ‘food basket’. Expansion of agricultural developments has been made possible through the use of water from the Murray Darling River system. The agricultural output from this area makes a major contribution to the national economy, with the potential in the future to make a substantial contribution to Australia’s food exports, provided that this is undertaken in a way that is consistent with sustainable land management.
The debate over the fate of the MDB is at the forefront of environmental, agricultural and political news. With Australia’s worsening water crisis having a huge impact on agriculture, especially in this part of the country.
Assessment and study of the crisis occurring in the MDB is essential in understanding the environmental, economic, ethical and political issues facing Australian agriculture today.
In 1992, the governments and communities that share the Murray Darling Basin formed a partnership and came up with a purpose:
'to promote and co-ordinate effective planning and management for the equitable, efficient and sustainable use of the water, land and other environmental resources of the Murray-Darling Basin'. (http://www.mdbc.gov.au/about/murraydarling_basin_initiative__overview 
)
This Initiative is the largest integrated catchment management program in the world, covering the watersheds of the Murray and Darling rivers, an area of over one million square kilometres. This agreement recognised the fact that no one government or community was able to confront the issues of the emerging natural resource management problems on their own or in isolation.
For this activity you will explore the available information on water allocations in the MDB. Go to the following website and read the information. When you have understood what the water allocations are about choose ‘The Cap Brochure’ from the list of links on the right hand side of the page. Click on this brochure to download (http://www.mdbc.gov.au/nrm/the_cap ).
Read this brochure and answer the following questions:
- Explain the factors that contribute to the need for a ‘cap’ on water allocations to irrigators.
- Why is an audit of water use a necessity?
- What type of monitoring is carried out on the Cap system?
- How well has implementation of the Capmet the expected results and what type of changes need to be addressed?
- What are the two main reforms that have been promoted through the Cap?
ACTIVITY 2
Using the information in the table below make a graph to show the water requirements of some crops grown in MDB:
The answer link provided below is an Excel spreadsheet.
| CROP | AVERAGE IRRIGATION REQUIEMENTS (MEGALITRES/HA) |
|---|---|
| Rice | 12.1 |
| Lucerne for hay | 10 |
| Corn | 8 |
| Asparagus | 8 |
| Watermelon | 8 |
| Tomatoes | 8 |
| maize | 7.15 |
| Cotton | 6.7 |
| Soybeans | 6 |
| Sugar cane | 5.4 |
| Pasture for grazing | 4 |
In recent years much of the blame for over use and inefficient use of irrigated water has landed on the shoulders of the cotton farmers.
To gain an understanding of the water use on a cotton farm you will look at the cotton industry and assess the sustainability of this enterprise. You can do this by completing the work in Cotton farming in Australia.
The MDB also supports the growing of vegetable crops, orchards and fruits. Water is generally used more efficiently in the production of these crops than in the production of cotton.
Investigate the methods of irrigation used in the production of vegetable crops, orchards and fruits in the MDB in Best practice for growing vegetables.
CONCLUSION
The health of our river systems is essential for a healthy environment and a productive, sustainable agriculture industry. The introduction of water reform regulations is an attempt to encourage the recognition of the importance of environmental flows which will then restore the ecological processes necessary for healthy river systems.
The agriculture sector must compete for use of water with other industries, domestic use, environmental flows and recreational use. Water supplies in Australia are limited and efficient use of allocations is essential for the sustainability of horticulture industries into the future.
The whole of catchment approach to water management ensures that over irrigation and poor management of drainage water are managed by all and will help to prevent the loss of previously productive land to raised water tables and the associated salinisation of soils.
If farmers can maintain well planned and managed irrigation and drainage systems then there will be less run-off above natural levels and only small losses to the water table. Farmers need to aim for minimum discharges of salt, fertiliser, pesticides and organic matter into the river system. In agriculture, we must consider all aspects of water management at the initial design stage – this includes system design, irrigation scheduling, water quality, fertigation options, and drainage management.
The choice of irrigation systems by farmers is dependent on their knowledge of the crops they are growing and the soil on their farms. Irrigation scheduling is the most efficient way that farmers can deliver the right amount of water at the right time.
The method of delivery is important in an irrigation system. The main methods include: furrow irrigation, overhead irrigation, drip and trickle systems and low-pressure under tree systems. Irrigation efficiency increases with increasing precision of water delivery. For example, flood or furrow irrigation and high pressure, high volume sprinkler systems are generally the least efficient. The most efficient are micro sprinklers or dripper systems which target the root zone of the crop.
The NSW government is investing in education strategies to help irrigators develop land and water management plans which aim to increase efficiency and minimise off-farm impacts of irrigated horticulture. The water crisis is causing an increase in the cost of water as well as the availability of it and this will continue to drive the move towards more efficient irrigation systems.
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