Essay: The Murray-Darling drainage basin

The Murray-Darling drainage basin is located in the South-East of Australia and drains ~ one-seventh of Australia’s land mass. It has an area of 1,061,469 km^2 and is ~ 3,375 km long in length. Within the basin there are three main rivers which are the Murray river (2,508 km long and Australia’s longest river), the Darling river (1,474 km long) and the Murrumbidgee (1,690 km). In general the basin is flat, at a low elevation and is is mostly located far inland. The basin receives little direct rainfall (average of 471mm per year) with the North-eastern section (subtropics so more humid) receiving more rain fall (up to 1,500mm annually) than the semi-arid and arid South-western side (less than 300mm annually). As the rivers within the

Fig.1 A map showing the Murray-Darling Basin Murray-Darling are largely flat and have mainly low gradients over their course, the rivers tend to be slow flowing and meander often.

In terms of importance, the basin is one of the most important agricultural areas in the country containing 40% of all Australian farms and producing ~ one-third of the nation’s food supply. Crops produced here also make up ~ one-third total gross value of agricultural production. This area produces crops like cotton, rice, wheat, many varieties of fruits and vegetables as well as dairy products, sheep, cattle etc.  While the basin is therefore of economic importance it is also important because of its cultural heritage due to the strong connection Australia’s aboriginal people have with it. For example there are just under 50 Aboriginal Nations whose traditional lands lie within the basin and the rivers and land within the basin are central to the aboriginal people’s cultural beliefs and practices. There is also an estimated population of 2 million people living within the basin (which includes the capital city Canberra). The basin also has significant levels of biodiversity with 80 species of mammals (of which ~60 extinct though), 55 species of frogs, 46 species of snakes and 34 species of fish (e.g. Golden Perch). Of these native animals 10 species of mammals, 18 of frogs, 5 of snakes and up to half of fish species are endangered making the basin and important place to protect.  Obviously the Basin is most important for its supply of water, a resource for which there is much conflict between three main stakeholders which are the industry sector, the agricultural sector and the domestic sector (which includes recreational use of water).

Competing demands for water

One of the main sectors that competes for highly demanded water in the Murray-Daring Basin is the large (see above) agricultural industry within the basin. In particular farmers require the largest amount of water to use for irrigation to water crops and create the optimum conditions to maximise crop yield and so to maximise food production and profits. For irrigation, (the largest user of water in the drainage basin) ~ 3,780 GL is annually diverted from rivers in order to irrigate ~ 470,000 hectares. This is overseen by the MDBA (Murray Darling Basin Authority) who controls the proportion of water each state (South Australia, New South Wales, Victoria and Queensland is allocated every irrigation season. Within states like NSW, there is an allocation system determine the proportion of water to be used for irrigation on each from (from the state’s MDBA allowance) based on farm area. however since 1975 there has been a ban on the issuing of new water entitlements for irrigation so from 1983 farms began transferring water entitlements between the,selves to increase / decrease water usage in some areas. The amount of water required by farms depends on the type of crop being produced as some are more water intensive than others. For example rice production (Australia’s 9th largest agricultural export with 1.2million tonnes grown per year) uses up 1550 litres for every kg produced rather than for example maize which only uses 540-630 litres for each kg produced. This is particularly relevant as 100% of Australia’s rice production takes place within the basin. The Murray Darling’s largest agricultural use of water is for cotton production though which in 2008 used up 20% of all water used for agricultural production in the basin (rice used 16%). The amount of water used by each crop in comparison to the money made from producing each crop (more money increases the importance of water use to grow crop) is shown by the diagram below taken from ‘The Weekend Australian’ in 2001:

Fig.2 A diagram comparing the water needed by each crop to the profit made from its production.

There is also a large demand for water from the Murray Darling Basin to be used for domestic and industrial purposes (200 GL per year and 52% of Australia’s total water consumption in 2004) ) in particular in urban areas like Adelaide which receives 55% of its water supply from this drainage basin. The estimated 200 GL per year of water is diverted from the basin into South Australia’s pipeline network which takes water to urban ares like Adelaide and industry hotspots like the ‘Iron triangle’, which is the iron-producing region between the towns of Port Augusta, Port Pirie and Whyalla. In fact 90% of the water used in Iron production in this area is supplied by the Murray-Darling. Water demand in industry (9% work in manufacturing industry) is high as large and profitable sectors in Southern Australis like Steel and Iron production require large quantities of water such as too cool down machinery and in the case of iron production to cool down coke.

In terms of domestic use it is estimated that almost 4 million people in South Wales, mainly in urban areas like Adelaide and Canberra rely or partly rely on water for the Murray Darling basin for domestic use. The 4 million people need water for everyday domestic purposes including drinking, cooking food, washing clothes, showering etc and is essential to maintain high standards of living / quality of live and to Australia’s high level of development as domestic water use improves levels of health and sanitation which increase productivity. Households themselves accounted for 2% of water consumed int the basin (2004) Water for recreational use is also important in southern Australia and for this to be possible water levels on the rivers in the Murray Darling Basin cannot decrease by too much. Recreation in the form of fishing, swimming, kayaking and hiking are common throughout the basin and in some areas to an extent that tourism has developed across the basin making billions of dollars for the economy. Recreation and tourism are particularly popular at Ramsar wetlands e.g. Corona National Park, the Willandra Lakes region etc and therefore there are conflicts betweens those who want to protects are parts of the basin for recreation / tourism (e.g. by setting up national parks /reserves) and those who prioritise for example increased usage for irrigation rather than conservation. it is also worth noting that conflicts do also exist between the aboriginal people who want to protect their land (in the basin) from exploitation and other stakeholders as Aboriginal people view water from Murray-Darling rivers as part of their culture and identity. They use the water in many of their everyday practices such as for ancient burial sites, ancient fishways as a source of food e.g.  below the weir at Brewarrina etc.

Strategies adopted to meet competing demands:

In 1918 the Federal Government formed the Murray River Commission, which is now the Murray-Darling Basin authority, tasked with managing the water in the basin to meet the competing demands for water from the Murray-Darling Basin. As part of the 1915 Murray-Darling Basin agreement the MDBA is in charge of fairly distributing basin water between the different states who then choose how their state uses their allocated water. They also oversaw the construction of storages e.g. Lake Victoria and Hume Reservoir, locks and weirs to protect irrigators and domestic / industrial water security in times of droughts. While they have been successful in protecting demand for irrigation, domestic use and industrial use, it has not met the environment demand as now only 36% of the Murray’s natural flow reaches its mouth (via Lake Alexandria) showing at this early time the immediate demands of people were prioritised over a more sustainable solution. As of 1970 the MDBA was also tasked with reducing river salinity throughout the Murray-Darling Basin (using dilution flows) as increased salinity reduced the quality of water and the efficiency / usefulness of water for irrigation and domestic purposes. E.g. At Torrumbarry and Euston Weirs the MDBA provides a dilution flow which however has had the negative consequence of reducing some water resources.

By 2012 the MDBA, with legislation from the federal government of Australia had redrafted the Murray Darling Basin Plan (to be fully implemented in 2019) to sustainably manage the Basin’s water resources for the future. The aims of this plan are to cut existing water allocations, increase environmental flows and to restrict the total amount of water that could be taken from the basin. The plan also aimed to achieve these while at the same time minimising economic and social impacts. The thinking was that increasing the overall health of the basin and therefore water quality (through this plan) would benefit all stakeholders demanding water: the economy / agriculture sector (as increased quality maximises crop yield and profits) and the environment / community (by reducing water taken from river to be allocated habitats in the basin are protected increasing biodiversity and also recreational opportunities. The limits to be imposed are sustainable diversion limits (SDLs) that cap the amount of water for consumptive use (industrial, agricultural and domestic use) but aim to strike a balance between the water demands of the environment and that of industry / communities. The MDBA calculated that the average environmentally sustainable level of surface water diverted is 10,873 GL per year and so each year 2,750 GL of water would have to be recovered (based on the 2009 baseline diversion level. The plan has already partially come into action with the government already purchasing water entitlements / exchanging them in return for investment in order to recover water. Part of the Plan includes the ‘Water for the future’ scheme where the government is providing $9billion dollars (up until 2019) to improve efficiency of irrigations networks / reducing wastage of water, to reallocate water and to improve water infrastructure of farms (again to increase efficiency).