From the expansion of cotton, to the emergence of nut plantations and the fluctuating fortunes of rice – the use of irrigation water in the Murrumbidgee catchment has been changing.
Graham Centre researchers have been examining the data.
Read more about the work by Dr Sosheel Godfrey, Dr Tom Nordblom, Dr Ryan Ip and Dr Muhuddin Anwar from Charles Sturt University and Dr Karl Behrendt who is now based at Harper Adams University in the United Kingdom.
The Murray-Darling Basin (MDB) encompasses 22 water catchments. This study focusses on the recent history of water use for irrigation in the Murrumbidgee catchment.
The Murrumbidgee catchment accounts for 8 per cent of the MDB and covers 8.4 million hectares (84,000 square kilometres) of southern New South Wales. Agriculture in the Murrumbidgee valley is quite diverse. Dryland grazing and cereal-based cropping are dominant, accounting for more than 75 per cent of land use. In comparison, only five per cent of the land is irrigated (Murray-Darling Basin Authority, 2020). However, the latter makes a substantial (AUD $1.1 Billion in 2018) contribution to the catchment’s gross dollar value of agricultural production (Figure 1) (Gupta et al., 2020).
Figure 1: Southern NSW Murrumbidgee catchment 2006 to 2018 gross value of irrigated agricultural production (GVIAP) in nominal dollars (millions) for different crops
The irrigated annual and perennial crops planted in the catchment adjust to market forces that result in the shifts in water and land uses over time. Water availability in the southern Murray-Darling Basin is strongly influenced by rainfall in the upper catchments, which varies significantly between years. Allocations of available water among crops (Figure 2) are decided by individual farmers who may have contracts for rice or cotton production or less flexible contracts for fixed perennial crops of citrus, grapes or nuts. Most flexible are the choices to grow other annual crops which can be altered year to year according to water availability and price, as well as anticipated commodity prices.
Figure 2: Southern NSW Murrumbidgee catchment 2006 to 2018 volume of irrigation water applied (GL) for different crops. Source: (Gupta et al., 2020)
The most significant water user in the Murrumbidgee catchment has been the rice industry, which faced the greatest cutbacks during the drought years (2007-09). Cotton areas have expanded to the point of recently exceeding the total water use by rice or any other crop. Grapevines have maintained relatively constant water use over time. Almond plantations are an emerging presence in the catchment with regard to water use; many young plantations are expected to require greater water volumes as they mature.
The researchers acknowledge Professor Jim Pratley and the Graham centre for supporting this work through the Pilot project funding scheme.
More information: firstname.lastname@example.org Tel: 02 6933 2921
Gupta, M., Westwood, T., Legg, P., & Hughes, N. (2020). MDB water market dataset. ABARES. https://www.agriculture.gov.au/abares/research-topics/water/mdb-water-market-dataset
Murray-Darling Basin Authority. (2020). Catchments in the Murray–Darling Basin. https://www.mdba.gov.au/water-management/catchments