Murray–Darling Basin: Climate and water overview
Climate conditions
Rainfall
The total area-averaged rainfall over the Murray–Darling Basin region during the 2014–15 year was 412 mm, which is less than the long-term area-averaged rainfall of 469 mm (based on the 1900–2015 period). There was a slight increase in total annual rainfall across the whole region of 6% compared to the 2013–14 year total of 388 mm (see the 2014 Account). Total annual rainfall ranged from more than 900 mm in the southeast part of the region to less than 200 mm in some areas across the western and central part of the region (Figure C13).
Figure C13 Total annual rainfall for the Murray–Darling Basin region during the 2014–15 year
Rainfall across the majority of the Murray–Darling Basin region was below average to very much below average for the 2014–15 year (Figure C14) with particulary dry conditions across Victoria. These rainfall conditions contributed to below average flows in the major river systems and storages in the region (see Streamflow).
Figure C14 Annual and monthly rainfall deciles for the Murray–Darling Basin region during the 2014–15 year
Climate across Australia was largely influenced by persistent near El Niño conditions in the Pacific Ocean from late 2014 and the Bureau of Meteorology declared an El Niño event in May 2015.
During the 2014–15 year, below average rainfall occurred for most months of the year (Figures C14 and C15). Above average rainfall occurred in the months of February–April 2015; however, the impact on total annual rainfall was minimal as these months are typically low rainfall months.
Below average rainfall was experienced during the typically wetter months of summer, which had a substantial impact on total annual rainfall. The low rainfall during this period contributed to the below average streamflow conditions in the region (see Streamflow).
Figure C15 Total monthly rainfall for the Murray–Darling Basin region during the 2014–15 year compared with the long-term average and percentiles for the region
Evapotranspiration
The total area-averaged potential evapotranspiration over the Murray–Darling Basin region during the 2014–15 year was 1,942 mm, which is above the long-term area-averaged potential evapotranspiration of 1,919 mm (based on the 1911–2015 period). Potential evapotranspiration was higher in the northern section of the region and lowest along the eastern boundary (Figure C16).
Figure C16 Total annual potential evapotranspiration for the Murray–Darling Basin region during the 2014–15 year
Potential evapotranspiration during the 2014–15 year was above average across most of the southern section of the region and average in the northern section of the region (Figure C17).
Figure C17 Annual potential evapotranspiration deciles for the Murray–Darling Basin region during the 2014–15 year
Soil moisture
Figure C18 shows that soil moisture, in the root zone (0 to 1m depth) for the 2014–15 year was generally below average across most of the southern section of the region and average in the central and northern section of the region (compared with the 1911–2015 period).
Figure C18 also shows monthly soil moisture deciles in the root zone (0 to 1m depth) during the 2014–15 year. Comparison of monthly rainfall and soil moisture deciles highlights the response of soil moisture to changes in rainfall aligning closely for the majority of months during the 2014–15 year.
Figure C18 Annual and monthly soil moisture deciles in the root zone (0 to 1m depth) for the Murray–Darling Basin region during the 2014–15 year
The combination of the generally below average rainfall conditions experienced across the region (see Rainfall) with the below average soil moisture observed in the upper, middle and lower reaches of the primary river catchments (Figure C18) contributed to below average flows in the Darling and Murray rivers (see Streamflow responses).
More information on soil moisture distribution across the Murray–Darling Basin region is available from the Australian Landscape Water Balance website.
Streamflow responses
Significant water events
In the northern section of the region, drought conditions eased slightly in Queensland but not enough to make a significant impact for agricultural production. In the southern sections of the region, Victoria recorded its lowest rainfall on record with drought conditions intensifing compared to the 2013–14 year (Murray–Darling Basin Authority [MDBA] 2016b)
Streamflow
The Darling River is one of the primary rivers within the Murray–Darling Basin region. The location of the key gauging station at Bourke (Station 425003) along the river is provided in Figure C8 in the 'Physical information'.
Total annual flow in the Darling River during the 2014–15 year was well below average; flow throughout the entire year was around the 10th percentile (Figure C19). The above average rainfall experienced during February–April 2015 did not result in above average streamflow in the river during this period, presumably because soil water stores and groundwater levels were relatively low following a sustained dry period.
Figure C19 Total monthly flow for the Darling River at Bourke during the 2014–15 year compared with the long-term average and percentiles for the river
The Murray River at Doctors Point, Albury (Station 409017), represents a regulated river reach downstream of major storages in the basin. Flows in this section of the river are influenced by dam operations and diversions upstream. The Ovens River at Peechelba (Station 403241) represents a predominantly unregulated river in the basin. The location of these key gauging stations along these rivers is provided in Figure C8 in the 'Physical information'.
Total annual flow during the 2014–15 year in the Murray River was less than the mean annual flow and approximately 8% less than the total flow observed during the 2013–14 year. Monthly flow for the majority of the year was less than the long-term average (Figure C20).
Figure C20 Total monthly flow for the Murray River at Doctors Point (Albury) during the 2014–15 year compared with the long-term average and percentiles for the river
Total annual flow during the 2014–15 year in the Ovens River was less than the mean annual flow and approximately 37% less than the total flow observed during the 2013–14 year. Flow during the typically wetter months of the year (June–October) was below the long-term average, particularly during August–October (Figure C21). The month of July recorded streamflow greater than 90th percentile mainly due to higher rainfall in the upper reaches of the catchment. These flow conditions reflect the below average rainfall conditions generally experienced across the region (see Rainfall). The above average rainfall experienced during February–April 2015 did not result in above average streamflow in the river during this period, presumably because soil water stores and groundwater levels were relatively low following a very dry summer period.
Figure C21 Total monthly flow for the Ovens River at Peechelba during the 2014–15 year compared with the long-term average and percentiles for the river
Major water reforms
Australian Government
The Basin Plan water trading rules commenced on 1 July 2014. The rules set out a consistent framework for water trading across the states, without duplicating existing state rules. They are designed to reduce barriers to trade, improve access to information and improve confidence in the operation of the market. With fewer restrictions on trade and better transparency of information there can be improved market confidence; and water traders can take advantage of market opportunities (MDBA 2016a).
The Murray–Darling Basin Authority will continue to work with the Basin states, territories and irrigation infrastructure operators to ensure effective compliance with these rules.
At 30 June 2015, 1,951 GL (71%) of the water recovery target of 2,750 GL had been recovered. During the 2014–15 year, the Australian Government invested a further $550 million on water-efficient infrastructure in farms and water delivery systems.
New South Wales
On 1 January 2015, State Water joined with the Sydney Catchment Authority and was renamed as WaterNSW. WaterNSW is responsible for developing infrastructure solutions for improved water supply and reliability, protecting water quality in its designated catchments, catchment protection in the drinking water catchments, asset management and flood operations and mitigation.
Australian Capital Territory
The 2015 Account for the Canberra region includes information on major water initiatives applicable for the Australian Capital Territory.