Murray–Darling Basin: Climate and water
- Total annual rainfall was below average and the lowest since the 2002–03 year.
- Streamflows were very low reflecting the below-average rainfall and poor soil moisture conditions.
- Annual streamflow in the Darling River was the lowest on record.
For further information on the region's climate and water conditions during the 2018–19 year scroll down this page or click on the links below:
About the region
- The Murray-Darling Basin region's climate ranges from sub-tropical in the north, to semi-arid in the west, and temperate in the south.
- Average rainfall across the region ranges from more than 2,100 mm in the highland areas in the southeast to less than 300 mm in the semi-arid areas in the west.
- Typically, streamflow in the northern part of the region reflects the sub-tropical rainfall distribution with higher streamflows in the late summer–early autumn months (January–March) following the higher summer rainfall period.
- Flow in the southern part of the region reflects the more temperate climate with higher flows in the late winter–early spring months (August–October) following winter rainfall.
Climate conditions
Rainfall
Figure C1 Annual and monthly rainfall deciles for the Murray–Darling Basin region during the 2018–19 year
- Total area-averaged rainfall for the year was 310 mm, less than the mean value of 459 mm and the region's lowest since 2002–03.
- Rainfall was very low across the northern part of the region during January–February 2019, the typically wetter months of the year. Large parts of the region recorded their driest January and February on record.
- In July and September 2018, rainfall was well below average across the entire central and southern parts of the region, respectively.
- The below-average rainfall throughout the spring 2018 and winter 2019 months was likely due to a positive phase of the Indian Ocean Dipole that influenced Australia's climate during those periods (see the Bureau's 2018–19 Climate Report for more information).
- Well above-average rainfall occurred across western and inland parts of the region during April 2019 due to thunderstorms associated with a large cloudband across the eastern interior of Australia.
Figure C2 Total monthly rainfall for the Murray–Darling Basin region during the 2018–19 year compared with the average and percentiles for the region
- Rainfall in November 2018 and March 2019 was above average. All other months were generally below average.
- Rainfall in September 2018 and February 2019 was well below the 10th percentile. It was the sixth driest September on record and the driest February since 1965.
Actual evapotranspiration
Figure C3 Annual and monthly actual evapotranspiration deciles for the Murray–Darling Basin region during the 2018–19 year
- Total area-averaged actual evapotranspiration was below average across most of the region, reflecting the dry conditions and low water availability across the region throughout the year.
- In February 2019, evapotranspiration was the the lowest on record across large parts of the north following the very low rainfall during January–February 2019.
- Above-average evapotranspiration occurred across western and inland parts of the region during May–June 2019. This was due to increased water availability following high rainfall over the eastern interior of Australia in April 2019.
Soil moisture
Figure C4 Annual and monthly soil moisture deciles for the Murray–Darling Basin region during the 2018–19 year
- Soil moisture in the root zone (0–1 m depth) was well below average across most of the region; some areas in the north experienced their poorest soil moisture conditions on record.
- Rainfall and soil moisture are typically closely aligned. For example, the very poor soil moisture conditions in the northern part of the region during January–February 2019, and in the southern and central parts of the region during July–September 2018, are due to the low rainfall that occurred across these areas during those months.
- Soil moisture conditions were only above average across large parts of the region during April–May 2019 following high rainfall over the eastern interior of Australia in April 2019.
- More information on soil moisture distribution across the Murray–Darling Basin region is available in the Australian Landscape Water Balance.
Streamflow responses
Streamflow
Figure C5 Key flow gauging stations along the main rivers within the Murray–Darling Basin region
- The Murray and Darling rivers are the two primary river systems within the region. Streamflow in the River Murray is influenced by dam operations and diversions for consumptive use.
- Most of the major tributaries of the Murray and Darling rivers in the southern part of the region represent predominantly regulated rivers; most of the major tributaries in the north represent unregulated rivers.
Figure C6 Total monthly flow for major rivers in the Murray–Darling Basin region during the 2018–19 year compared with average and percentiles
- Streamflows were well below average for most of the year, which reflects the low rainfall and poor soil moisture conditions experienced across the region.
- Total annual flow in the River Murray at Lock 1 Downstream (Station A4260903) was 1,756 GL compared to the average value of 5,924 GL. This was the river's lowest annual flow since 2009–10.
- Annual streamflow in the Darling River was the lowest on record. No flow occurred in the river for a 10-month period between September 2018–June 2019.
- In April 2019, streamflow in the Warrego River was well above average due to high rainfall during that month over the river's catchment area in the northwest of the region.
- More information on streamflow distribution across the Murray–Darling Basin region is available in the Regional water information.