A very dry month for the southeastern mainland increases rainfall deficiencies
Soil moisture details are reported when there are periods of significant rainfall deficits.
Soil moisture data is from the Bureau's Australian Water Resources Assessment Landscape (AWRA-L) model, developed through the Water Information Research and Development Alliance between the Bureau and CSIRO.
See: Australian Landscape Water Balance.
What is drought?
Go to Bureau Blog: What is drought?
Drought is a prolonged, abnormally dry period when the amount of available water is insufficient to meet our normal use. Drought is not simply low rainfall; if it was, much of inland Australia would be in almost perpetual drought. Because people use water in so many different ways, there is no universal definition of drought. Meteorologists monitor the extent and severity of drought in terms of rainfall deficiencies. Agriculturalists rate the impact on primary industries, hydrologists compare ground water levels, and sociologists define it by social expectations and perceptions.
It is generally difficult to compare one drought to another, since each drought differs in the seasonality, location, spatial extent and duration of the associated rainfall deficiencies. Additionally, each drought is accompanied by varying temperatures and soil moisture deficits.
Rainfall averages, variability and trends
- Average rainfall: How much rain do you expect?
- Rainfall variability: How consistent is rainfall in your area?
- Rainfall history: Check tables, graphs and data from your local weather station.
- Rainfall trends: Has your rainfall changed?
Lowest on record - lowest since at least 1900 when the data analysed begin.
Severe deficiency - rainfalls in the lowest 5% of historical totals.
Serious deficiency - rainfalls in the lowest 10% of historical totals, but not in the lowest 5%.
Very much below average - rainfalls in the lowest 10% of historical totals.
Below average - rainfalls in the lowest 30% of historical totals, but not in the lowest 10%.
Average - rainfalls in the middle 40% of historical totals.
Above average - rainfalls in the highest 30% of historical totals, but not in the highest 10%.
Very much above average - rainfalls in the highest 10% of historical totals.
Australian Government drought assistance
Department of Agriculture and Water Resources information and contacts:
- Know your weather
Know your weather. Know your risk.
- Water Information
Water resources assessments and forecasts
- Water and the Land
Weather and climate for primary industries
- Australian Bureau of Agricultural and Resource Economics and Sciences
(ABARES) is a research bureau within the Department of Agriculture, Fisheries and Forestry aimed at Australia's primary industries.
- Climate Change in Australia
Bureau/CSIRO website, including rainfall and temperature projections and impacts for the coming decades.
- CSIRO-BoM Drought-EC Report (July 2008)
An assessment of the impact of climate change on the nature and frequency of exceptional climatic events, and accompanying Supplementary Information.
Ex-tropical cyclone Esther helps ease rainfall deficiencies in some areas
Rainfall during the first three months of 2020 has been above average across large areas of Australia, including the eastern mainland. However, the size of the rainfall deficit accumulated over annual and longer timescales in the preceding months is very large over much of Australia. This means recent above average rainfall has not yet made up for this shortfall, and serious or severe rainfall deficiencies persists over very large areas at these longer timescales.
Additional widespread, above average rainfall is still needed to lift areas out of deficiency at annual and longer timescales and provide relief from the impacts of this long period of low rainfall (such as renewing water storages).
Whilst the Bureau of Meteorology's monthly Drought Statement focuses on rainfall deficiencies for periods up to two years' duration, we also monitor rainfall deficiencies and impacts on water resources on longer timescales such as the current severe multi-year drought affecting large parts of eastern Australia. This is discussed further below, and we have Special Climate Statements on this long dry period.
The role of climate change in rainfall reduction over southern Australia is discussed in State of the Climate 2018 which shows that parts of southwest Australia, and large parts of southeast and eastern Australia including parts of southeast Queensland and southern and eastern New South Wales, have seen substantial declines in cool season rainfall in recent decades.
The Climate Outlook for April to July, issued 2 April, indicates an increased chance of wetter than average conditions for most of Australia. The north and east coast, and Tasmania, have roughly equal chances of wetter or drier conditions.
8-month rainfall deficiencies
Rainfall deficiencies at the 8-month timescale, from August 2019 to March 2020, have decreased across most affected areas of Australia following above average rainfall across large areas during March. The progress of ex-tropical cyclone Esther in early March contributed to above average rainfall in an arc from the inland Kimberley in the northwest to the southeast of Australia.
However, serious to severe rainfall deficiencies still persist in several parts of the country: along the border of South Australia and New South Wales, extending into parts of western New South Wales, extending into parts of western New South Wales; in pockets of southern South Australia and across the far north of that State, extending into the southwest of the Northern Territory; in far eastern Victoria and some parts of southeastern New South Wales; pockets of southwest coast and west coast of Western Australia; a large area in the central to northeastern Top End in the Northern Territory and far northern Kimberley; and pockets of eastern Queensland, including the inland southeast.
24-month rainfall deficiencies
Rainfall deficiencies for the period from April 2018 to March 2020 have eased slightly across most of Australia, compared to those for the 23 months ending February 2020. However, the depth of the rainfall anomalies over this period is very great, in excess of 400 mm below average for the period over large areas of the east and north, and it will take several further significant rainfall events to turn around those long-term deficiencies.
Serious to severe rainfall deficiencies are in place for the 24-month period across much of the South West Land Division in Western Australia, parts of the Kimberley and the northeastern Interior District, and parts of the western Pilbara; much of the Northern Territory except areas of the east; much of South Australia; the southeastern quarter of Queensland; most of New South Wales; across northern Victoria and most of the eastern half of that State except parts of West and South Gippsland; and along the coast of northern and eastern Tasmania.
While the area of lowest on record rainfall for the period has again reduced month-on-month, areas of record low rainfall for the 24-month period persist in western New South Wales and adjacent eastern South Australia, areas along the New South Wales–Queensland border, parts of the southern coast of the South West Land Division and South Coastal District in Western Australia, and scattered pockets elsewhere.
Extended dry conditions over eastern Australia
Rainfall deficiencies have affected most of the New South Wales, Queensland and South Australian parts of the Murray–Darling Basin since early 2017, as detailed in the last update on the long-running dry and for 2019 in the Annual Climate Statement. These longer-term deficiencies also extended to parts of the New South Wales coast, particularly in the Hunter and Illawarra to southeastern districts, and to much of the eastern half of South Australia from Adelaide northwards. The deficiencies were most extreme in the northern Murray–Darling Basin, especially in the northern half of New South Wales and adjacent southern Queensland, where areas of lowest on record rainfall extended across large areas. Some of the largest rainfall deficiencies occurred in the upper catchments of some of the major tributaries of the Darling, including the Macquarie, the Namoi–Peel, and the Border Rivers.
A wetter start to 2020 has eased the severity of short-term deficiencies over much of eastern Australia and has provided a good start to the winter cropping season in many regions. However, the rainfall deficiencies were severe over an extended period so recovery will be a slow process. The impact on water resources is still evident, especially in northern parts of the Murray–Darling Basin. Significant deficiencies remaining at long-term timescales across many parts of the country. Averaged over the Murray–Darling Basin and New South Wales, the 36 months from April 2017 to March 2020 has been the driest such period on record. Average rainfall for the Murray–Darling Basin was 979 mm over the last 36 months, the only sub−1000 mm total in 120 years of record and around 30 mm lower than the second-driest (1011 mm from April 1900 to March 1903), whilst New South Wales received around 50 mm less rainfall than the next driest period, the 36 months from April 1900 to March 1903. Other areas affected by longer-term rainfall deficiencies include eastern Victoria, eastern and northern Tasmania, eastern South Australia except for the southeast and some parts of southwest Western Australia.
The dry conditions of the last three years were particularly acute during the cool season, which is important in many regions for generating runoff. April−October rainfall totalled across the three years was the lowest on record across large parts of western and eastern New South Wales. All three years had seasonal rainfall below 200 mm for New South Wales, with 2018 and 2019 both below 150 mm; there is no previous instance of two consecutive years below 150 mm, or three consecutive years below 200 mm. The very much below average November and December rainfall in 2019 over most of the main water catchments of New South Wales and the Murray–Darling Basin as a whole has further exacerbated the effect of low inflows to date. Rainfall in the first three months of 2020 rainfall has improved flows in parts of the Basin but total storages are still low, especially in the northern Basin (see Water section of this Statement).
Water storage levels remain low in the northern Murray–Darling Basin
Water storage levels increased in many of the major storages in the Murray–Darling Basin, but they decreased through the south resulting in the total storage across the Basin increasing only slightly to 32% of capacity.
Following the wetting of the landscape in January and February, the rainfall in March did result in some runoff into storages in the northern Murray–Darling Basin but total storage in the northern Basin remains at only 13.5%. The current level in the north is still similar to the storage levels in 2009, at the height of the Millennium drought in the north.
Despite slight increases, water storage levels in most major storages in the northern Murray–Darling Basin remain below 20% full. Exceptions include the downstream storages in the Condamine–Culgoa catchment where Chinchilla Weir on the Condamine River, and Lake Kajarabie (Beardmore) and Jack Taylor Weir on the Condamine River, all remain close to capacity.
The total storage in the southern Basin held steady at 37%. Minor increases were seen in the storages in the headwaters of the Lachlan and Murrumbidgee river valleys but otherwise decreases of up to 10% were seen across many of the southern storages. Lake Hume dropped another 6% this month to only 13% of capacity. It is expected that Lake Hume and other storages in the southern Basin will continue to decrease until late April while bulk downriver releases are still occurring and inflows are, on average, lower.
The most significant water storage increases this month were in the Menindee Lakes where lakes Wetherell and Pamamaroo increased from 0 to 83% and 39% respectively. Water levels started to increase in Lake Wetherell on 11 March and then in Pamamaroo Lake on 22 March. These two lakes are the smallest in the system, but the increase still equates to 256 GL which WaterNSW estimates is more than 12-months' town water supply. These water levels are expected to continue to rise with further flows making their way down the Darling River.
Darling River flows into Menindee Lakes
The river flows generated in February in the northern Murray–Darling Basin rivers have made their way down the Darling River system during March.
All of the major rivers in the Murray–Darling Basin have had some flow during March. A significant proportion of the water from the flooding in the Condamine–Culgoa River system in February was soaked up by dry riverbeds, waterholes, wetlands, and floodplains. A relatively small amount (less than 10 GL/day) did flow from the Culgoa River into Darling River from 1 March and continued to flow throughout March.
The Gwydir, Namoi, Macquarie, Castlereagh, and Border rivers (Barwon River tributaries) all contributed to the flow in the Darling River that reached the Menindee Lakes on 11 March. The water releases into the Lower Darling (downstream of Menindee Lakes) began at the end of March and the Darling is expected to reconnect with the Murray River in mid-April.
Following the flows in February in the upper reaches of the rivers in the north east of the Murray Darling Basin, the river levels have dropped back down to below average to lowest on record at some of the stations.
The Paroo River catchment in the far northwest of the Basin received significant rainfall in March resulting in flows of greater than 50 GL/day in the upper reaches. Flows from the Paroo River rarely reach all the way to the Darling River as, like the Condamine–Culgoa, most of the water flows out of the main channel into temporary and permanent lakes, wetlands, swamps, and floodplains.
Most of the rivers in the southern Basin remain average to lowest on record since 1980 but all major rivers continue flowing. The southern Basin is coming to the end of its irrigation season leaving river flows and storage levels to increase over the southern winter.
Urban water storages
Monsoon provides limited inflows to Darwin surface water storage
The monsoon trough and related monsoon conditions dissipated over northern Australia in mid-March, signalling the end of the monsoon season. The Darwin water storage levels did see some recovery in March, increasing by 9% to 68% of capacity, but this still falls well short of the significant increases common to the wet season.
Root-zone soil moisture (in the top 100 cm) increased through March over much of eastern and southwestern Australia, compared to February.
Soil moisture for March was above average over most of New South Wales; much of Victoria except the southwest and far east; the southern third of Queensland, extending north along the Capricornia Coast, and extending across the Channel Country; across much of the Northern Territory south of the Top End; across much of the inland Kimberley and the South West Land Division; and across nearly all of Tasmania.
Soils were drier than average for the month in Western Australia in an area extending from the western Kimberley and eastern Pilbara into the north of the Interior District, for an area of the inland southeast of Western Australia, and for scattered smaller areas of far eastern Victoria, western Victoria and southeastern South Australia which have been affected by long-term rainfall deficiencies.
Despite February and March being wet over large areas of eastern and western Australia, and some areas of the eastern mainland having above average rainfall for the January to March period, the influence of very low rainfall over longer timescales is still evident in the 12-month soil moisture for April 2019–March 2020, which was very much below average over very large areas of Australia.
Valuable increases in soil moisture in New South Wales
Root-zone soil moisture in March was above average to very much above average across most of the Murray–Darling Basin. There were increases in soil moisture across the New South Wales catchments of the Murray–Darling Basin during March. Notably the area around and northeast of Menindee, that had previously missed out, received some rain this month which increased soil moisture for the first time since May 2019.
Importantly there were also increases in soil moisture in the major water-yielding catchments of the Hume and Dartmouth dams in Victoria and the Macquarie River catchment in New South Wales. The increase in soil moisture along the Macquarie River brought some relief to areas around Bathurst, Orange, and Dubbo which have not seen major increases in soil moisture since the start of 2017. The wetter soils mean that any rain that does now fall is more likely to result in runoff into rivers and storages.
In contrast, soil moisture decreased through the previously flooded far northern Basin. The Condamine–Culgoa catchment in the northeast received significant rain in February and early March that caused widespread flooding, but this has now started to dry out. Despite decreases in soil moisture in the Condamine–Culgoa, March rainfall has led to increases in soil moisture across the Darling, the Warrego, and the Paroo catchments setting the stage for more flows in the Darling in April.
Soil mositure averaged over the 39-months since January 2017 remains at lowest on record across almost half of the Basin and will likely remain low without several months of above average rainfall. This long period of dry means that while there may now be surface soil moisture for grass to grow, vegetation and dryland crops have not yet had an extended period of moisture to recover and grow.
- March rainfall somewhat below average for Australia as a whole
- Rainfall above average along a band from the inland Kimberley, through the southern Northern Territory and southwest Queensland, much of New South Wales and northern Victoria, and Tasmania
- However, March rainfall below average for much of the northern tropics and parts of eastern Queensland, an area extending from the western Kimberley and eastern Pilbara into the northern interior of Western Australia, and along the coast of southeast South Australia and western Victoria
- At the shorter timescale—over the eight months since August 2019—rainfall deficiencies have decreased across most affected areas in the southern half of Australia
- Rainfall deficiencies have also decreased at longer timescales— such as the 24 months since April 2018—although the accumulated rainfall deficit is significant, and deficiencies over the longer period persist in much of Australia
- Soil moisture has increased across much of eastern and southwest Australia, and remains above average for large areas
- Water storage levels in the northern Murray–Darling Basin remain low despite some inflows
- Rivers in the northern Murray–Darling Basin deliver flow to the Menindee Lakes
Product code: IDCKGD0AR0