Perth: Outlook for 2019 Account
as at 20 February 2019
- Above-average winter rainfall contributed to improved groundwater recharge and surface water runoff in the first few months of the year.
- Overall the 2018–19 year is likely to be drier than average.
- Storage levels at 30 June 2019 are expected to be slightly higher than at the same time last year.
For further information on the expected inflows and future commitments for the region during the 2018–19 year scroll down this page.
Future prospects
Figure S20 Water outlook for the Perth region for 2018–2019
- There is a surplus of available water assets and future water rights over water liabilities and future water commitments that are expected to be settled within 12 months of the reporting date.
Expected inflows
Figure S21 Rainfall deciles for the Perth region for 1 July 2018–20 February 2019
- Rainfall during winter (June–August 2018) was above average and the region experienced its wettest August since 1965; rainfall during spring and summer (September 2018–February 2019) was well below average.
Figure S22 Storage levels for the Perth region from February 2018 to February 2019
- Storages were 52% full in mid-February compared to 45% full at the same time last year.
- Storage volumes reached their highest levels since 2009 in September–October 2018.
- The improvement in storage levels resulted from increased inflows, low urban usage of surface water, and 'banking' of desalinated water in the storages.
Figure S23 Groundwater levels in the Gnangara Mound from January 2018 to January 2019
- Groundwater levels in January 2019 were slightly higher than at the same time last year due to the above-average winter rainfall (June–August 2018).
Figure S23 Chance of exceeding median rainfall for the Perth region for March–May 2019
- According to the Bureau of Meteorology's climate outlook (from 14 February 2019), parts of the region toward the coast are likely to have a drier than average autumn (March–May 2019), while eastern parts of the region show no strong tendency towards wetter or drier than average autumn conditions.
- Considering the wet start to the 2018–19 year, the dry spring and summer, and the mixed autumn outlook, total annual rainfall for the region is expected to be below average.
- Surface water storage inflows occur mainly in winter and early spring in response to winter rainfall. The majority of these inflows for 2018–19 have now been received, and these are higher than in the previous several years.
- The good winter rainfall and the ramp up of the Groundwater Replenishment Scheme (stage 1) to its design capacity of 14 GL/year in 2018 will contribute to groundwater recharge; however, due to the expected lower annual rainfall, total recharge is likely to be lower than the previous year.
Future commitments
- Due to the improved surface water availability, surface water supply to the urban system is likely to increase this year. This may mean that the volume of desalinated water delivered to the urban system will be less than the previous few years. Groundwater supply to the urban system is likely to remain similar to the previous year.
- Usage by individual groundwater and surface water users and the irrigation scheme is expected to increase slightly due to higher irrigation demand during the dry summer.