Storages swell with big rains
An above-average rain total for 2022 has established Wimmera and Grampians catchments well for the summer months, with water in storages at a level not seen since 1998.
Across the Wimmera, rain totals were about double annual averages.
Gwmwater-managed catchments are operating at 75.98 percent capacity as of January 4.
Wimmera Catchment Management Authority acting chief executive Luke Austin said late rain in 2022 had catchments in a good position.
“We’re seeing larger rain events — especially later in the year in high-rain years — rather than consistent rain across the year,” he said.
“We saw a similar pattern of a large rain event in September 2016, but I don’t think there’s any real trend of wet and dry years.
“Averages don’t tend to indicate how much rain we will experience as we will continue to see low-rain years or major rain events like we did last year.”
Across the Wimmera, rain for 2022 ranged between 650-millimetres and 900-millimetres — well above average.
Horsham gauges captured 669.6mm for the year, compared with an average of 365.5mm; and 100mm more than in 2011 when the regional city last experienced a flood.
Stawell gauges recorded 661.2mm for the year — 187.2mm more than average; while Ararat received 888.5mm compared to an average of 581.9mm.
Nhill, Warracknabeal and Edenhope were among the areas of lower rain for the year.
Nhill recorded 578.4mm compared to a 342.7mm average, gauges in Warracknabeal recorded 601.6mm compared to a 374mm average, and Edenhope recorded 665.4mm of rain compared to an annual average of 568.5mm.
Mr Austin said catchments had returned to ‘about normal’ operating levels after a large amount of water flowed through last year.
“We’re not expecting any major changes to the catchment soon unless we have another major rain event, so it’s looking pretty good,” he said.
“It’s good from both an environmental and recreational opportunity perspective. People are enjoying water sports on various lakes and our wetlands that haven’t seen water for some time are now great habitats for different animals and birds.”
Gwmwater water resources manager Kym Wilson said 2022 winterspring inflow to Grampians reservoirs was above average.
“This was the result of consistently above-average rain through August, September, October and November,” he said.
“Over recent decades, Grampians reservoirs have experienced multiple years of low inflow, followed by a single year of above average inflow, significantly boosting water storage levels. The pattern of wetter and drier years is influenced by climate factors.”
Grampians catchments held more than 425,750 megalitres as at Wednesday last week.
Catchments last held similar levels in 1997 — the beginning of the millennium drought.
The historic average inflow to Grampians catchments is 199,000 megalitres, however, since 1997, average inflow has been 85,000 megalitres.
In 2022, there was 300,000 megalitres of inflow to catchments.