During the morning of Sunday 25 February, thunderstorms produced heavy rainfall and flash flooding in the Australian Capital Territory (ACT).
Canberra Airport recorded more than 60 millimetres in less than five hours, more than the station’s monthly long-term average of 51.2 millimetres. Southwell Park, to the north of the central business district, received 124 millimetres in six hours. In the three hours to 10.45am, the Bureau of Meteorology (the Bureau) recorded 66.2 millimetres at Woolshed Creek, 43 millimetres at Oaks Estate and 39.2 millimetres at the boat harbour on Lake Burley Griffin. Sixty millimetres of rain were recorded in just an hour at Sullivan’s Creek, and the 24-hour total to 9.00am on 26 February was 97 millimetres.
The Bureau issued a severe thunderstorm warning at approximately 9.15am on the Sunday and cancelled it at approximately 1.20pm that afternoon.
The rainfall, described by the Bureau as an extreme weather event, caused flash flooding in parts of the city and forced several road closures. Just to the east of the city, rainfall at Woolshed Creek produced a one-in-a-100-year weather event. The city’s north was hit particularly hard, with apartments and homes flooded in O’Connor. In the inner north of the city, buses were diverted for much of the day, with Northbourne Avenue and surrounding streets closed for several hours. Bus services had returned to normal by 4.00pm.
The ACT State Emergency Service (ACT SES) received more than 250 requests for assistance from Canberrans hit by the deluge. All ACT SES teams were deployed across the territory to help with the ongoing clean-up, mainly dealing with localised flooding and a few calls about roof damage. SES teams were supported by ACT Fire and Rescue, ACT Rural Fire Service, the New South Wales State Emergency Service, the Australian Federal Police, Transport Canberra and City Services, and the Access Canberra Call Centre.
On Sunday evening, ACT SES advised of several locations that had been re-opened to the public. However, the Australian National University (ANU) experienced significant flooding and power interruptions across the campus and cancelled all classes and events scheduled for the Monday. The lower level of the Chifley Library, the biggest and busiest of the ANU’s five libraries, was flooded by half a metre of water. The flooding wiped out the library’s electrical, air conditioning and ventilation systems and IT infrastructure, and caused significant damage to microfilm collections, books, serials and journals relating to history, philosophy and politics. ANU’s inundation was most likely caused by changes to water flow from major construction works on the campus.
A number of outside events on the final day of the Royal Canberra Show, in the northern suburb of Mitchell, were postponed and restarted after the rain eased during the afternoon.
Canberra residents heeded warnings to keep clear of floodwaters; no injuries or fatalities were reported as a result of the floods.
The rain that produced the flooding was described by the Bureau as a one-in-a-100-year weather event.
A January 2018 report by the ACT Auditor-General found that new suburbs and multi-story developments in existing Canberra suburbs were putting extra pressure on the city’s stormwater system. The report indicated that stormwater infrastructure in many parts of Canberra would be unable to cope with major rain events.