The term ‘unprecedented’ is often used in the media to describe contemporary extreme weather events. The magnitude of these extreme events is often not witnessed or recorded previously. However, evidence of extreme floods from the past have been found throughout Australia and elsewhere. Physical evidence from fluvial sedimentary records can provide critical insight into the magnitude and frequency of significant flood events that occurred well before gauging began. Many of these are of greater magnitude than in the records.
Palaeoflood hydrology is the study of floods which occurred prior to human observation (Baker, 1987). A common technique in a palaeoflood study is the use of fluvial sedimentary records in low-energy depositional areas. Hydraulic modelling and dating techniques provide information to the magnitude and frequency of the past extreme flood events through these sedimentary records found in the physical environment.
In Australia, there has been a significant increase in palaeoflood studies in the last decade with the discipline evolving from academic research to real-world application. The application of these records is discussed in this paper. Importantly, a review of these recent Australian palaeoflood studies provides clear evidence that larger floods have occurred in the past.
‘Unprecedented’ floods are generally attributed to climate change. However, the reality may be far more stark. Such floods, and many larger, are not unprecedented. If such extreme events have occurred in the past, then palaeoflood information can help us conceive and understand the potential for larger floods in the future due to accelerated climate change.