A case study of 2022 Lismore flood in Australia: social impacts and frequency analysis

Flood is one of the worst natural disasters, which affects millions of people every year globally. There was a devastating flood in 2022 in the Northern Rivers region in Australia. The Lismore city witnessed 14.4 m flood level, recorded on 28 Feb 2022, the highest since flood recording started in Lismore. This flood displaced 30,000 people, washing away infrastructure including access roads, damaging homes and hundreds of landslips, soil and boulders tumbling down for kilometers. The disaster response by Engineers Without Borders (EWB) after the 2022 Lismore flood made a positive impact in the society. A flood frequency analysis (FFA) is conducted using FLIKE software to understand the severity of flooding in the Northern River basin. Annual maximum flood (AMF) is gathered at Station 203014 Wilsons River at Eltham, which is about 16 km from Lismore City. Data from 1958 to 2024 (67 years) is used in FFA. It is found that none of five selected probability distributions (log-Pearson Type 3 (LP3), Generalized Extreme Value (GEV), Generalized Pareto (GPA), Gumbel (EVD) and log-Normal (LN) distributions, fit the higher flood data satisfactorily. It is recommended that vulnerable people living in the worst-flood affected areas in Lismore should be relocated to nearby flood-safe towns to reduce overall flood damage and social impacts.