Probability-based assessment of wave and water-level conditions under sea-level rise in south-eastern Australian coastal waters

Sea level rise (SLR) can alter coastal water-levels and waves, thereby reshaping hydrodynamic hazards along south-eastern Australia. A 30-year hindcast based on a high-resolution coupled circulation–wave model is used to assess the effects of SLR on waves and water-level under five scenarios: 0, 0.5, 0.8, 1.0, and 1.4 m. Daily maximum wave height is classified into four intensity levels, from which a weighted wave condition index is derived. Daily maximum water-level is used to calculate percentile indices and four exceedance classes relative to the local mean level. Under present-day conditions, the weighted wave condition metric is largest in the open Southern Ocean south of Tasmania and lowest inside Bass Strait. Under SLR, changes in wave condition remain small and spatially heterogeneous. In contrast, water-levels show a stronger and more localized response, with higher levels in Bass Strait. Beyond the imposed mean SLR itself, SLR also drives additional local water-levels adjustments, thereby substantially increasing the probability of concurrent wave and water-level exceedance relative to present-day thresholds. These results provide spatially resolved, probability-based information on changes in wave and water-level conditions under SLR.