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<p>The intensification of extreme rainfall under climate change necessitates a paradigm shift in design rainfall estimation to enhance flood-risk assessment and infrastructure resilience. However, the current Australian Intensity-Frequency-Duration (IFD) derivation, based on Australian Rainfall and Runoff 2016 (ARR2016) guidelines, assumes temporal stationarity, presuming that the average frequency and intensity of rainfall extremes remain invariant over time, restricting their ability to capture evolving hydroclimatic extremes under changing climatic condtions. This study attempts to refine this practice by integrating high-resolution downscaled rainfall projections from ACCESS-1-0-CCAM models under RCP4.5 and RCP8.5 emissions scenarios, disaggregated into finer temporal resolutions using the Modified-Chowdhury-Indian-Meteorological-Department (MCIMD) approach. Return-level estimates were derived through Generalised-Extreme-Value (GEV) distribution, enabling a comparative assessment against the baselines—ARR2016 and unaltered stationary design rainfall estimates. Findings indicate a significant intensification of short-duration rainfall, with projected increases of 10–59% (RCP4.5) and 38–64% (RCP8.5), exacerbating urban flash flood-risks. Medium-duration events exhibit moderate increases (18–35%), while longer-duration extremes demonstrate attenuation (10–20%), reflecting shifts in the relative dominance of convective and synoptic-scale rainfall processes. Comparative analysis against the baseline return level estimates reveals substantial discrepancies, emphasising the limitations of existing design methods. The study findings advocate for integrating climate-informed rainfall estimation frameworks that account for evolving atmospheric and hydroclimatci variability, ensuring effective flood mitigation strategies and adaptive infrastructure planning. Furthermore, the study provides critical insights into refining Australian design rainfall standards, reinforcing the urgency for climate-responsive engineering practices under intensifying rainfall extremes.</p>

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Climate change impacts on design rainfall extremes employing empirical disaggregation-based rainfall intensities: a case study for East Melbourne

  • 期刊论文

  • 发表日期：

    2025年11月26日

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  • Harshanth Balacumaresan,
  • Iqbal Hossain,
  • Monzur Alam Imteaz

摘要

The intensification of extreme rainfall under climate change necessitates a paradigm shift in design rainfall estimation to enhance flood-risk assessment and infrastructure resilience. However, the current Australian Intensity-Frequency-Duration (IFD) derivation, based on Australian Rainfall and Runoff 2016 (ARR2016) guidelines, assumes temporal stationarity, presuming that the average frequency and intensity of rainfall extremes remain invariant over time, restricting their ability to capture evolving hydroclimatic extremes under changing climatic condtions. This study attempts to refine this practice by integrating high-resolution downscaled rainfall projections from ACCESS-1-0-CCAM models under RCP4.5 and RCP8.5 emissions scenarios, disaggregated into finer temporal resolutions using the Modified-Chowdhury-Indian-Meteorological-Department (MCIMD) approach. Return-level estimates were derived through Generalised-Extreme-Value (GEV) distribution, enabling a comparative assessment against the baselines—ARR2016 and unaltered stationary design rainfall estimates. Findings indicate a significant intensification of short-duration rainfall, with projected increases of 10–59% (RCP4.5) and 38–64% (RCP8.5), exacerbating urban flash flood-risks. Medium-duration events exhibit moderate increases (18–35%), while longer-duration extremes demonstrate attenuation (10–20%), reflecting shifts in the relative dominance of convective and synoptic-scale rainfall processes. Comparative analysis against the baseline return level estimates reveals substantial discrepancies, emphasising the limitations of existing design methods. The study findings advocate for integrating climate-informed rainfall estimation frameworks that account for evolving atmospheric and hydroclimatci variability, ensuring effective flood mitigation strategies and adaptive infrastructure planning. Furthermore, the study provides critical insights into refining Australian design rainfall standards, reinforcing the urgency for climate-responsive engineering practices under intensifying rainfall extremes.