A modelling framework for predicting flood damage costs in coastal areas caused by the compounding effects of rainfall, sea level rise and urbanisation has been developed by QUT researchers.
- Study of the compounding effects of rainfall, sea level rise and urbanisation
- Annual average damage cost was 78 per cent higher in 2040 compared to 2017 level
- Prediction tool could be used for any coastal area regardless of geographic location
Professor Ashantha Goonetilleke from the School of Civil and Environmental Engineering said little research had been done on the integrated and simultaneous influence of future changes to rainfall, urbanisation and sea level rise in coastal areas.
"Future flood risks and associated flood damages are expected to be strongly influenced by the increase in urbanisation and climate change-driven rainfall and sea level changes," Professor Goonetilleke said.
"Using these three variables, we developed a comprehensive flood damage and hazard prediction model to assess the flood scenarios for 2040, 2070 and 2100 for urban coastal regions, where 37 per cent of the world's population lives.
"We chose 30-year intervals to capture climate change and its influence on rain and sea levels and developed 27 future flood scenarios from these variables."
Professor Goonetilleke said the results showed that changes to the seasonal distribution of rainfall significantly influenced the average annual damage cost caused by flooding for each of the time horizons.
"Compared to the base year 2017, the annual average damage cost was 78 per cent higher for 2040, 197 per cent for 2070 and 351 per cent higher for 2100.
"The effects of urbanisation and sea level rise varied but the model predicted that by 2040 while urbanisation would exacerbate annual flood damage, rising sea levels would be the greater contributor in 2040 and 2070."
Professor Goonetilleke said the study had focused on pluvial (heavy rainfall) and fluvial (overflowing water course) floods because the ability of floodwater to discharge to the ocean is hampered by higher sea levels.
"We know that climate change is radically affecting the hydrological cycle – the circulation of water from earth into the atmosphere and back again – leading to temperature and moisture variations which may cause severe storm surges and coastal floods.
"These climate change-driven effects are expected to bring frequent, extreme rain events and urban places are at risk of heavy rainfall floods because a significant land area is covered by impervious surfaces that prevent water infiltration.
"Our flood damage assessment model is essential for calculating flood risk to produce effective strategies to reduce damage and mitigate flooding for flood-vulnerable communities.
"Our model can guide modelers and decision-makers in assessing the compounding flood damage costs for future flood management in any area regardless of geographic location."
The research team comprised Associate Professor Prasanna Egodawatta, Professor James McGree, Professor Ashantha Goonetilleke from QUT and Dr IP Gustave S Pariartha from QUT and Udayana University, Indonesia; Dr Shubham Aggarwal and Dr Srinivas Rallapalli from Birla Institute of Technology and Science, India.
Compounding effects of urbanization, climate change and sea-level rise on monetary projections of flood damage was published in the Journal of Hydrology.
