Climate change plays a more significant role in amplifying flooding than extreme rainfall, a new study by the Helmholtz Centre for Environmental Research (UFZ) has suggested.
The study, Evidence from 2024 Storm Boris indicates anthropogenic climate change amplifies floods more than extreme precipitation, which was published in the Science Advances journal, examined the level to which 2024’s Storm Boris brought extreme precipitation and severe flooding to large parts of Central and Eastern Europe.
Building on previous studies that suggested that global warming intensified the rainfall associated with Storm Boris, the UFZ researchers combined climate simulations with two hydrological models to determine how shanges in precipitation affected river runoff and flood peaks.
According to the researchers, rainfall during the storm would have been between 6% and 9% lower without human-induced climate change. However, peak river flows would have been an average of 14–22% lower.
“The soil can initially absorb some of the rain during a heavy rainfall event,” commented lead author Peter Miersch. “But eventually the soil becomes saturated, and every additional millimetre of rain flows directly into the river.”
Exceeding the thresholds
The researchers used two climate models and two hydrological models, with all combinations producing the same general finding: flood peaks increased considerably more than precipitation. The findings are ‘particularly relevant’ for areas that have implemented flood protection measures based on specific flood thresholds, they added.
“If climate change increases extreme precipitation by 10%, it does not mean flooding will increase by only 10%,” added co-author Prof. Dr Jakob Zscheischler, a climate researcher at the UFZ and Professor of Data Analytics in Hydro Sciences at TUD Dresden University of Technology. “It could also be 20%. If flood levels exceed the thresholds for which flood protection measures are designed, extensive damage can occur very quickly.”
A full picture
As a result, flood-risk assessments and adaptation strategies should consider more than changes in extreme precipitation, the researchers noted.
‘When assessing future risks and developing adaptation strategies, it is therefore important to consider the entire process from the weather event to river discharge,’ the report said. Read more here.
