A new study has revealed that climate change influences short-term and long-term rainfall and flooding in different ways, shedding light on how rising temperatures impact local and regional water systems. Researchers from Austria have provided the first comprehensive analysis of this relationship, using over a century of high-quality weather data. Their findings, now published in Nature, have global implications for understanding how floods may intensify in different regions.
The study, led by Prof. Günter Blöschl of TU Wien (Vienna), shows that short-duration rainfall events lasting just a few hours have increased by 15% in the last 30-40 years. The main driver behind this increase is rising temperatures caused by climate change.
Warmer air holds more moisture, while increased ground-level heating intensifies vertical air movement, causing faster cooling and heavier precipitation. These findings are consistent across Austria, affecting both sides of the Alps, which experience different climate conditions. This suggests that short-term heavy rainfall is driven by local warming, rather than large-scale weather systems.
Such intense precipitation events are particularly concerning for smaller rivers and catchment areas, which are highly sensitive to sudden water inflows, leading to flash floods. This means urban and rural areas near smaller rivers are at higher risk of flooding due to short-term heavy rainfall events.
Long-Term Rainfall Trends Show a More Complex Pattern
In contrast, longer rainfall events lasting several days behave differently. Their frequency and intensity are influenced more by global climate patterns like El Niño, which is driven by ocean temperatures. This results in regionally variable effects:
- Some areas, such as parts of Italy, Spain, and Greece, may experience fewer prolonged rainfall events.
- Large rivers like the Danube are less affected by short-term rain but more influenced by multi-day weather systems, which means their flood risk depends on broader hydro-climatic trends.
Implications for Flood Risk Management
The study’s findings emphasize the need for a region-specific approach to flood risk assessment, distinguishing between short-term and long-term rainfall effects.
- Smaller rivers and urban drainage systems must be prepared for more frequent flash floods due to short-term intense rainfall.
- Larger river basins require long-term planning based on changing global weather patterns.
By recognizing these differences, policymakers, engineers, and city planners can develop better flood protection strategies to mitigate the growing risks posed by climate change.