Up to 840,000 people in Austria reside in areas at risk of flooding, according to data released by the Ministry of Agriculture. While the figure is lower than earlier international estimates, the implications remain significant: over half a million Austrians are statistically likely to experience a “century flood” at least once in their lifetime. The regions at highest risk are in the Alpine areas and along the Danube River.
The Ministry’s flood risk management division conducted the evaluation by cross-referencing danger zones with residential registers. The analysis classified risk areas based on the probability of flooding within a 30-year, 100-year, and 300-year timeframe. The findings indicate that:
550,936 residents (6% of the population) live in areas with a 100-year flood risk.
99,758 people (1.1% of the population) are in regions facing a 30-year flood risk.
838,362 individuals (9.1% of the population) could be affected by extreme, 300-year flood events.
The data primarily accounts for residents with main addresses in these zones. Including secondary residences and workplaces would likely increase the affected numbers.
The frequency of heavy rainfall, a critical factor in flooding, is rising due to the climate crisis. According to recent studies by Geosphere Austria, periods of intense precipitation have become more common as warmer air holds more moisture. Compared to the 1960s, days with extreme summer rainfall now occur 30% more frequently, with autumn seeing a 40% increase.
Soil sealing, caused by urbanization and construction, exacerbates the issue, preventing water absorption and increasing runoff. The Climate Status Report 2021 also highlights the danger of flash floods following localized heavy rainfall, even in areas without constant water bodies. These floods can occur in unexpected places, including hillside runoff far from rivers or streams.
Regional Disparities in Flood Risk
Flood risk is significantly higher in Alpine regions, with Salzburg, Tyrol, Styria, and Vorarlberg showing the largest proportions of populations at risk:
Salzburg: 17% of residents face a 100-year flood risk.
Tyrol: 14% at risk.
Styria and Vorarlberg: 9.2% and 8%, respectively.
Some municipalities are particularly vulnerable. In Kalwang (Styria), nearly 90% of residents live in areas with a 100-year flood risk. Similarly, Stumm (Tyrol) and Goldwörth (Upper Austria) report that eight out of ten residents face the same threat.
By contrast, Lower Austria and Upper Austria have a relatively lower proportion of residents in 100-year flood zones, at 4.4% and 4.1%, respectively. Burgenland records the lowest percentage at just 2%. Vienna remains largely flood-safe, with only 0.2% of its population residing in such zones. During the most recent flooding in September, Vienna’s flood defenses proved effective, with just 3,601 residents out of over two million affected.
Flood Risk Management Plans Updated Every Six Years
Austria revises its flood risk management plans on a six-year cycle. The current second Flood Risk Management Plan (HWRMP), published in May 2022, will remain in effect until 2027. The plan identifies 416 areas with significant flood risk, covering 772 municipalities or districts in Vienna. The next steps involve developing standardized hazard and risk maps for 23,000 kilometers of river networks, which will guide the HWRMP and its mitigation measures.
A total of 36 actions are outlined, ranging from structural flood defenses to public awareness campaigns, aiming to reduce risks and safeguard affected populations.
