Climate change and flooding in Regensburg: is there a connection?

By Josef Anhamm · Published · Updated

Historic architecture and reflections in Regensburg, Germany by the Danube River.

Updated in October 2026: the gauge records, the climate-attribution evidence, the status of Regensburg’s flood-protection projects and the insurance figures in this article have been re-checked against official German sources (listed at the end). Earlier versions overstated the climate attribution of the 2013 flood and described the Unterer Wöhrd project as under construction; both are corrected below.

Quick answer: The Danube at Regensburg’s Eiserne Brücke gauge reached its three highest recorded levels in 1988 (6.59 m), 2002 (6.60 m) and June 2013 (6.82 m). The 2013 flood was driven by an exceptionally wet May and four days of heavy rain; no study we could verify puts a number on climate change’s role in that specific flood. The German Weather Service (DWD) did quantify it for the May-June 2024 rainfall in southern Germany: about 1.4 times more likely, with a wide uncertainty range. Regensburg’s flood defences are still incomplete: the €55 million Unterer Wöhrd scheme was still in its planning-approval procedure in May 2026.

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Climate change and flooding are reshaping risk even in historic river cities with centuries of flood-management experience. Regensburg, Germany - a UNESCO World Heritage city at the confluence of the Danube and Regen rivers in Bavaria - is a well-documented case study because its gauge records, flood-protection plans and the German debate on flood insurance are all public. For U.S. facility managers and homeowners evaluating their own flood exposure, it shows how long public defences take to build, why a city’s highest recorded flood is not the flood it plans for, and what attribution science can and cannot say about a single event.

This matters well beyond Germany’s borders. The same physical mechanism driving the Danube’s rising flood levels - a warmer atmosphere holding more moisture, released as heavier and more concentrated rainfall - is the mechanism behind the flooding our own research documents in heavy rainfall and flooding trends across the U.S. Regensburg simply gives us more data, collected over a longer period, with more rigorous attribution science behind it, than most American case studies currently offer.

Key takeaways

  • The Danube’s three highest levels at Regensburg’s Eiserne Brücke gauge were 6.59 m (March 1988), 6.60 m (August 2002) and 6.82 m (June 2013), according to the Bavarian Flood Information Service.
  • Larger floods happened before the modern record: the Danube carried an estimated 3,880 m³/s at Regensburg-Schwabelweis in 1845, against 2,670 m³/s in 2013.
  • The German Weather Service (DWD) attribution study usually quoted for Bavaria covers the May-June 2024 rainfall, not 2013: it found climate change has made such rain about 1.4 times more likely (range 0.8-4.4).
  • Under §78 of the German Water Act, building in designated flood zones is prohibited in principle and allowed only by individual exception.
  • About 41% of German homes still have no flood or heavy-rain cover (GDV, end of 2025); a draft law making the cover a standard part of new building policies is expected in 2027.

Climate change and flooding: the Regensburg case study

Regensburg sits at the confluence of the Danube and Regen rivers in Bavaria, Germany - a location that has shaped the city’s flood exposure since its founding as a Roman legionary camp nearly 2,000 years ago. The Danube here drains a large upstream catchment across southern Germany, which means that sustained rainfall anywhere across that basin - not just locally - can push the river to dangerous levels days later in Regensburg itself. This is structurally similar to how large U.S. river systems like the Mississippi or Missouri accumulate flood risk from rainfall hundreds of miles upstream.

Highest Danube levels at Regensburg (Eiserne Brücke gauge)

1988

6.59 m
28 March

2002

6.60 m
14 August

2013

6.82 m
4 June, highest on record

Source: Bavarian Flood Information Service (HND), gauge statistics for Regensburg Eiserne Brücke.

Each of these floods edged past the previous high-water mark at the gauge. In March 1988, the Danube reached 6.59 meters; in August 2002 it reached 6.60 meters, one centimeter higher; and on 4 June 2013 it peaked at 6.82 meters, 23 centimeters above the 1988 mark. The 2013 flood followed an exceptionally wet May that left soils at their wettest since measurements began in the 1960s, then four days of heavy, persistent rain from 30 May to 2 June (Federal Institute of Hydrology, BfG). Hydrologists describe this combination of saturated ground and strong, but not extraordinary, rainfall as the key driver of the flood (Schröter et al., 2015).

Water levels are only part of the picture. Measured by discharge, the Danube has carried more water at Regensburg before: the Bavarian Flood Information Service lists an estimated 3,880 m³/s at the Schwabelweis gauge in March 1845 and several 19th-century floods above 3,000 m³/s, against 2,670 m³/s in June 2013. The service also cautions that historic water levels are only partly comparable with today’s, because river and floodplain changes alter the level reached by the same flow.

The 2013 flood was not only a German event: the same rain also caused severe flooding in Austria and the Czech Republic. In Bavaria alone, the damage reached around €1.3 billion, and more than €100 million had to be spent on repairing state-owned waterways and flood-protection installations (Bavarian State Office for the Environment) - a reminder that flood defenses can themselves be damaged by the events they are built for.

What the climate attribution science actually shows

Attribution science compares observations and climate-model simulations of today’s climate with a counterfactual climate without human-caused warming, and estimates how much warming has changed the probability or intensity of a given type of event. Earlier versions of this article stated that the German Weather Service (DWD) found climate change made the 2013 Danube flood “10 times more likely”. That was wrong: the DWD study it relied on concerns a different event, and the two figures quoted (10 times, and a return period shortened from 40 to 30 years) were not consistent with each other.

What the DWD actually published is an attribution study of the late May to early June 2024 rainfall in Bavaria and Baden-Württemberg, which flooded rivers along the Danube, Neckar and Main, forced more than 6,600 evacuations and cost six lives. It found that climate change has already increased the probability of comparable rainfall in the region - today a roughly 30-year event - by a factor of about 1.4, with a range from 0.8 to 4.4 that includes a possible decrease, and its intensity by about 4%. In a climate 2 °C warmer than around 1900, the models show a further increase in probability by a factor of 1.2. Bayerischer Rundfunk summarised this as such a flood occurring every 30 rather than every 40 years. The DWD itself stresses the large uncertainties.

Regensburg’s own design values point in the same practical direction. The 100-year design discharge (HQ100) at the Schwabelweis gauge is 3,400 m³/s - about a quarter more than the 2013 peak - and the 2013 flow sits between the gauge’s 20-year and 50-year values (HND, Schwabelweis gauge statistics). In other words, the highest level ever measured in Regensburg is not the flood its defenses are designed for.

Why this matters for U.S. flood risk assessment

If even a long, well-documented gauge record like Regensburg’s sits well below the city’s design flood, a few decades of local flood history are a weak guide to future risk. Our guide on determining your home’s flood risk explains why relying purely on historical FEMA flood maps can understate real exposure.

One structural difference between German and U.S. flood policy is worth understanding, because it shapes how a city like Regensburg manages risk at the property level. Under §78 of the German Federal Water Act (Wasserhaushaltsgesetz, WHG), erecting or extending buildings inside officially designated flood zones is prohibited in principle - not merely discouraged through insurance pricing or building-code requirements. The authority may grant an exception only for an individual project that does not significantly reduce flood retention (or compensates for it), does not worsen water levels or flow, does not impair existing flood protection and is built in a flood-adapted way.

In Regensburg, erecting or altering structures in the designated Danube and Regen flood zones needs a water-law permit under §78 WHG from the city’s environmental office, in addition to the building permit. Smaller works - adding a storey, converting a roof, dormers, balconies or canopies above the HW100 line, and parking spaces that do not raise the ground - must be notified to the same office (City of Regensburg).

This stands in fairly sharp contrast to how many U.S. jurisdictions handle Special Flood Hazard Areas, where construction is typically still permitted provided it meets elevation and floodproofing requirements under the National Flood Insurance Program, rather than being prohibited in principle. The German approach trades flexibility for a much lower baseline of new exposure - but it does nothing to reduce the risk already embedded in centuries of existing construction along the Danube, which is precisely why the infrastructure and insurance questions below matter so much in Regensburg’s case.

How Regensburg is responding - and what it costs

Regensburg’s flood-protection programme predates the 2013 flood. The Regensburg water management office and the city began it in 2001 and divided the urban area into 18 sections, each designed to protect against a 100-year flood. By May 2023, five sections had been built; the programme’s total volume was put at around €150 million, of which €35 million had been spent (Bayerische Staatszeitung, 5 May 2023).

The most recent completed section is the Westhafen (western harbour), finished in 2022. It consists mainly of a reinforced-concrete wall between 0.9 and 2.7 meters high, built as a visible sheet-pile wall in the port area. Before it existed, a 100-year flood would have inundated an area the size of 112 football pitches in the Westhafen and eastern districts, affecting about 5,000 residents and around 380 businesses. It cost €10 million, shared equally by the city and the Free State of Bavaria.

The Unterer Wöhrd, an inhabited island in the Danube with about 140 houses, is the next and more difficult step. A continuous wall around a residential island is a hard planning problem, and in May 2026 the scheme was still in its planning-approval procedure: 57 objections had been lodged, the public hearing had not been scheduled, and the city expected construction to start in two to five years and take about five years. The current estimate of €55 million, 80% paid by Bavaria and 20% by the city, excludes price increases. A local residents’ group has asked for property-level protection of the houses to be examined as an alternative (Regensburg Digital, 18 May 2026).

Regensburg’s programme is part of a larger state effort. More than €4 billion has been invested in flood protection in Bavaria since its flood-protection programmes began in 2001, and the current programme, PRO Gewässer 2030, plans a further €2 billion for state flood-protection measures by the end of 2030 (Bavarian State Parliament, printed paper 19/2595).

ProjectCostStatusApproach
Westhafen section€10 millionCompleted 2022Reinforced-concrete wall and sheet-pile wall
Unterer Wöhrd≈ €55 million (estimate)Planning approval pending (May 2026); about 5 years of construction once startedProtection of an inhabited river island
Whole Regensburg programme (18 sections)≈ €150 million5 sections built by 2023; €35 million spentSection-by-section 100-year protection

The lesson for U.S. property owners

Regensburg’s programme has been running since 2001, and some sections are still in planning. That timeline is typical for large-scale municipal flood infrastructure anywhere, including comparable U.S. river and coastal flood-control projects. In the meantime, individual buildings inside and outside the officially protected perimeter still need their own protection. Our guide to flood protection systems for your home covers options that don’t require waiting on multi-year public works timelines.

The flood insurance gap: a warning sign, not just a German problem

Perhaps the most striking parallel to the U.S. flood insurance situation is unfolding in Germany right now, in real time, as this article is being updated. Standard German homeowners insurance (Wohngebäudeversicherung) covers fire, storm, hail, and water damage from burst pipes - but explicitly excludes damage from flooding, heavy rain, and landslides unless the policyholder has purchased a separate add-on called “Elementarschadenversicherung” (elemental damage insurance). This is structurally almost identical to how standard U.S. homeowners insurance excludes flood damage, requiring a separate NFIP or private flood policy.

The scale of the resulting coverage gap in Germany is real, though smaller than it once was: according to the German Insurance Association (GDV), about 59% of German residential buildings had natural-hazard cover at the end of 2025, up from 41% in 2017 - which means roughly 41% of German homes still have no flood or heavy-rain coverage at all. The gap became a major political issue after the 2021 Ahr Valley flood, which killed 135 people in the valley and left many uninsured homeowners facing ruin. In September 2026, Federal Justice Minister Stefanie Hubig presented key points for a reform: every new residential building policy would have to include natural-hazard cover, existing policyholders could extend their cover, but there would be no full compulsory insurance on the model of motor liability. A draft bill is expected in the first quarter of 2027 (GDV).

As of this update, no requirement has been enacted. Premiums depend on the flood risk at the address, which insurers assess with their ZÜRS zoning system. 2025 was a quiet year: natural hazards caused about €1.4 billion of insured property losses in Germany, of which perils other than storm and hail - including flood and heavy rain - accounted for about €400 million across roughly 88,000 claims, compared with €4.4 billion in total in 2024 (GDV).

Why U.S. readers should watch this debate

Germany’s planned shift toward natural-hazard cover as a standard part of new building policies is a policy experiment the U.S. has not run at national scale. If it goes ahead, it could offer real-world evidence on whether default inclusion meaningfully closes the flood insurance gap - evidence directly relevant to U.S. debates about underinsurance in FEMA-mapped flood zones.

What this means if you own property near a river

Pulling together the flood chronology, the attribution science, the legal framework, and the insurance debate, Regensburg offers a genuinely instructive template for how U.S. property owners near rivers or in flood-prone regions should think about their own exposure.

  1. Historic flood records can understate future risk - sometimes by a wide margin. Regensburg’s 100-year design discharge is about a quarter higher than its record 2013 flow, and 19th-century floods carried more water than any flood in living memory. If your area’s flood zone designation is based on a short historical record without a climate-adjusted projection, it may already be outdated. See our guide on determining your home’s flood risk to check whether your local data reflects current climate trends.
  2. Municipal protection takes years, sometimes decades, even with strong funding and political will. Regensburg’s programme started in 2001; its Unterer Wöhrd section was still awaiting planning approval in 2026 and needs about five years to build - a reminder that public infrastructure timelines rarely match the urgency of individual household risk.
  3. Don’t assume your insurance covers flood damage by default. Just as German homeowners insurance excludes flood damage without a separate Elementarschadenversicherung add-on, U.S. homeowners insurance excludes flood damage without a separate NFIP or private flood policy. The roughly 41% German coverage gap is a warning about how easy it is to assume coverage that doesn’t actually exist.
  4. Layer building-level protection with insurance rather than choosing one or the other. Combining automatic flood barriers with adequate flood insurance addresses both the physical and financial sides of river flood exposure while larger public infrastructure projects are still being completed.
  5. Watch how strict floodplain construction rules evolve in your own area. Germany’s in-principle building ban under WHG §78 is stricter than most U.S. floodplain regulation, but the underlying logic - that new construction in known flood zones compounds future risk and cost - is increasingly informing U.S. floodplain policy discussions as well.

Conclusion at a glance

The record

Highest Danube levels at Regensburg: 6.59 m (1988), 6.60 m (2002), 6.82 m (2013); larger discharges occurred in the 19th century.

The science

No verified attribution figure for the 2013 flood; the DWD found climate change made the May-June 2024 rain in southern Germany about 1.4 times more likely.

The infrastructure

Programme running since 2001; Westhafen (€10M) completed in 2022; Unterer Wöhrd (≈ €55M) still in planning approval in 2026.

The insurance gap

About 41% of German homes carry no flood coverage; a draft law on standard natural-hazard cover is expected in 2027.

What to take away

Even a well-funded, legally strict flood management program takes decades to build out fully, and insurance coverage gaps persist even in a country with strong flood-risk awareness. Building-level protection and adequate insurance both remain necessary, in Regensburg and in any U.S. flood-prone location, regardless of how much collective infrastructure exists.

FAQ

Why is Regensburg a useful flood case study for U.S. readers specifically?

Regensburg offers an unusually complete public record: a long gauge history with official extreme-value statistics, documented flood-protection projects with costs and timelines, a strict legal floodplain framework, and an active national insurance debate. That combination makes it a more instructive case study than most single-event examples.

How much worse has Regensburg’s flood risk actually gotten?

The Danube’s three highest levels at the Eiserne Brücke gauge were 6.59 meters in 1988, 6.60 meters in 2002 and 6.82 meters in 2013. The 2013 flow (2,670 m³/s at Schwabelweis) was still below the 100-year design discharge of 3,400 m³/s and below several 19th-century floods, so the city plans for floods larger than any it has measured in modern times.

What does climate attribution research say about flooding in Bavaria?

The German Weather Service’s attribution study of the May-June 2024 rainfall in Bavaria and Baden-Württemberg found that climate change has made comparable rain about 1.4 times more likely (range 0.8-4.4) and about 4% more intense, with a further increase expected in a 2 °C warmer climate. We found no study that quantifies climate change’s role in the 2013 Danube flood itself, which hydrologists explain mainly by saturated soils and several days of heavy rain.

Does Germany prohibit building in flood zones?

In principle, yes. Under §78 of the German Federal Water Act, erecting or extending buildings in officially designated flood zones is prohibited; the authority can grant an exception for an individual project only if it does not reduce flood retention, worsen flood levels or impair existing protection, and is built in a flood-adapted way. This differs from the more common U.S. approach of allowing construction if it meets elevation and floodproofing standards.

Is flood insurance mandatory in Germany?

Not as of this update. About 59% of German residential buildings had natural-hazard cover at the end of 2025 (41% in 2017), so roughly 41% still had none. In September 2026, the Federal Justice Minister presented key points under which every new residential building policy would include natural-hazard cover, without full compulsory insurance; a draft bill is expected in the first quarter of 2027.

What should U.S. property owners near rivers take away from Regensburg’s experience?

Three things: historic flood records can meaningfully understate future risk, especially as a warming climate makes heavy rainfall more likely; large-scale municipal flood infrastructure can take a decade or more to complete even with strong political will and funding; and flood insurance is never automatic under a standard homeowners policy, whether in Germany or the U.S. Building-level protection combined with adequate insurance remains the most reliable way to close the gap while public infrastructure catches up.

About the author

Josef Anhamm is Managing Director of anhamm Liquid Barrier Products GmbH, headquartered in Moers, Germany, with U.S. operations based in Webster, NY. This family-owned company has developed and manufactured mechanical retention systems for firewater, hazardous substances and floods for over 30 years, delivered to 40 countries.

This article was originally published in 2025 and fully updated and expanded in August 2026, then fact-checked and corrected in October 2026 against the official sources listed below.

Sources and further reading

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