Lessons have been learned since floods hit Central Europe in 2002 and economic loss for 2013 is expected to be lower in the countries affected so far.
Germany, Austria and the Czech Republic have taken the brunt of the June 2013 flooding, with Poland, Hungary, Slovakia and Switzerland badly affected as well. Many parts of Germany have experienced serious flooding, including Saxony, Thuringia and Baden-Wὒrttemberg, and particularly the Bavarian city of Passau. Across the region 18 fatalities have been recorded with many people reported missing. In some areas flood defences, erected following the 2002 events, have protected some of the region’s valuable assets. It is expected that farmers will be some of the worst affected by the June floods.
Photograph of Passau, by kind permission of Twitter user, Sam Davies, @SamlDavies. Inset shows the flooded area ringed on JBA's 250-year river return period Europe Flood Map (c) JBA Risk Management Limited 2007-2012. (Background map Bing: (c) 2013 Microsoft Corporation and its data suppliers).
At this point in time, a realistic assessment of losses is not possible. Assessors are currently on the ground but the situation is changing daily. It is, however, unlikely that insured losses will equal those of the floods which hit the same region in 2002, due to the construction and improvement of flood defences since then. In 2002,economic losses were around 18 billion euros of which, 3.4 billion euros were insured losses.
Two thirds of German households in high flood risk areas are not insured against flooding but claims for other damages are expected to be high. Only limited flood coverage is available in some of the countries affected. In Austria, Spiegel online has made an initial estimate of the cost of flood damage at three billion euros, while the Czech Republic has set aside 200 million euros for clean-up operations and repairs.
Passau, sometimes called Dreiflüssestadt, after the three rivers at whose confluence it sits, has experienced its worst flooding in recorded history. A marker showing the worst flood on record in 1501 was submerged beneath the flood waters. Other cities throughout Germany’s river-rich landscape are also experiencing serious flood conditions. Settlements of all sizes along the Danube and the Elbe (whose normal summer level of about two metres rose to around 9 metres), are either flooded or threatened with flooding. The city of Dresden on the Elbe has damage running into tens of millions of euros. Chancellor Merkel has pledged 100 million euros of flood relief for the worst hit areas.
Flooding and landslides caused major problems in Austria. The flooding in Salzburg and the Tyrol was the worst since 2002. The swollen Danube has inundated several of Austria’s historic cities, while Austria’s meteorological service announced that two months’ worth of rain fell in just two days.
The Czech Republic
The Czech Republic’s prime minister has pledged £10 million in flood relief as flood warnings exist in forty cities. Flooding in Prague was serious but the city’s flood defences (erected following the floods of 2002) protected the old historic city centre. Melnik to the north of Prague, was reported to have been the worst-hit as it is positioned at the intersection of Vltava and Elbe rivers.
Switzerland and Hungary
Over the weekend, 31 May to 2 June, some 20 to 25cm of rain fell in Eastern Switzerland and numerous lakes and rivers caused floods, including the Rhine which burst its banks in Basel. Landslides in Switzerland have been causing disruptions to transport and mountain pass closures.
Downstream of flood stricken Deggendorf, the Danube in Western Hungary reached a depth of 9m which is 6m higher than normal. Volunteers have been working round the clock to defend their properties from the rising flood waters. Temporary dams are being constructed and the people in Budapest in the north west of the country near the Slovakian border are prepared to evacuate.
Slovakia and Poland
By Sunday 9 June much of the Slovakian capital, Bratislava, was under water. The Danube reached an all-time high of 10m on Wednesday 5 June. While a number of towns have been flooded, the new flood defences are expected to keep the worst of the flood waters at bay.
Poland was less seriously hit than other countries in the region but flood damage is still expected to run into the millions of euros.
Spring 2013 saw large amounts of snow fall and above average snow cover across many of the mountainous regions of Europe. Over the 30 days leading to 5 June, The Tropical Rainfall Measuring Mission (TRMM ) satellite data shows rainfall anomalies of up to 15mm per day over much of the Alpine region and Eastern Europe (see figure below). Coupled with snowmelt this led to wet antecedent conditions, and likely also to saturated ground.
During the last week of May, cold air moved south east crossing Western Europe and became slow moving over the Western Mediterranean. This drew warm air northwards from the Sahara, which created a strong temperature contrast and a southerly flow across the alpine region. The warm southerly flow over high ground led to a series of low pressure centres to the north of the Alps, which spiralled in an anticlockwise motion around Central Europe.
In the warm air mass close to the boundary of highly contrasting temperatures, strong convection was triggered, in turn leading to extensive areas of thunderstorms.
A split in the Jet Stream
The Austrian Met Service reported rainfall of up to 300mm between 30 May and 3 June, with many areas experiencing in excess of 75mm (see figure). These amounts of rain would usually be expected over a period of several months rather than days, with initial estimates of return periods of between 40 and 100 years.
Initially, the more mountainous areas with steep topography were amongst the worst areas affected. In these environments there is low infiltration capacity of soils, so intense rainfall is rapidly translated into runoff. This is then funnelled into narrow valleys which can have devastating impacts. The split in the jet stream, with one branch over Scandinavia and another across North Africa, resulted in the low pressure area being maintained in Central Europe for several days, bringing continued rainfall and further stressing river catchments.
As further data is collected and assessed, comparison with historic events will become easier. Initial comparisons are likely to be with the floods of Elbe and Danube in August 2002; due to prolonged heavy rain, these had approximately a 1 in 100-year return period.
Extract from JBA’s modelled footprint of the event.