Gauteng and NW Province

2013 European floods

From Wikipedia, the free encyclopedia.

Ongoing flooding in Central Europe began after several days of heavy rain in late May and early June 2013. Flooding and damages have primarily affected south and east German states, western regions of the Czech Republic, and Austria. Switzerland, Slovakia, Belarus, Poland, and Hungary have been affected to a lesser extent.The flood crest then progressed down the Elbe and Danube drainage basins and tributaries, leading to high water and flooding along their banks.

Meteorological history
The spring weather preceding the flooding had been wet in the region, and May 2013 had been one of the three wettest in the last 156 years in Austria, together with the years 1962 and 1965. Austria saw twice as much rainfall as average during the month,resulting in the ground in the region becoming saturated. Soils in Germany were showing record levels of moisture prior to the rains.The already saturated soils led to greater runoff when the rains began.

In last ten days of May a low pressure system named “Christoffer” swung up from the Mediterranean across the Black Sea then across Ukraine and Poland to Northern Germany, eventually bringing a very moist, and warm airmass to Central Europe from north-east. Late May saw a blocking high “Sabine” located over the Sole sea area to the west of the UK and France. This split the jet stream over Europe which maintained the weather pattern in Central Europe.

Spring and summer flooding in Central Europe is commonly associated with the so-called “Zugstrasse Vb” track of low pressure areas, which bring low pressure and moist air from the Mediterranean Sea over Central Europe, and have led to severe flooding in the affected region before. Low pressure areas “Frederik” and “Günther” formed over the northern Adriatic and tracked north towards central Europe. The high pressure “Sabine” and low pressure areas brought an airflow from the north across Germany, which brought the water-laden air from the north east. The air mass was pushed to the south by the northerly flow where it was lifted as it moved south from the North European Plain over the Thuringian Forest, Ore Mountains, and Bohemian Forest. The air was then lifted along the north side of the Alps in Austria as the air masses were pushed into the Alps by the northerly flow, which led to intense orographic precipitation. Heavy rain was reported in the Austrian states of Vorarlberg and Tyrol and the area of Salzburg, and to the mountains of Upper Austria and Lower Austria and Upper Styria in a short time.

On 30 May to 1 June, 150 to 200 mm of rain fell, in places reaching around 250 mm, which in just a few days was the equivalent normally seen over two and a half months on average. The rainfall experienced in Austria has an expected return period of between 30–70 years. The bulk of the rain fell in only two days in Salzburg, Tyrol, and Vorarlberg, which is thought to have a return period of more than 100 years.

The flood waters are expected to exceed the levels seen during the disastrous “once in a century” Central European floods of 2002 in some areas.

Climatological context
Stefan Rahmstorf, a professor of ocean physics at the Potsdam Institute for Climate Impact Research, stated that a low-pressure system that dumped the rain was locked into place by a disturbance with the global wind pattern. Linking the weather to the concurrent drought conditions in Russia, he said pressure systems stay locked in place, causing a persistent pattern of weather in an area. He also stated that this planetary wave resonance is not a local effect but spread around the whole (northern) hemisphere. When a “resonance” episode occurs, half a dozen peaks and troughs of high or low pressure form around the hemisphere. This explains why some parts of the world become unseasonably hot or cold and others unusually dry or rainy. The resonance theory has become widely discussed among climate scientists since first published in the scientific journal Nature Climate Change last year. But it has met resistance among experts who are wary about associating single extreme-weather events with climate change.
2 June 2013

Whether or not you believe in climate change or global warming, water conservation is a real concern. Using less water is each and everyone’s responsibility. Harvest rainwater and use it at a later stage. Drought and floods seem to be walking hand in hand these days; take from the one and give to the other.

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