08 November 2012

Record discharge measured on the Drava!

The record discharge on the Drava was surpassed today. At the city of Ptuj they measured 3100-3200 m³ per second, which surpassed by 500 m³ the highest ever measured value of 1965. To compare this data, the Danube's discharge at Budapest was 1760 recently. Within days they can observe at the mouth of the river a rare hydrologic phenomenon, when the fourth largest tributary of the Danube will deliver twice as much water as the main river.
Lavamünd under water, 06. 11. 2012. (photo: Standard.at)
Due to the rainy weeks, the Drava overflowed its banks. The 80-100 mm of rain fallen at the Slovenian-Italian-Austrian border started floods along the Isonzo, the Mura, the Sava and the Raba. On the latter a serious flood has just went down, if not the same amount as on the Drava. At Szentgotthárd the water level was only 80 cms below the hitherto measured maximum.
The worst situation was formed on the Austrian and Slovenian sections of the Drava’s water system. All the 16 hydropower stations (11 Austrian, 8 Slovenian and 3 Croatian) were stopped along the entire length of the river. In Austria they were force to open reservoirs of dams in order to protect the barrages. As a consequence, the settlement of Dravograd was completely encircled by the swollen river and the landslides. The students were not allowed back home from the schools, as they already had nowhere to go. The residents were accommodated in hotels. Gas supply was interrupted and central heating was shut down.

Dravograd under water, 06. 11. 2012. (photo: Poleshift.ning.com)

The settlement of Duplek was almost entirely flooded by the Drava. Here about 250 to 300 houses stand in the water. They have measured a record water output even on the Suhadolnica (~Dry Valley) creek. From several farms they had to evacuate the animals to higher grounds. Fire brigades and 120 soldiers of the Slovenian Army participate in the emergency measures.

The flood has already went down at the Austrian settlement of Lavamünd at the Slovenian border. Now they are cleaning up the ruins and debris. Several bridges were damaged, roads washed under by the flooded tributaries. It is still raining at the upper reaches of the Drava, so the professionals of hydrography still expect high water during the night. The long-term mean discharge of 300 m³/sec at Maribor has swollen tenfold, and most Slovenian water scales have shown values above 8 meters during the day.

 The creek of Waidis overflowing its banks (photo: Krone.at)

Currently the flood peaks at the Croatian section and is nearing towards the Hungarian border, Őrtilos where the water level has been rising fast since yesterday morning. According to the forecasts, the water level record will be surpassed also here. Probably they will order the highest level of flood preparedness on the Hungarian section as well.

Meanwhile, the water level of the Danube and Lake Balaton is extremely low. Thus at the confluence of the Drava and the Danube the two masses of water will not become congested as the last time in 1965, during the great flood.

The Drava everywhere (photo: Sloveniatimes.com)
In 1965 the flood peaking at 2600 m³ caused a far greater devastation, since the vast majority of the anti-flood banks were built only after this. This flood was also particularly memorable, because it arrived at the same time with the hitherto most enduring Danube flood, when the flood alarm was in effect for more than 100 days.

The flood of the Drava in Austria, 1965 (photo: Dravaradio.eu)
The flood of November 2012 arrived in a rather unusual period in Slovenia. The late autumn period is typically a time of low water, when the high mountain streams usually dry up, mainly due to freezing, and the melting of the glaciers is terminated. Now, however, due to the several days of continuous raining, the soil has been so saturated with water that it was unable to absorb it all. This is indicateby the news about landslides and mud floods. Autumn and winter rains are not uncommon in the Mediterranean. However, if it is true that this climate is slowly advancing to the north, we must prepare for even greater floods.

Therefore the term “the greatest flood of the century” - nowdays commonly used by the media - must be strongly avoided, since less than 12 years have passed from the 21st century.

Translation by: Tamás Sajó

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