Unusually heavy rainfall in Austria: Danube power plants are preparing for flooding

Due to the expected heavy rainfall in the coming days, all power plants on the Danube are staffed in shift operation: “Everyone who is available is assigned,” it says. If the exceptional flood actually occurs, the sluices of the power plants would have to be opened for the first time since 2013.

In addition to fire brigades and other emergency services, the energy provider and power plant operator Verbund is also preparing for the predicted heavy rainfall in the coming days: Normally, the operation of the nine Verbund hydroelectric power plants on the Danube is remotely controlled, but from Friday all power plants will be staffed with personnel to respond to heavy rainfall and possible flooding, and to carry out repairs. The Verbund has around 350 employees in Upper and Lower Austria: all who are not on sick leave or on vacation are on shift work – on duty on the weekend, as Verbund spokesman Florian Seidl told the “Presse”. “Everyone who is available is assigned.”

Whether the Danube will actually lead to flooding (and if so, to what extent) is of course still unclear, but a rise in the water level is to be expected. The Danube is already a very water-rich river in its normal state, 3000 cubic meters per second flow in Lower Austria, “that’s three million liters of water per second, that’s an enormous amount”. In addition, there are “no reservoirs, no retention basins” on the Danube. The Verbund team is on standby from 5000 cubic meters per second, as on the coming weekend, and there are clear plans on how to proceed.

“As if the power plant didn’t exist”

But what happens in the hydroelectric power plants when the Danube carries too much water due to the rainfall? First, “we open the weir fields”, via these flaps on the power plant “we can regulate the water very well”. However, if that is not enough, “we open the locks”, there is only “open” or “closed”, ie the masses of water are completely passed through. “At some point, so much water flows through as if the power plant didn’t exist.”

The opening of the locks only happens in absolute exceptional situations, most recently during the century flood in 2013 and before that in 2002 and 1991.

Too much water in the Danube not only leads to an increased risk of flooding and possible flooding, it also reduces the amount of electricity that can be generated in the power plant. “At some point, the water level below the power plant rises so much that there is no longer sufficient drop in height to drive the turbines,” says Seidl. Because in order to generate electricity, a water gradient of eight to ten meters is required. So if there is too much water under the power plant, little or no electricity can be generated.

If this happens over the weekend, however, there is still no need to expect power outages: the Verbund has pumped storage power plants in the west and the Mellach gas-fired power plant in the east for these cases. The Ottenstein reservoir in the Waldviertel, on the other hand, is being drained as a precaution in the course of Thursday – a preventive measure to get enough free space in the reservoir. Reservoirs are being lowered

The Verbund is also preparing for the predicted heavy rainfall in Carinthia: On Wednesday, the water levels of the three large reservoirs on the Drau in Carinthia began to be lowered. The reservoirs near Rosegg, Feistritz and Völkermarkt are affected.

The levels are now being slowly lowered by one meter each – according to the current forecasts, however, the Verbund assumes that the Völkermarkt reservoir, which is regulated at the Edling power plant, will even have to be lowered by one and a half meters.

Villach closes paths along the Drau

The city of Villach is also taking precautions because of the weather warnings, as reported by the Austria Presse Agentur.

From Thursday, 1:00 p.m., the Draubermen – i.e. the pedestrian and cyclist area along the Drau – will be closed for safety reasons. The area between the power plant and Silbersee is affected by the closure on both sides. The paths on the Gail will also be closed for pedestrians and cyclists, namely in the area between Gödersdorf and Schütt.