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Flood protection measures in place to deal with snowmelt

Snow depths are significantly in the mountains are above normal and are likely to cause flooding in several places in Norway this summer. In order to handle the water from the snowmelt, Hydro is taking action and following the situation closely.

DSC_2820_2Åge Helge Botnen, Hydro000.jpg
(DSC_2820) Åge Helge Botnen, vedlikeholdsleder i Røldal-Suldal, på vei opp i fjellet på rutineoppdrag for å sjekke snømengde og tilstand i magasinene.

Record-high snow in the mountains in the south and north gives a high probability of spring flooding, writes varsom.no in a press release from May 20.

Rising temperatures across the country will cause snow melting to start in many places, with subsequent water flows in streams and rivers.

The snow melt is particularly late this year, which means that Hydro's areas are operating with snow amounts up to twice the size of this time of year.

Jan Helge Mårdalen, Hydro Power Generation Manager, says Hydro is monitoring the situation closely.

Jan Helge Mårdalen, leder for Kraftproduksjon i Hydro
Jan Helge Mårdalen, leder for Kraftproduksjon i Hydro

Has lowered the water level in the magazines

- We have 24-hour continuous flood risk monitoring and will help to avoid or mitigate flood damage. A flood will not normally cause damage to magazines, but the extent of damage in the rivers and communities below power plants can potentially be significant. We are now doing what we can to meet the water from the extensive amounts of snow that will melt, and have tapped our magazines, says Mårdalen.

(Inge Snømengde)  Inge Lynghamar, tekniker i Røldal-Suldal på oppdrag for å sikre linjenettet i reguleringsområdet.
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Flood expectations

The danger of flooding is particularly great in Western Norway, and it is likely that the water supply to the main reservoirs of Hydro in Røldal-Suldal and Fortun in the inner Sogn will overflow this summer.

- The fact that the water goes into overflow or through drainage ditches means that we release water outside the power plant to avoid an uncontrolled flood. According to our hydrologists, it is likely that there will be degrees of heat throughout the day over a thousand meters above sea level from the Pentecost weekend, which will result in a large increase in melting and inflow. However, in combination with dry weather, we expect a flood flow due to overflow to be moderate in the short term. But if the weather turns and we get sudden summer heat at the same time as heavy rainfall, the flow of water can be considerable. Such a situation increases the danger of flooding in our areas as well, says Mårdalen.

Inge Lynghamar, tekniker i Røldal-Suldal
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24/7 continuous monitoring and emergency response

Hydro works systematically on prevention and preparedness work to keep flood risk at the lowest possible level, and Mårdalen emphasizes that it is this continuous work throughout the year that becomes crucial in a flood situation.

- The most important thing to keep flood risk at the lowest possible level is the measures that are constantly on the move, such as clearing river beds for both forest and rock, plastering river banks and opening floodwaters to divert floodwater, and that we train personnel ahead of these, the floods were waiting.

At Hydro's power plants in Telemark, Røldal-Suldal, Sogn and Vennesla, Hydro is practicing flood preparedness throughout the year.

- It is crucial that we are able to reach out to employees who are well prepared for a flood situation, and that we have in place guard systems with competent operators and managers standing around the clock. We know we have employees who show a great will and sense of responsibility to comply with hatch regulations and clean up power plant intake when the company and society need it and who can stand until the situation is clarified, says Mårdalen.

Sammenligning av snøfall i 2019 mot 2020.
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Flooding at hydropower

Hydro is Norway's third largest operator of hydropower and operates 27 power plants in Telemark, Røldal-Suldal, Sogn, Vennesla and Skafså.

In a flood situation, watercourses developed for power generation will provide a better buffer than unregulated watercourses. Dams and the ability to transfer water between watercourses produce a flood-damaging effect by breaking up the amount of water that is fed to rivers.

The consequences of a flood can be further mitigated by tapping the magazines in advance of snow melting. The goal is to reduce the flow of water in the watercourse below the reservoir by allowing the dams to hold back floodwater and dampen the floodplain.

Røldal-Suldal, Valldalen dam og magasin.
Røldal-Suldal, Valldalen dam og magasin.

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