Experts looking for solutions for landslides caused by 2023 floods

Some landslides that triggered after last year's floods are so complex to tackle that they are beyond the scope of the municipality, said head of the state technical office Blaž Dolinšek said on Friday, when government representatives visited some of the areas hit by the floods.

The technical office founded a special landslide task force, composed of geotechnics, geologists, hydrologists and other experts.

"When we say that we need to give water some space, that applies to landslides too," said Dolinšek.

"If something is urgent and if the landslide is threatening something, we have to prevent it. But the decision to take concrete measures is very long as the landslide has to be studied in detail and several options have to be prepared," he said.

"This is normal for landslides of such scale," he said to explain why some landslides have not seen much work done in the last year.

One such example is a landslide in the municipality of Kamnik, north, which was triggered by the August floods. The state technical office started monitoring the landslide closely in October when more heavy rain was expected.

"When we visited the site, it became apparent that the bottom part of the landslide moved by around 250 metres in two months," said geologist Jaka Rupnik. They set up an alarm system which remains in place.

"The situation is very complex and we treat it as such," said Rupnik. Geological and geo-mechanical analyses of the landslide will begin soon and the Water Agency is leading a project to manage the torrential watercourses and the lower course of the Bistričica River, he said.

"When it comes to actual reconstruction, I believe it will start next year. If part of the project documentation is completed this year, that will be the first success," said Rupnik.

In addition to geotechnical measures on landslides, works will be focused on torrential waters and stabilisation of riverbeds, said hydro technician Jošt Sodnik. "In the future these measures will have to be carried out upstream to mitigate the situation and ensure some safety downstream," he said.

Last year's floods pointed to the issue of landslide management at the national level. "If a landslide blocks a road, it is the job of road workers, if it covers a watercourse, it is the job of water workers," said Lidija Kegljevič Zagorc, state secretary at the Natural Resources Ministry, adding that depending on the size, the landslide is tackled by either the municipality or the state.

The state will address the issue of landslides more systematically in the future, she said, adding that landslide management investment will be handled by the Water Agency and the Water Directorate at the Natural Resources Ministry.

Kegljevič Zagorc also believes that a landslide strategy is needed to determine how to live with them and how to adjust spatial planning to them.

Geological Survey of Slovenia estimates that around 10,000 landslides triggered because of the August 2023 floods, which is the most landslides recorded to be caused by a single weather event.