Flood damage in Carinthia, Slovenia, 09 August 2023. Photo credit: Slovenia Red Cross
Flood damage in Carinthia, Slovenia, 09 August 2023. Photo credit: Slovenia Red Cross

by Richard Davies, floodlist

In early August 2023, Slovenia was gripped by a catastrophic weather event that unleashed heavy rain, severe flooding and landslides across several regions of the country. The disaster, considered the largest in the nation's history, had far-reaching and devastating consequences for approximately two-thirds of the country's territory.

Floods in the Municipality of Laško, Savinja Region, Slovenia, 06 August 2023. Photo credit: Slovenia Red Cross
Floods in the Municipality of Laško, Savinja Region, Slovenia, 06 August 2023. Photo credit: Slovenia Red Cross

Relentless rainfall fell across the country from 03 to 06 August. According to a report from the Slovenian Environment Agency (ARSO) the typical amount of precipitation for the whole of August fell in just a few hours at some stations. Record or near-record daily rainfall totals were measured at several sites on 04 August.

72-hour precipitation amount from 03 August to 06 August, measured by automatic weather. Image: ARSO
72-hour precipitation amount from 03 August to 06 August, measured by automatic weather. Image: ARSO

ARSO reported extensive flooding along the Drava, Savinja, Kamniška Bistrica, Sora, Sava, Mura, and Ljubljanica river basins. High water thresholds were exceeded at 122 gauging stations on 74 rivers. Record discharges were measured at 31 gauging stations, a majority of them reaching 100 or higher return period.

Exceeded high water discharge or water stage thresholds at the gauging stations in Slovenia during the flood event between 04 and 08 August 2023. Image: ARSO
Exceeded high water discharge or water stage thresholds at the gauging stations in Slovenia during the flood event between 04 and 08 August 2023. Image: ARSO
Temporal review of the flooding conditions in Slovenia between 09 and 09 August by affected region or river basin at 12-hour intervals. Image: ARSO
Temporal review of the flooding conditions in Slovenia between 09 and 09 August by affected region or river basin at 12-hour intervals. Image: ARSO

The resulting flooding and landslides rendered areas completely inaccessible, and caused massive damage to buildings and infrastructure. The scale of the disaster is unprecedented in Slovenia's history, with approximately two-thirds of the country's territory affected.

In a report on 17 August, the International Federation of Red Cross And Red Crescent Societies (IFRC) reported 400 buildings destroyed, 8,000 people evacuated, 1,500,000 people affected, 6 fatalities, 30km of roads damaged, 70 bridges destroyed or severely damaged, and 750 hectares of land flooded. According to IFRC, the Upper Carniola, Central Slovenia, Koroška, and Savinjska regions were the hardest hit.

Map of areas impacted by floods in Slovenia. Image: IFRC
Map of areas impacted by floods in Slovenia. Image: IFRC

Copernicus EMS Rapid Mapping was activated on 04 August.