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Slovenia

River floods

Slovenia: Vulnerabilities

Extreme floods occurred from 4 to 6 August 2023 in Slovenia causing three casualties and total direct and indirect damage, including post-disaster needs, close to EUR 10 billion. This was significant at over 10 % of Slovenia’s annual gross domestic product. The return period of the event (both rainfall and peak discharge values) was in many locations in Slovenia over 250 or even over 500 years. In a network of 26 meteorological stations, 12 h rainfall intensity was higher than 100 mm at 13 stations (26).

The last decade has seen a number of large-scale floods. It has been estimated that floods in the Savinja river basin have caused damage amounting to 20% of Slovenia’s national income. The values of the peaks of maximum flows of the majority of watercourses have grown (21).


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Europe: casualties in the past

The annual number of reported flood disasters in Europe increased considerably in 1973-2002 (1). A disaster was defined here as causing the death of at least ten people, or affecting seriously at least 100 people, or requiring immediate emergency assistance. The total number of reported victims was 2626 during the whole period, the most deadly floods occurred in Spain in 1973 (272 victims), in Italy in 1998 (147 victims) and in Russia in 1993 (125 victims) (2).


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Europe: flood losses in the past

The reported damages also increased. Three countries had damages in excess of €10 billion (Italy, Spain, Germany), three in excess of 5 billion (United Kingdom, Poland, France) (2).


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Europe: flood frequency trends in the past

In 2012 the IPCC concluded that there is limited to medium evidence available to assess climate-driven observed changes in the magnitude and frequency of floods at a regional scale because the available instrumental records of floods at gauge stations are limited in space and time, and because of confounding effects of changes in land use and engineering. Furthermore, there is low agreement in this evidence, and thus overall low confidence at the global scale regarding even the sign of these changes. There is low confidence (due to limited evidence) that anthropogenic climate change has affected the magnitude or frequency of floods, though it has detectably influenced several components of the hydrological cycle such as precipitation and snowmelt (medium confidence to high confidence), which may impact flood trends (24).

Despite the considerable rise in the number of reported major flood events and economic losses caused by floods in Europe over recent decades, no significant general climate‑related trend in extreme high river flows that induce floods has yet been detected (7).


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Europe: projections for the future

IPCC conclusions

In 2012 the IPCC concluded that considerable uncertainty remains in the projections of flood changes, especially regarding their magnitude and frequency. They concluded, therefore, that there is low confidence (due to limited evidence) in future changes in flood magnitude and frequency derived from river discharge simulations. Projected precipitation and temperature changes imply possible changes in floods, although overall there is low confidence in projections of changes in fluvial floods. Confidence is low due to limited evidence and because the causes of regional changes are complex, although there are exceptions to this statement. There is medium confidence (based on physical reasoning) that projected increases in heavy rainfall would contribute to increases in rain-generated local flooding, in some catchments or regions. Earlier spring peak flows in snowmelt- and glacier-fed rivers are very likely, but there is low confidence in their projected magnitude (24).

More frequent flash floods

Although there is as yet no proof that the extreme flood events of recent years are a direct consequence of climate change, they may give an indication of what can be expected: the frequency and intensity of floods in large parts of Europe is projected to increase (14). In particular, flash and urban floods, triggered by local intense precipitation events, are likely to be more frequent throughout Europe (15).


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Adaptation strategies - Spatial planning

Climate change will bring about a potentially increased risk of flooding. The risk of flooding in Slovenia is already high. Apart from systematic implementation of hydro-technical measures, it will be important to downgrade the penetration of settlements in regions at flood risk, as the costs of technical protection against floods may grow substantially, while exacerbating problems downstream. All this will require more robust planning of specific infrastructural facilities, particularly bridges and road and rail connections. Room must be preserved for inundation areas and high water catchment areas (21).

The expected reduced low flows must be taken into account in the design of the dimensions of wastewater treatment plants and plans for capturing water for industrial needs and irrigation (21).

Adaptation strategies - Contingency planning

Torrential floods represent a particularly serious problem in Slovenia; these emerge in the upper parts of river basins. These situations are characterised by a lack of time for the preparation and implementation of measures, and for the possible evacuation of goods and people. As a consequence, the damage and risk to human life are substantially greater. In order to address this problem successfully, plans have been drawn up for the early warning system to be upgraded. This system is based on meteorological prognostic models with high spatial resolution linked with hydrological models, which makes it possible for the responsible services to engage promptly in a state of increased readiness. To this end, the real-time monitoring of rainfall enabled by meteorological stations and radars can serve as a basis for the implementation of measures (21).

Adaptation strategies - EU Directive on flood risk management

The new EU Directive on flood risk management, which entered into force in November 2006, introduces new instruments to manage risks from flooding, and is thus highly relevant in the context of adaptation to climate change impacts. The Directive introduces a three-step approach (2):

  • Member States have to undertake a preliminary assessment of flood risk in river basins and coastal zones.
  • Where significant risk is identified, flood hazard maps and flood risk maps have to be developed.
  • Flood risk management plans must be developed for these zones. These plans have to include measures that will reduce the potential adverse consequences of flooding for human health, the environment cultural heritage and economic activity, and they should focus on prevention, protection and preparedness.

References

The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Slovenia.

  1. Hoyois and Guha-Sapir (2003), In: Anderson (ed.) (2007)
  2. Anderson (ed.) (2007)
  3. Mitchell (2003)
  4. Barredo (2009)
  5. Höppe and Pielke Jr. (2006); Schiermeier (2006), both in: Barredo (2009)
  6. Höppe and Pielke Jr. (2006), in: Barredo (2009)
  7. Becker and Grunewald (2003); Glaser and Stangl (2003); Mudelsee et al.(2003); Kundzewicz et al.(2005); Pinter et al.(2006); Hisdal et al.(2007); Macklin and Rumsby (2007), all in: EEA, JRC and WHO (2008)
  8. EEA, JRC and WHO (2008)
  9. Wang et al.(2005), in: EEA, JRC and WHO (2008)
  10. Milly et al. (2005), in: EEA, JRC and WHO (2008)
  11. Hisdal et al. (2007), in: EEA, JRC and WHO (2008)
  12. Ramos and Reis (2002), in: EEA, JRC and WHO (2008)
  13. Barnolas and Llasat (2007), in: EEA, JRC and WHO (2008)
  14. Lehner et al.(2006); Dankers and Feyen (2008b), both in: EEA, JRC and WHO (2008)
  15. Christensen and Christensen (2003); Kundzewicz et al.(2006), both in: EEA, JRC and WHO (2008)
  16. Palmer and Räisänen (2002), in: EEA, JRC and WHO (2008)
  17. Kay et al. (2006); Dankers and Feyen (2008), in: EEA, JRC and WHO (2008)
  18. Andréasson, et al. (2004); Jasper et al.(2004); Barnett et al.(2005), all in: EEA (2009)
  19. Arnell (2004); Milly et al. (2005); Alcamo et al. (2007); Environment Agency (2008a), all in: EEA (2009)
  20. Dankers and Feyen (2008), in: EEA (2009)
  21. Republic of Slovenia, Ministry of the Environment, Spatial Planning and Energy (2002)
  22. Ciscar et al. (2009), in: Behrens et al. (2010)
  23. Kundzewicz (2006)
  24. IPCC (2012)
  25. Janža (2013)
  26. Bezak et al. (2023)

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