Slovenia's Flood Forecasting Success: Minimizing Casualties Through Effective Warning Systems

News & Media
Areal picture of a flooded area in Slovenia
Flooding in Slovenia, summer 2023

In the wake of what has been declared the nation's 'worst-ever natural disaster,’ more than 70% of Slovenia's territory, predominantly situated in the Danube River Basin, has been severely affected by extreme flooding. The scale of this catastrophe has led to billions of Euros in damages and a tragic loss of lives.

Thanks to the efficient response of Slovenia's flood early warning system, manned by a dedicated team, human casualties could drastically be minimized. Despite the vast territorial expanse affected by the floods, their devastating force, and the substantial volume of stormwater, the loss of life has been kept remarkably low, with a reported count of six individuals.

The sheer magnitude of the flooding has prompted comparisons to a 'worst-ever natural disaster,’ an assertion reinforced by the issuance of a red warning by the Slovenian Environment Agency (ARSO) issued a red weather alert on 4 August. Currently, a coordinated effort is underway to reach the inundated regions and initiate clean-up operations. The combined efforts of rescue teams and volunteers are aimed at providing assistance to affected communities, assessing the damage, and eventually restoring normalcy in the affected areas.

Slovenia's resilience was tested as the nation mobilized its resources and expertise to combat the aftermath of this unprecedented natural disaster. As the recovery process begins, the government, local authorities, and citizens are uniting with the civil defense forces to rebuild what has been lost and emerge stronger in the face of adversity. 

How the Floods Warning System Operates in the Danube River Basin
The respective legislation of each Danube state governs activities associated with protection against floods. Flood protection authorities and Emergency authorities in the Danube countries are bodies of the state, regional or municipal administration fully responsible in pertinent areas for the organization of flood monitoring services. These authorities coordinate and control the activities of other participants involved in flood protection. 

Typically, the individual states of emergency depend on the water levels or discharges, which are defined for each section of the river according to local/national flood risk and emergency management plans. The state of alert generally occurs when the water level rises above the river channel. The status of danger, emergency, or severe situation is proclaimed at the behest of the competent river basin authority with reference to the hydrological forecast. 

In the event of floods, the meteorological services of the Danube countries are tasked with forecasting activities that include monitoring and forecasting the weather situation and advisory and warnings on dangerous weather events such as heavy precipitation, storms, and hail. Quantitative precipitation forecast belongs to the most important activities of the meteorological services and is provided through numerical weather modelling by the top European Meteorological Services (France, Germany, and UK). This information is supplemented by data from the meteorological satellites and maps of rain intensities provided by national meteorological radars.

The hydrological services monitor the present situation of rivers within the Danube River Basin through a network of gauging stations that provide regular hydrological information complemented by data from the River Basin Authorities. The range of hydrological information encompasses vital aspects, including data on flow regulation within reservoirs, a factor that significantly impacts the progression of floods.

How to Access Flood Forecasting Data
Flood forecasting services regularly provide hydrological forecasts to the Danube River Basin Authorities and other stakeholders and share these projections on dedicated websites. In times of flooding, these services promptly inform flood protection authorities and other involved participants on the evolving flood risks and the evolution of the flood. Warning messages are swiftly distributed as soon as extreme meteorological or hydrological conditions have been forecasted. During flood events, these alerts include information about the flood’s progression and further trajectory.

A Europe-wide system: the European Flood Awareness System (EFAS)
In the aftermath of the 2022 Danube and Elbe floods, the European Commission launched the European Flood Awareness System (EFAS), aimed at enhancing  flood preparedness across Europe. Europe. Developed in close collaboration with the ICPDR and the national hydro-meteorological services sharing the Danube River Basin, amongst others, EFAS seeks to gain time for preparedness measures ahead of major flood events, particularly for large trans-national river basins such as the Danube, both on national as well as European level. This is achieved by providing complementary, value-added information to national hydrological services and ensuring that the European Response and Coordination Centre remains informed about ongoing floods and the possibility of upcoming floods across Europe. Since 2012 EFAS has been fully operational as part of the Copernicus Emergency Management Service. EFAS provides the national authorities with a wide range of flood forecast information, such as medium-range flood forecasts with 10-15 days lead time, impact forecasts, flash flood forecasts with up to 48 hours lead time, and seasonal outlooks for the coming months. The information can be accessed by the EFAS partners either through a password-protected website or through web services. All relevant flood forecasting authorities in the Danube River basin are EFAS partners.

EFAS is constantly being further developed with regular new model calibrations, including more in-situ data or changes to the model setup and improving its products. Through collaboration at the Danube River basin and at the European scale, EFAS fosters knowledge exchange and data sharing amongst the national hydro-meteorological authorities and hence is an essential tool to improve overall flood risk management in the Danube River Basin. see:

Enhancing Flood Preparedness: The Danube Hydrological Information System (DanubeHIS) 
The ICPDR has recently been developing the Danube Hydrological Information System (Danube HIS). The DanubeHIS is a comprehensive platform presenting crucial data on parameters such as water level, discharge, temperature, and precipitation. The participating countries contribute data voluntarily, depending on their data availability. The data shown is specifically focused on the Danube and its major tributaries. The primary objective of the DanubeHIS is to provide basic hydrological and meteorological near real-time data in a standard format across the entire Danube River Basin. Additionally, validated long-term data series for flood risk management or any water-related scientific activities in DRB are included, if possible. 

The DanubeHIS covers the entirety of the Danube River Basin and greatly benefits from a strong collaboration with the Sava Commission, utilizing vital data sourced from the subregional Sava HIS. Following the impactful 2014 floods in the Sava River Basin, the Sava Flood Forecasting and Warning System was established, emerging as one of the most advanced systems of its kind tailored to a sub-basin. This system remains consistently updated to enhance its effectiveness.

This interplay between these distinct platforms serves as a testament to our commitment to optimizing efficiency not only on a transboundary scale but also at the sub-basin level when confronting the challenges posed by floods.

Source and Editorial: ICPDR