Toolbox for transboundary water contingency management in the Sava River Basin

The Sava River Basin in Southeastern Europe covers nearly 100 000 km 2 (i.e., 12% of the larger Danube River Basin to which it is part) and stretches over 6 countries, i.e., Albania, Bosnia and Herzegovina, Croatia, Montenegro, Serbia, and Slovenia. The watershed includes rural areas as well as many large cities (such as Belgrade, Ljubljana, Sarajevo, and Zagreb) and hosts a population of around 9 million people. The basin and its population are threatened by increasingly frequent extreme weather and flooding events, putting human safety and livelihoods at risk. Heavy precipitation and catastrophic flooding in the spring of 2014 caused 79 deaths and affected more than 2.5 million people through property damage, economic losses, and evacuations. The damage was estimated at EUR 3.8 billion ( ICPDR and ISRBC, 2015 ). Also, pollution run-off from flooding in the Sava River Basin poses a significant threat to both the environment and to human health. Floodwaters carry a mix of sediment, debris, nutrients, and chemicals from agricultural lands, including slurry and pesticides, contaminating waterways with sediments. Moreover, structural damage to infrastructure within the watershed and recovery activities after floods can release hazardous substances into rivers [1] . This endangers the environment as well as people. Ingestion of pathogens or heavy metals from contaminated water or food sources increases the risk of health hazards, such as gastrointestinal diseases and, in the long-term, cardiovascular disorders, cancer, diabetes, and kidney damage ( Rehman et al., 2017 ). South-Eastern Europe is highly vulnerable to climate change induced flooding. A projected increase in precipitation is expected to further intensify flood hazards in Eastern Europe ( Bednar-Friedl et al., 2022 ), with 13% higher flood peaks projected in 2011-2040 as compared to present day (1990-2013), and 23% higher peaks in 2071-2100 ( De Roo et al., 2016 ). Increased flood risk is expected to be greatest in the upper part of the basin, and in the main tributaries, i.e., the rivers Kupa, Una, and Bosna ( De Roo et al., 2016 ). In addition, socioeconomic factors in the Sava River Basin, such as the 2007 financial crisis and high rural-to-urban migration, have resulted in an aging population, inadequate water management infrastructure and a lack of ‘climate-proof’ housing, leaving the population vulnerable ( UNESCO, 2023 ; World Bank, 2015 ). [1] such as seen after the 2014 floods due to slurry release by the damaged Stolice antimony mine in the Kostajnik stream and due to water pumping from the flooded Tamnava-Zapadno polje coal mine into the Kolubara river ( Republic of Serbia, 2014 )

The objective of the implementation of the water contingency management (WACOM) tools, within the Framework Agreement on the Sava River Basin (FASBR), is the improvement of transboundary collaboration across the Sava River Basin and its governance systems, in order to reduce the risks to the environment and public health associated with flooding and accidental pollution. Specific objectives include: To cope with floodings and accidental pollution at the source of the issues rather than further downstream in another jurisdiction; To improve information exchange and coordination of upstream and downstream flood and pollution response mechanisms and as such improve their efficiency and effectiveness; To connect countries and sectors involved in water-related disaster management, water management, and navigation; To identify and involve key target actors to increase awareness and improve the protection of waterways, flood prone zones, infrastructure, livelihoods and human health.

The International Sava River Basin Commission ( ISRBC ) facilitated, as part of its Framework Agreement on the Sava River Basin ( FASRB ), the development and implementation of a solution toolbox to support transboundary cooperation on water resource management. The toolbox of solutions addresses three components key to water contingency management, i.e., situational awareness, communication, and forecasting. The toolbox acknowledges the diversity in potential responses to water disasters and in the actors involved, and includes (i) a real-time knowledge sharing platform to coordinate the response to transboundary accidents, (ii) a GIS-based model of the entire river basin showing real-time and hypothetical flooding and pollution, and (iii) a best practices catalogue for use of the developed set of tools in disaster management: The transnational incident coordination tool [1] is an online, centralised reporting system, enabling real-time, efficient and effective communication and knowledge sharing between stakeholders. The system enables stakeholders involved in mitigating a transboundary flood or pollution incident to document all personnel assignments and actions in a single database. The tool follows the Incident Command System standards for crisis management developed as part of the USA’s National Incident Management System ( ICS/NIMS ). In case of an event, stakeholders submit activity reports to a database that integrates all information on the incident, i.e., all ‘ activated headquarters ’ and people involved in the disaster response, contact numbers, and which actions they take. The transnational situational awareness tool integrates dynamic information from different government levels and authorities that are responsible for managing a flood or pollution event. This tool supplements the transnational incident coordination tool with additional background information and a snapshot of significant incidents. Authorities supply information about an event via a common reporting template to inform on different measures taken and to identify actions that require transnational coordination. The transnational modelling tool is a GIS-based mapping tool [2] designed to assist emergency management in the area of the Sava River and many of its major tributaries. The tool can predict, for example, pollution distribution based on actual discharges in the Sava River. The prediction model can display how long an oil spill will take to reach downstream areas until up to over a month in advance, depending on the location and water flow. This facilitates planning by civil protection authorities and enables them to plan and intervene at the earliest stage possible. The best practices catalogue contains almost 100 guidelines on the use of the tools (i and ii). Two strategies, one for flood responses and one for accidental pollution responses, accompany the guidelines. They outline the rationale for implementing the proposed toolbox and the different procedures related to coordination, modelling, and situational awareness. The catalogue was compiled and verified by experts in water management and civil protection as well as stakeholders involved in risk management in the Sava River Basin. The large cooperation framework of the ISRBC, which’ foundations were already laid in 2002, facilitated international collaboration to design, deliver and implement the toolbox. The WACOM Interreg project within the Danube area Transnational cooperation Programme 2021-2027 enabled the development of the tools. [1] Early 2024, the procedural framework for the use of the incident coordination tool was still under adoption by the working bodies of the ISRBC. [2] The model is partially based on the pre-existing SAVA GIS tool from the International Sava River Basin Commission (ISRBC) and the Sava Flood Forecasting Warning System (FFWS)

The role of the toolbox and its implementation strategy in improving resilience and protecting people and the environment from flooding and pollution was tested during the 2023 floods in Slovenia. Agencies and stakeholders who had been involved in the evaluation of the toolbox and knew how to apply it, successfully used the tools for flood preparedness response activities, and confirmed their functionality and value. Still, a wider implementation could further improve communication between several headquarters and the efficiency and effectiveness of actions. The toolbox development cost was just over EUR 2.9 million. The costs were funded by the Interreg Danube Transnational Programme , co-financed by other EU funds, as part of the WACOM project . Further spending is needed for maintenance of the prediction model (2 person-months per year with every 5 years an additional 6 months for substantial ICT upgrades); day-to-day management and maintenance of the coordination tool by an administrator; and training of the authorities who will use the tools (half a day per (online) training session).

The success of the toolbox in preventing societal and environmental impacts from flooding and pollution events is driven by the international collaboration between many stakeholders committed to a common risk management approach. Strong stakeholder involvement, facilitated by the existence of an established, large collaboration framework, i.e., the International Save River Basin Commission ( ISRBC ), ensured a shared, clear vision for the tool, its inputs and its implementation steps, which contributed to its success. Since 2023, successful implementation of the tools and strategies is being monitored annually via indicators that describe the status and progress in flood and pollution risk reduction in 14 key areas of intervention [1] . Barriers include the transboundary usage of the toolbox, which involves stakeholders from several Sava River Basin countries, who speak different languages and have different national backgrounds. The final products and tools are developed in English, which may create a barrier for uptake in a national context where stakeholders speak a different language. Further, the shift from existing national procedures for incident management to a common, transnational framework posed challenges to some national stakeholders. For example, during the severe flood event in Slovenia in August 2023, an estimated 300 headquarters were activated in the country. However, not all stakeholders were well acquainted with the toolbox to allow for a general implementation of the tools and strategies, which could have supported more efficient communication and implementation of uniform responses. [1] The key areas of intervention include education, finance, governance, human resources, ICT, supervision, information, infrastructure, knowledge, logistics, organisational, planning, navigation, and miscellaneuous.