Development of Real-Time Flood Forecasting and Warning System for the Sava River Basin Klaas-Jan van Heeringen1, Hanneke Schuurmans2, Mihailo Anđelić3, Victor Simončić4, Imra Hodzic5, Sabina Hadziahmetovic5 ABSTRACT: Disastrous floods in May 2014 in Sava River basin resulted in 79 casualties and substantial economic damage in Croatia, Bosnia, Herzegovina, and Serbia. Assessments of the total damage in the area range up to 3.8 billion Euros. Distressing is the fact that besides flooding the Balkan region recently suffered from severe droughts as well. In order to be more resilient to flood and drought events, data and model output sharing is key. Better information will lead to better decisions. The Flood Forecasting and Warning System (Sava-FFWS) in which five countries jointly work together is at the forefront of transboundary cooperation. The FFWS, which is based on the well-known Delft-FEWS software, lends ample data and information enabling ultimately the decision makers to make right management decisions and implement operational measures to prevent and mitigate severe flood and drought situations on the basis of reliable forecasts of flows and discharges with a long lead time. The paper outlines key components of the Sava-FFWS illustrated with concrete application examples. Key words: real-time flood forecasting, Delft-FEWS, Sava river basin, Sava HIS, hydrological models, hydraulic models, numerical weather prediction, water levels, discharges, precipitation, temperature, snow, GIS data, dissemination Razvoj sistema za prognozu i upozorenje na velike vode u realnom vremenu za sliv reke Save APSTRAKT: Katastrofalne majske poplave iz 2014. godine u slivu reke Save pogodile su delove Bosne i Hercegovine, Hrvatske i Srbije i ostavile iza sebe pustoš: 79 osoba je izgubilo život a ogromna materijalna šteta je procenjena na preko 3.8 milijardi evra. Velika nevolja je i to što u poslednje vreme značajne delove Balkana često pogađaju i žestoke suše. Da bi se u regionu povećala otpornost na poplave i suše, od ključnog značaja je da se međusobno razmenjuju podaci osmatranja i rezultati modela za prognozu i najavu ovih fenomena – jer bolje informacije sledstveno rezultiraju u boljim odlukama i rešenjima. Sistem za prognozu i upozorenja na velike vodea u slivu reke Save (Sava-FFWS) u okviru kojeg 5 savskih zemalja rade zajedno predstavlja odličan primer dobre i višestruko korisne prekogranične saradnje u međunarodnom slivu. Za razvoj Sava-FFWS korišćen je dobro poznati Delft-FEWS softverski paket a razvijeni sistem omogućuje svestrane analize procesa oticanja i hidrološke prognoze u slivu reke Save, sa dovoljno dugim prognoznim periodom; kao takav, on daje savskim državama važan alat za donošenje pravilnih odluka i preduzimanje blagovremenih mera usmerenih na predupređenje ili ublažavanje posledica od poplava i suša u slivu reke Save. U radu su prezentirane glavne karakteristike Sava-FFWS i konkretni primeri primene. Ključne reči: prognoza velikih voda u realnom vermenu, Delft-FEWS, sliv Save, Sava HIS, hidrološki modeli, hidraulički modeli, numerička prognoza vremena, vodostaj, proticaj, padavine, temperature, sneg, GIS podaci, disseminacija prognoza 1 Deltares, [email protected] 2 Royal HaskoningDHV, [email protected] 3 Mihailo Anđelić, [email protected] 4 Eptisa, [email protected], [email protected] 5 HEIS, [email protected] 1 1 Introduction The Sava River basin covers an area of approximately 97,700 km2 including large parts of Bosnia and Herzegovina, Croatia, Montenegro, Serbia and Slovenia (see Figure 1 below). It is the largest tributary by discharge to the Danube River, with an average discharge of about 1700 m3/s, which accounts for almost 30% of the Danube’s total discharge at their confluence in Belgrade. The length of the Sava River, from its source in the western Slovenian mountains to the confluence with the Danube River, is well over 900 km [ISRBC 2017]. Figure 1. Sava River basin (data displayed on map is from the Sava GIS portal) Slika 1. Sliv reke Save (podaci prikazani na mapi preuzeti sa Sava GIS portala) Disastrous floods in May 2014 in Sava River basin resulted in 79 casualties and substantial economic damage in Croatia, Bosnia, Herzegovina, and Serbia [ICPDR 2015]. Assessments of the total damage in the area range up to 3.8 billion Euros. Distressing is the fact that besides flooding the Balkan region recently suffered from severe droughts as well. In order to be more resilient to flood and drought events, data and model output sharing is key. Better information will lead to better decisions. The Flood Forecasting and Warning System (Sava-FFWS) in which five countries jointly work together is at the forefront of transboundary cooperation. This system performs a number of sophisticated tasks and provides ample information to users that enables them to make right management decisions and implement operational measures to prevent and mitigate severe flood and drought situations on the basis of reliable forecasts of flows and discharges with a long lead time of forecast. Starting from June 2016 onward, Deltares, along with Royal HaskoningDHV, Eptisa, the Hydro-Engineering Institute of Sarajevo and Mihailo Anđelić has been implementing the World Bank- funded regional project entitled “Joint Flood Forecasting and Management in the Sava River Basin”. The project’s main objective is to develop and establish an integrated real-time flood forecasting and warning system for the entire Sava River Basin (the so called Sava FFWS), which is jointly operated and maintained by the 5 Sava riparian countries (Bosnia and Herzegovina, Croatia, Montenegro, 2 Serbia and Slovenia) in close cooperation, coordination and support of the Secretariat of the International Sava River Basin Commission (ISRBC). Operational forecasting is not only dependent on the availability of a proper forecasting system, but also on skilled, well-trained staff and good coordination between its users. Because of the complex hydrographic network of the Sava basin, many hydrological links exist between the riparian countries, while some of these links are multiple in nature. This is also reflected in the large number of beneficiary institutions (19 in total) involved in the project. This means that there is a strong need for international cooperation and requires to set-up a mature organization with well-defined and mutually agreed upon set of working procedures. 2 Stakeholders The five riparian countries of the Sava River basin are Bosnia and Herzegovina, Croatia, Montenegro, Serbia and Slovenia. These countries with the exception of Montenegro, are members of the International Sava River Basin Commission (ISRBC) that has been established to implement the Framework Agreement on the Sava River Basin (FASRB). The ISRBC Secretariat is the administrative and executive body of the ISRBC. In addition to the ISRBC, Table 1 provides an overview of the national organizations that are (direct) stakeholders in the Sava FFWS project. For efficient stakeholder interaction, project management and decision making the following organizational structure has been established within the project: Steering board. International Working Group. Country Working Groups. The Steering Board, the International Working Group and the Country Working Groups were established for the general purpose of management, monitoring and coordination of the Sava FFWS project implementation. The purpose of the Steering Board has been to monitor and make decisions about the FFWS project and its progress. The Steering Board members have been responsible for final decisions and resolving issues arising. They also comment on and approve conclusions of the International Working Group, and share their opinion about the deliverables with the World Bank. The purpose of the International Working Group has been to harmonize and verify the input of the Country Working Groups, discuss international elements of the Sava FFWS and test the milestone products before the products were considered sufficiently mature to be presented at the Steering Board meetings. The general purpose of the Country Working Groups has been to secure the input of the local interests, knowledge and workflows of each country. Nominated representatives from all five riparian countries have actively participated in the work of the above three project management bodies. As far as it has been practical and possible, the countries’ specialists who were already active in the existing ISRBC technical bodies have also been nominated to serve in these project bodies. Table 1. Stakeholders in the Sava-FFWS Project Tabela 1. Učesnici u realizaciji Sava-FFWS projecta Country Organization Role Bosnia and Federal Ministry of Agriculture, Water Policy making Herzegovina Management and Forestry Ministry of Agriculture, Forestry and Water Policy making Management of Republic of Srpska Federal Hydrometeorological Institute Operational forecasting for BiH Republic Hydrometeorological Institute Operational forecasting for BiH 3 Country Organization Role Public Institution JU “Vode Srpske” Operational forecasting for BiH Sava River Watershed Agency Operational forecasting for BiH Brčko District Government: Department of Public Safety District, Direct use of forecasts Department for agriculture, forestry and water management. Croatia Ministry of Environment and Energy Policy making Meteorological and Hydrological Service Operational forecasting for Croatia Croatian Waters Public water management