Nat. Hazards Earth Syst. Sci., 17, 381–396, 2017 www.nat-hazards-earth-syst-sci.net/17/381/2017/ doi:10.5194/nhess-17-381-2017 © Author(s) 2017. CC Attribution 3.0 License. Exceptional floods in the Prut basin, Romania, in the context of heavy rains in the summer of 2010 Gheorghe Romanescu and Cristian Constantin Stoleriu Faculty of Geography and Geology, Department of Geography, Alexandru Ioan Cuza University of Iasi, Bd. Carol I, 20 A, 700505 Iasi, Romania Correspondence to: Gheorghe Romanescu ([email protected]) Received: 30 August 2016 – Discussion started: 12 September 2016 Revised: 4 January 2017 – Accepted: 13 February 2017 – Published: 10 March 2017 Abstract. The year 2010 was characterized by devastating ina, and Montenegro (Bissolli et al., 2011; Szalinska et al., flooding in central and eastern Europe, including Romania, 2014) (Fig. 1). The strongest floods from 2010 were regis- the Czech Republic, Slovakia, and Bosnia-Herzegovina. This tered in the Danube basin (see Table 1). For Romania, we study focuses on floods that occurred during the summer of underlined the floods from the basins of Prut, Siret, Moldova, 2010 in the Prut River basin, which has a high percentage and Bistri¸tarivers. The most devastating floods in Romania of hydrotechnical infrastructure. Strong floods occurred in occurred in Moldavia (Prut, Siret) and Transylvania (Tisa, eastern Romania on the Prut River, which borders the Re- Somes, Tarnave, Olt). The most deaths were recorded in public of Moldova and Ukraine, and the Siret River. Atmo- Poland (25), Romania (six on the Buhai River, a tributary spheric instability from 21 June to 1 July 2010 caused re- of the Jijia), Slovakia (three), Serbia (two), Hungary (two), markable amounts of rain, with rates of 51.2 mm/50 min and and the Czech Republic (two) (Romanescu and Stoleriu, 42.0 mm/30 min. In the middle Prut basin, there are numer- 2013a, b). ous ponds that help mitigate floods as well as provide water Floods are one of the most important natural hazards in for animals, irrigation, and so forth. The peak discharge of Europe (Thieken et al., 2016) and on earth (Merz et al., 2010; the Prut River during the summer of 2010 was 2310 m3 s−1 at Riegger et al., 2009). They generate major losses of human the Rad˘ au¸ti-Prutgauging˘ station. High discharges were also lives and also property damage (Wijkman and Timberlake, recorded on downstream tributaries, including the Baseu, Ji- 1984). For this reason, they have been subject to intense re- jia, and Miletin. High discharges downstream occurred be- search, and significant funds have been allocated to mitigat- cause of water from the middle basin and the backwater ing or stopping them. According to Merz et al. (2010) “the from the Danube (a historic discharge of 16 300 m3 s−1). The European Flood Directive on the assessment and manage- floods that occurred in the Prut basin in the summer of 2010 ment of flood risks (European Commission, 2007) requires could not be controlled completely because the discharges developing management plans for areas with significant flood far exceeded foreseen values. risk (at a river basin scale), focusing on the reduction of the probability of flooding and on the potential consequences to human health, the environment and economic activity.” (p. 511). Several studies investigated catastrophic floods or 1 Introduction the floods that generated significant damage. They focused on the statistical distribution of the maximum annual dis- Catastrophic floods occurred during the summer of 2010 in charge using GEV and the links with the basin geology (Ahi- central and eastern Europe. Strong flooding usually occurs lan et al., 2012), climate change impacts on floods (Alfieri et at the end of spring and the beginning of summer. Among al., 2015; Detrembleurs et al., 2015; Schneider et al., 2013; the most heavily affected countries were Poland, Romania, Whitfield, 2012), disastrous effects on infrastructures such the Czech Republic, Austria, Germany, Slovakia, Hungary, as transportation infrastructures and their interdependence Ukraine, Serbia, Slovenia, Croatia, Bosnia and Herzegov- Published by Copernicus Publications on behalf of the European Geosciences Union. 382 G. Romanescu and C. C. Stoleriu: Exceptional floods in the Prut basin, Romania Figure 1. The Danube catchment and the location of the most important floods that occurred from May to June 2010. (Berariu et al., 2015), historical floods (Blöschl et al., 2013; 2 Study area Strupczewski et al., 2014; Vasileski and Radevski, 2014) and their links to heavy rainfall (Bostan et al., 2009; Diakakis, The Prut River’s catchment is situated in the north-eastern 2011; Prudhomme and Genevier, 2011; Retsö, 2015), the Danube basin. It is surrounded by several other catchments: public perception of flood risks (Brilly and Polic, 2005; Feld- the Tisa to the north-east (which spans Ukraine, Romania, man et al., 2016; Rufat et al., 2015), land use changes and and Hungary), the Siret to the west (which is partially in flooding (Cammerer et al., 2012), the evolution of natural Ukraine), and the Dniestr (in the Republic of Moldova) to risks (Hufschmidt et al., 2005), geomorphological effects of the north-east. The Prut catchment occupies eastern Romania floods in riverbeds (Lichter and Klein, 2011; Lóczy and Gy- and the western part of the Republic of Moldova (Fig. 2). The enizse, 2011; Lóczy et al., 2009, 2014; Reza Ghanbarpour Prut River begins in the Carpathian Mountains in Ukraine et al., 2014; Romanescu and Nicu, 2014), the spatial distri- and empties into the Danube near the city of Galati. The bution of floods (de Moel et al., 2009; Parker and Fordham, catchment measures 27 500 km2, of which 10 967 km2 lies 1996), and the interrelation between snow and flooding (Re- in Romania (occupying approximately 4.6 % of the surface vuelto et al., 2013). of Romania). The Prut catchment basin spans three topographic lev- The Prut River is the second longest river in Romania, at els: mountains, plateaus, and plains. The surface and un- 952.9 km in length. It is a cross-border river, with 31 km in derground water supply to the Prut varies by region and is Ukraine and 711 km in the Republic of Moldova. The mean extremely influenced by climatic conditions. This study un- altitude of the midstream sector of catchment area is 130 m, derscores the role played by local heavy rains in the occur- and for the downstream sector it is 2 m. The Prut has 248 trib- rence of floods, as well as the importance of ponds, mainly utaries. Its maximum width is 12 km (in the lower reaches, the Stânca-Coste¸stireservoir, in the mitigation of backwa- Brates Lake) and its average slope is 0.2 %. Its hydrographic ters. We also analyse the local contribution of each catchment network measures 11 000 km in total, of which 3000 km basin on the right side of the Prut to the occurrence of the ex- are permanent streams (33 %) and 8000 km are intermittent ceptional floods in the summer of 2010. Finally, we consider (67 %). The network has the highest density in Romania at − − the upstream discharge and its influence on the lower reaches 0.41 km km 2 (the average density is 0.33 km km 2/. of the Prut. Nat. Hazards Earth Syst. Sci., 17, 381–396, 2017 www.nat-hazards-earth-syst-sci.net/17/381/2017/ G. Romanescu and C. C. Stoleriu: Exceptional floods in the Prut basin, Romania 383 Table 1. Overview of main flood events for the Danube River basin in 2010, as forecasted by EFAS and/or reported in international online news media (ICPDR, 2010). From To River basin Country EFAS Date FAS Confirmed? Comment (dd.mm) (dd.mm) Affected Affected Alert sent? Alert sent 20.II 4.III Sava HR/RS Yes 24 Feb Yes Severe flooding in central and E (Flood Watch) Serbia, and in Sava and Morava river systems. 21.II 28.II Velika Morava RS Yes 16 Feb Yes Severe flooding in eastern Serbia (Flood watch) Feb Feb Koeroes RO/HU Yes 16 Feb No (No reports found on online news (Flood watch) media). Events to be confirmed by partners in next annual EFAS meet- ing 1.III 5.III Danube RO/BG Yes 3 Mar Yes Severe flooding in S Romania and (Flood alert) in NW and N Bulgaria. March March Somes/Mures/ RO/HU Yes 18 Mar No No reports found on online news Koeroes (Flood alert) media. Events to be confirmed by partners in next annual EFAS meet- ing 15.V 30.V Danube/Oder SK/PL/CZ/HU Yes 12 May Yes Extensive flooding in central and (Flood alert) eastern Europe, esp. Poland, Czech Republic, Slovakia, Hungary, and Serbia. Late June July Siret/Prut/ RO/MD No – Yes Severe flooding in NE Romania Moldova/ kills 25 people, also some in coun- Bistri¸ta ties in Moldova. 15.VII 15.VII Prut/Olt RO Yes 7 July Yes Maximum flood alert on Prut River (Flood alert) in E Romania, along border with Moldova. 17.IX 19.IX Sava/Soca HR/SL Yes 18 Sep Yes Severe flooding in Slovenia kills (Flood alert) three people. Croatia also affected. Late Nov Early Dec Drina RS Yes 29 Nov Yes Severe flooding in Bosnia, Serbia, (Flood alert) and Montenegro, with river Drina at highest level in 100 years. 3.XII 8.XII Sava HR Yes 5 Dec Yes Heavy rain causes devastating (Flood alert) flooding in the Balkans, esp. Bosnia and Herzegovina, Croatia, Montenegro, and Serbia. 9.XII 9.XII Tisza HU/RS No – Yes Snowmelt and swollen rivers flood 3000 km2 of arable land, esp. near Szeged, on Tisza River in SE Hun- gary.