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Article A Comparative Analysis of Exceptional Flood Events in the Context of Heavy Rains in the Summer of 2010: Basin (NE ) Case Study

Gheorghe Romanescu 1 ID , Alin Mihu-Pintilie 2,* ID , Cristian Constantin Stoleriu 1, Donatella Carboni 3, Larisa Elena Paveluc 1 and Catalin Ioan Cimpianu 1

1 Department of Geography, Faculty of Geography and Geology, Alexandru Ioan Cuza University of Iasi (UAIC), RO-700505 Iasi, Romania; [email protected] (G.R.); [email protected] (C.C.S.); [email protected] (L.E.P.); [email protected] (C.I.C.) 2 Interdisciplinary Research Department, Field Science, Alexandru Ioan Cuza University of Iasi (UAIC), RO-700107 Iasi, Romania 3 Dipartimento di Scienze Umanistiche e Sociali, Università degli Studi di Sassari, Via Roma 151, 07100 Sassari, Italy; [email protected] * Correspondence: [email protected]; Tel.: +40-741-912-245

Received: 8 January 2018; Accepted: 12 February 2018; Published: 17 February 2018

Abstract: The Siret crosses northeastern (NE) Romania from the north to the south, and it discharges into the , near the city of Galati. Between 17 June and 10 July 2010, significant amounts of precipitations in the mountainous basin of Siret were recorded. The floods comprised two periods with four bimodal cycles, and they were counted as among the strongest on the Romanian territory. The exceptional floods occurred in the of Siret, , , Bistrita, Trotus, and so on. The most important compound flood wave was determined by the precipitations, which fell between 29 June and 1 July 2010, when significant amounts of rain were recorded, sometimes exceeding 80 mm/day. The high discharges on the Bistrita River—downstream from the —were controlled by complex hydro-technical works. The maximum discharge for summer floods in the year 2010 was recorded at the Dragesti hydrometric station: 2884 m3/s (historic discharge) compared with the preceding historic discharge (2850 m3/s) of the year 2008. The effects of floods were strongest in the counties of Suceava, Neamt, and Bacau. The floods on the main course of the Siret River were analyzed in correlation with the tributaries within the mountainous sector.

Keywords: continental climate; exceptional floods; historic discharge; hydro-technical works; material damage; Siret catchment basin; NE Romania

1. Introduction The year 2010 was one of the most dangerous from the perspective of catastrophic floods in Central-. The months of May–June recorded some of the strongest floods in both central and eastern Europe: , , Czech Republic, , Hungary, , , , , Bosnia, Herzegovina, Montenegro, Croatia, Romania, and so on [1–4]. On the Romanian territory, exceptional floods occurred in the rivers of Siret, , Tisa, Somes, , and Tarnave [3–7]. In Europe, the number of human losses was significant [8]: Poland—25 victims [44], Romania—six victims [3], Slovakia—three victims, Serbia—two victims, Hungary—two victims, and the Czech Republic—two victims (Figure1).

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FigureFigure 1. 1.Major Major floodsfloods events within within the the Danube Danube basin basin and and the surrounding the surrounding areas that areas occurred that occurred from May from Mayto June to June 2010. 2010.

TheThe international international literature has has analyzed analyzed in indetail detail the themost most important important floods floods that occurred that occurred over time over timearound around the world the world [9–16]. [9 From–16]. this From perspective, this perspective, the historic the floods, historic or floods,those that or produced those that important produced importantmaterial damage material or damage human losses or human, are worth losses, underscoring are worth underscoring [17–30]. The recent [17–30 catastrophic]. The recent floods catastrophic on the floodsRomanian on the territory Romanian—mostly territory—mostly in the east (Moldova in the east region) (Moldova [3–7]— region)motivated [3– scientists7]—motivated to pen scientistsscientific to works that also dealt with the issue of heavy rains [31–33]. pen scientific works that also dealt with the issue of heavy rains [31–33]. The largest catchment basin in the Romanian territory, the Siret catchment basin, comprises the The largest catchment basin in the Romanian territory, the Siret catchment basin, comprises the Siret River [2,4], and the mountains and plateaus in the catchment area have showed different patterns of Siret River [2,4], and the mountains and plateaus in the catchment area have showed different patterns precipitation [31]. At the same time, the Siret catchment basin comprises the highest number of dams in of precipitation [31]. At the same time, the Siret catchment basin comprises the highest number of Romania [33]. dams inThe Romania Siret River [33 is]. the most important hydrographic artery in Romania (after Danube): 220 m3/s, 559 3 kmThe in length,Siret River and is42,890 the most km2 importanton the Romanian hydrographic territory artery (44,871 in Romania km2 overall). (after It Danube): springs from 220 them /s, 2 2 559Ukrainian km in length, Carpathians, and 42,890 where km its on upper the Romanianstream unfolds, territory and (44,871then, its km middleoverall). and lower It springs streams from cut the Ukrainianacross the Carpathians, east of Romania. where It discharges its upper into stream the Danube unfolds, south and from then, the its city middle of Galati. and lowerIt comprises streams the cut acrossrichest the hydrographica east of Romania.l network: It discharges 1,013 rivers, into measuring the Danube 15,157 south km from overall the, citymeaning of Galati. 19.2% It of comprises Romania. the richestIts forestry hydrographical fund comprises network: 15,882 1013 km rivers,2, which measuring represents 15,15737% ofkm the overall,catchment meaning surface 19.2% and 25% of Romania.of the Itsentire forestry forestry fund fund comprises in Romania 15,882 [31 km–332], (Figure which 2a). represents 37% of the catchment surface and 25% of the entire forestryThe Siret fund basin in has Romania the following [31–33 coordinates:] (Figure2a). northern limit—47°58′ N; southern limit—45°28′ N; westernThe Siret limit basin—24°49 has′ E; the eastern following limit coordinates:—28°2′ E. The northern level differencelimit—47 ◦58 between0 N; southern the sources limit—45 and ◦ the280 N; westerndischarge limit—24 mouth ◦is49 12360 E; m. eastern The catchment limit—28 is◦ typically20 E. The asymmetrical, level difference because between it was cr theeated sources on the andright the discharge(Carpathian mouth Mts. is sector), 1236 m. on The the catchment basis of mountainous is typically tributariesasymmetrical, [2]. The because hydrographical it was created network on the rightincludes (Carpathian the Siret Mts. River sector), and its onmain the tributaries, basis of mountainous which spring tributariesfrom the mountainous [2]. The hydrographical area: Siretul Mic network (on includesthe Ukrainian the Siret territory), River and Suceav its maina, Moldova, tributaries, Bistrita, which Trotus, spring , from Ramnicu the mountainous Sarat, and Buzau. area: The Siretul only Mic (onimportant the Ukrainian tributary territory), on the left Suceava, is Barlad (Figure Moldova, 2b). Bistrita, Trotus, Putna, Ramnicu Sarat, and Buzau. The onlyThis important study emphasizes tributary on the the role left played is Barlad by locally (Figure heavy2b). rains at the onset of floods, and the importance of large in the mitigation of flood waves (Figure 2c). Another purpose of the article This study emphasizes the role played by locally heavy rains at the onset of floods, and the is to evaluate the relationship between mountainous rivers (tributaries of Siret) and water supply during importance of large reservoirs in the mitigation of flood waves (Figure2c). Another purpose of the floods. Flood waves are controlled by the reservoirs, which have taken over a part of the excessive article is to evaluate the relationship between mountainous rivers (tributaries of Siret) and water discharge in the context of climate change in recent decades. supply during floods. Flood waves are controlled by the reservoirs, which have taken over a part of the excessive discharge in the context of climate change in recent decades. Water 2018, 10, 216 3 of 17 Water 2018, 10, x 3 of 17

FigureFigure 2. 2.( a(a)) Geographic Geographic location of of the the Siret Siret catchment catchment on on the the Romanian Romanian territory; territory; spatial spatial distribution distribution of ofthe the (b ()b stud) studiedied rivers rivers and and(c) hydrometric (c) hydrometric stations, stations, with the with role of the mitigating role of mitigatingfloods in the floods Siret catchment in the Siret catchmentarea. area.

TheThe greatest greatest damage damage waswas producedproduced in County by by the the Suceava Suceava River River and and its itstributaries tributaries in in thethe Neamt Neamt County County by by Moldova Moldova and and Siret, Siret, and and in the in Bacau the Bacau County County by Trotus by Trotusand Siret and (Figure Siret 3a). (Figure In the3 a). Inloc thealities localities of Saucesti of Saucesti and Letea and Veche Letea (Bacau Veche County), (Bacau County),floods damaged floods 1110 damaged houses, 1110 4000 houses, ha of arable 4000 ha ofland, arable and land, the entire andthe infrastructure. entire infrastructure. Furthermore, Furthermore, 2137 persons were 2137 affe personscted by were the floods affected (Figure by the 3b– floodsd). The effects of the floods were significant in the counties of Suceava, Neamt, and Bacau (Figure 3e,f). For (Figure3b–d). The effects of the floods were significant in the counties of Suceava, Neamt, and Bacau the purpose of population safety, employees with the Inspectorate for Emergency Situations and the (Figure3e,f). For the purpose of population safety, employees with the Inspectorate for Emergency Romanian Army organized an intervention (Figure 3g). The total damage incurred rose to over two Situations and the Romanian Army organized an intervention (Figure3g). The total damage incurred billion Euros. rose to over two billion Euros.

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FigureFigure 3. Damage 3. Damage caused caused by by floods floods within within the Siret the catchment Siret catchment in the summer in the of summerthe year 2010: of the(a) h yearouses 2010: (a) housesdamaged damaged by the flood by theon Moldovita, flood on Moldovita,left tributary of left the tributary Moldova ofRiver the (Suceava Moldova basin); River (b) (SuceavaSiret flooded basin); (b) Siretnorth flooded from the north city fromof Bacau; the city(c) S ofiret Bacau; flooded (c )in Siret the floodedSaucesti commune in the Saucesti (Bacau commune County); ( (Bacaud) localities, County); arable land, and infrastructure affected by the floods in the middle sector of the Siret River; (e) Roads (d) localities, arable land, and infrastructure affected by the floods in the middle sector of the Siret affected by floods in the lower sector of the Siret River; (f) Temporary dams that were resistant to the River; (e) Roads affected by floods in the lower sector of the Siret River; (f) Temporary dams that floods on the Siret River; (g) Intervention of employees with the Inspectorate for Emergency Situations, g wereBacau. resistant to the floods on the Siret River; ( ) Intervention of employees with the Inspectorate for Emergency Situations, Bacau. In the Siret hydrographical space, there are 30 reservoirs, 20 of which include more than 50 ha and In144 the fish Siret culture hydrographical developments. The space, 30 reservoirs there are ma 30ke reservoirs,up a volume 20of 1 of847.632 which million include m3 (a more net volume than 50 ha 3 and 144of 1 fish206.121 culture million developments. m ). The most Theimportant 30 reservoirs reservoirs make are as up follows: a volume , of 1847.632 Somuz million II Moara, m3 (a net Izvorul Muntelui, Uz (Poiana Uzului), and so on on the tributary rivers; and Rogojesti, Bucecea, Galbeni, volume of 1206.121 million m3). The most important reservoirs are as follows: Dragomirna, Somuz II Racaciuni, Beresti, Calimanesti, and Movileni on the main course of Siret. All of the reservoirs have Moara, Izvorul Muntelui, Uz (Poiana Uzului), and so on on the tributary rivers; and Rogojesti, Bucecea, complex utility, but they do focus on flood mitigation or electric power production (mainly on the Galbeni,Bistrita Racaciuni, River). Beresti, Calimanesti, and Movileni on the main course of Siret. All of the reservoirs have complex utility, but they do focus on flood mitigation or electric power production (mainly on the Bistrita2. Materials River). and Methods In studying catastrophic floods, a globally available methodology was used. Data were obtained 2. Materials and Methods from the Siret Water Basin Administration, based in the city of Bacau. For small rivers or places without Inhydrometric studying stacatastrophictions, measurements floods, a were globally taken available for reconstituting methodology the discharges. was used. The Data assessment were obtained of fromfloods the Siret worldwide Water Basin has been Administration, analyzed by competent based in authorities, the city of Bacau.using modern, For small as well rivers as fast or places, tools and without hydrometrictechnology stations, [26,27,34 measurements–39]. were taken for reconstituting the discharges. The assessment of floods worldwide has been analyzed by competent authorities, using modern, as well as fast, tools and technology [26,27,34–39]. Water 2018, 10, 216 5 of 17

The Siret River has a network of hydrometric stations that have recorded data systematically since the year 1886 (Table1). The hydrometric stations also benefit from precipitation gauges [ 40,41] (Figure2c). Heavy rains fall hourly, and they are recorded within 24 h, according to the Berg intensity scale [42–45]. Some of the data on precipitations were obtained from the regional meteorological stations within the Siret basin. The stations are automatic, and they are centralized by the national monitoring system that is based in Bacau. As for levels and discharges, daily data were analyzed from the period of floods. For the purpose of comparison, data on the mean monthly and multi-annual levels and discharges were also used. The processed data were transposed into histograms that illustrate the evolution of levels (in the time of floods), including danger levels, the levels before and during the flood, and daily and monthly runoff, as well as the hourly variations of runoff during the flood wave.

Table 1. Characteristics of hydrometric stations on the Siret River.

Hydrometric Inauguration Latitude Longitude Altitude (m) Area (km2) Station Year Siret 1886 47◦5605300 26◦0403400 572 1637 Zvoristea 1978 47◦5101300 26◦1802600 537 1922 Hutani 1968 47◦4105700 26◦2801600 515 2152 Lespezi 1920 47◦2101900 26◦4104800 513 5899 Nicolae Balcescu 1986 46◦5504900 26◦5902100 479 6906 Dragesti 1961 46◦4304600 26◦5702100 525 11,899 Adjudu Vechi 1986 46◦0802200 27◦1104700 647 20,355 Lungoci 1921 45◦3303100 27◦3004500 539 36,095

Field observations and measurements were also conducted in June and July of the year 2010 floods, on the course of the major floodable riverbed of Siret, Suceava, Moldova, Bistrita, Trotus, Tazlau, and so on [4]. In the areas most affected by floods, where field observations were quite difficult to make, aerial photographs were taken using drones. Daily levels were followed at the most important hydrological stations, and topographic measurements were taken both upstream and downstream from the confluence. The city halls of localities within the Siret catchment, and the Inspectorates for Emergency Situations in the counties of Suceava, Neamt, and Bacau, provided the reports on damages caused by floods. Some data were taken directly on the field or by consulting the locals. Concerning the roads and railways affected by floods, materials provided by the Ministry of Transport and Communication and city halls were consulted. At the same time, satellite images provided by the Siret Water Basin Administration in Bacau, and by the National Hydrology Institute in were also analyzed. Satellite images focused on the periods of the floods. Landsat Thematic Mapper (Landsat TM) and Landsat Enhanced Thematic Mapper Plus (Landsat ETM+) multispectral satellite images were analyzed and interpreted using the Land Cover Classification System developed by Food and Agriculture Organization (FAO-LCCS). Also, to estimate the areas affected by floods, the Sentinel 2 multi-spectral imagery was used, along with Shuttle Radar Topography Mission (SRTM) elevation data, but only the visible floods with cloud coverage less than 30% were selected [3,4] (Figure4a,b). WaterWater2018 2018, 10,, 10 216, x 6 of6 17 of 17

Figure 4. (a) Geographic location of the flood events (26 June to 5 July 2010) within the Siret catchment Figure 4. (a) Geographic location of the flood events (26 June to 5 July 2010) within the Siret catchment area; (b) historical flood on the Siret River extracted from LANDSAT TM and LANDSAT ETM+ scenes area; (b) historical flood on the Siret River extracted from LANDSAT TM and LANDSAT ETM+ scenes from 3 July 2010. from 3 July 2010.

3. Results3. Results MostMost of of the the Siret Siret river river basin basin in in the the mountainous mountainous area area (Eastern (Eastern Car Carpathianspathians and and Moldavian )Subcarpathians) is is developed. developed.From From thethe westernwestern sector, the river river receives receives its its most most important important tributaries: tributaries: Suceava,Suceava, Moldova, Moldova, Bistrita,Bistrita, Trotus, Buzau, Buzau, and and so soon. on. From From the theMoldavian Plateau (east), (east),it receives it receives only onlyone one important important tributa tributary:ry: Barlad. Barlad. Therefore, Therefore, the abundant the abundant precipitations precipitations of the higher of areas the highermaintain areas a maintainrich and a rich relatively and relatively constant constant flow. From flow. a climate From a perspective, climate perspective, the Siret the catchment Siret catchment belongs to belongs the to thetemperate temperate continental continental zone, zone, with with excessive excessive accents accents in the in theeast, east, and and Baltic Baltic accents accents in inthe the north. north. PrecipitationsPrecipitations range range between between 800 800 mm–1000 mm–1000 mm in in the mountainous area, area, 600 600 mm mm–800–800 mm mm in in the the subcarpathiansubcarpathian area, area, and 450 450 mm mm–600–600 mm mm in the in theMoldavian Moldavian Plateau Plateau sector. sector.Precipitations Precipitations mainly consist mainly consistof heavy of heavy rains, especially rains, especially during the during summer the [6]. summer [6]. Usually,Usually, the the rain rain frontfront affects the the e easternastern peri peri-Carpathian-Carpathian area area along along its entire its entire length length (the year (the 1991 year 1991floods). floods). Rich Rich precipitations precipitations may also may fall also on small fall on surfaces small surfacesor sectors oreither sectors downstream either downstream (the year 2005) (the or upstream (the year 2008). Due to climatic layering, the richest precipitations fall in the subcarpathian year 2005) or upstream (the year 2008). Due to climatic layering, the richest precipitations fall in the area, and on the peripheral crests of the eastern Carpathians. Heavier rains may also be determined by subcarpathian area, and on the peripheral crests of the eastern Carpathians. Heavier rains may also be determined by the deforestation of significant mountainous forest areas, or by trees put down Water 2018, 10, 216 7 of 17

Water 2018, 10, x 7 of 17 during storms. Massive deforestations began in the year 1991, when certain forests were retroceded to individualthe deforestation owners of [3 –significant6]. Most ofmountainous the dams are forest situated areas, onor theby trees Siret put watercourse, down durin butg storms. there areMassive several damsdeforestations on mountain began tributaries, in the year too.1991, Only when two certain mountain forests were dams retroceded play a very to individual important owners role in[3– flood6]. mitigation:Most of the Bicaz dams (on are the situated Bistrita River) on the and Siret Uz watercourse, (on the same but river) there [3 are–6 ,46 several] (Figure dams4b). on mountain tributaries, too. Only two mountain dams play a very important role in flood mitigation: Bicaz (on the During the first period, from 17 June to 10 July 2010, significant amounts of precipitation were Bistrita River) and Uz (on the same river) [3–6,46] (Figure 4b). recorded in several cycles (for two or three days). In this case, the retrograde evolution of the Pontic During the first period, from 17 June to 10 July 2010, significant amounts of precipitation were Cyclone was complex, because high atmospheric pressures were recorded above the Russian Plain recorded in several cycles (for two or three days). In this case, the retrograde evolution of the Pontic and in the central–western parts of Europe. Influences of western oceanic masses were also noticed. Cyclone was complex, because high atmospheric pressures were recorded above the Russian Plain and Thein firstthe central cycle– ofwestern this complex parts of Europe. evolution Influences is represented of western by oceanic the fallen masses precipitations were also noticed. between The 23first and 25cycle June of 2010 this complex on the upper evolution and is middlerepresented streams by the of fallen the riversprecipitations within between the catchment 23–25 June of Suceava2010 on the and Moldova.upper and Flood middle waves streams had of an the average rivers within value. the The catchment second cycle of Suceava occurred and between Moldova. 26 Flood and 27waves June had 2010; rainsan averageand flood value. waves The were second recorded cycle occurred on most between rivers within26–27 June the eastern 2010; rains Carpathians. and flood wavesThe strongest were floodsrecorded occurred on most in the rivers Trotus within catchment, the eastern mostly Carpathians. on its direct The tributary, strongest which floods is occurred called Tazlau. in the TheTrotus third cyclecatchment, occurred mostly between on its 29 direct June tributary, and 1 July which 2010, is in called the catchmentTazlau. The of third Suceava, cycle Moldova,occurred between and Bistrita 29 (downstreamJune and 1 July from 2010, the in Bicaz the catchment dam), and of in Suceava, the sub-basins Moldova, of and , Bistrita (downstream Bicaz, Tarcau, from andthe Bicaz several smallerdam), tributaries.and in the sub In-basins the Trotus of Bistricioara, catchment, Bicaz, the thirdTarcau, precipitation and several smaller cycle was tributaries. weaker, In and the theTrotus flood wavescatchment, were notthe third important. precipitation The flood cycle wavewas weaker on Tazlau, and the recorded flood waves a maximum were not discharge important. of The 400 flood m3 /s. Thewave fourth on cycle Tazlau of recorded precipitations a maximum was recorded discharge from of 2 400 to 3 m³/s. July The 2010, fourth with cycleconsiderable of precipitations amounts was in the northernrecorded sector from of2 to the 3 July Siret 2010, catchment with considerable (Figure5). amounts in the northern sector of the Siret catchment (Figure 5).

FigureFigure 5. 5.Daily Daily precipitation precipitation amounts amounts (mm/day) (mm/day) between between 22–30 22 June and 201030 June in Central 2010 in-Eastern Central-Eastern Europe, Europe,based on based daily on gridded daily griddedobservational observational dataset (termed dataset E-OBS (termed v16.0 E-OBS). v16.0).

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Water 2018, 10, x 8 of 17 Historic discharges were recorded for several hydrometric stations on the rivers of Siret, Suceava, Moldova,Historic and discharges on some smallwere recorded tributaries: for Solonet,several hydrometric , Sucevita, stations Horodnic, on the Patrauteanca,rivers of Siret, Hatnuta,Suceava, Horaita,Moldova, Negostina, and on some Berehia, small and tributaries: so on. Most Solonet, of the Solca, discharges Sucevita, occurred Horodnic, during Patrauteanca, the second Hatnuta, and the thirdHoraita, cycles, Nego whenstina, theBerehia, pouring and character so on. Most of rainsof the wasdischarges determined occurred by theduring frontal the contactsecond and between the third the easterncycles, when and western the pouring masses. character They manifestedof rains was in determined the upper courseby the frontal of Siret, contact and they between continued the eastern to the Prutand western basin. The masses. climatic They manifestation manifested in is the similar upper to thatcourse of theof Sire yeart, and 2008, they when continued historic to discharges the Prut basin. were recordedThe climatic in themanifestation Prut and Suceava is similar basins. to that of the year 2008, when historic discharges were recorded in the Prut and Suceava basins. 3.1. Flood Waves in the Catchments of Suceava and Moldova, 22–26 June 2010 3.1. Flood Waves in the Catchments of Suceava and Moldova, 22–26 June 2010 Starting from 17 June 2010, a period of atmospheric instability began with the generalized rains (however,Starting the from amounts 17 June were 2010, different). a period During of atmospheric the period instability 22–24 June began 2010, with significant the generalized amounts rains of rain(however, fell in the the amounts catchments were of different). Suceava andDuring Moldova. the period The 22 rain–24 amountsJune 2010, that significant generated amounts flood wavesof rain infell the in the two catchments basins had of the Suceava following and Moldova. values: The rain (78.9 amount mm);s that Tibeni generated (72.5 mm); flood Itcani waves (107.8 in the mm); two Horodnicbasins had (67.5the following mm); Parhauti values: Brodina (47.1 mm); (78.9 Fundu mm); Tibeni Moldovei (72.5 (64.9mm); mm); Itcani Prisaca(107.8 mm); Dornei Horodnic (88.6 mm);(67.5 Guramm); HumoruluiParhauti (47.1 (54.3 mm); mm); Fundu Lungulet Moldovei (66.2 (64.9 mm); mm); Dragosa Prisaca (67.9 Dornei mm); (88.6 and mm); (74 mm). At (54.3 the hydrometricmm); Lungulet stations (66.2 mm); of Brodina, Dragosa Fundu (67.9 mm); Moldovei, and Stulpicani Dragosa, (74 and mm). Stulpicani, At the significanthydrometric amounts stations ofof precipitationsBrodina, Fundu fell Moldovei, also on 21 Dragosa, June 2010. and Stulpicani, significant amounts of precipitations fell also on 21 June The2010. most important flood waves within the first stage (with two peaks) were recorded at the followingThe most hydrometric important stations: flood Itcani waves (364 within m3/s) the and first Tibeni stage (266 (w mith3 /s) two on peaks) the Suceava were River recorded (Figure at the6); andfollowing Roman hydrometric (500 m3/s), stations: Tupilati Itcani (460 m(3643/s), m3 and/s) and Gura Tibeni Humorului (266 m3/s) (296 on mthe3/s) Suceava on the River Moldova (Figure River 6); (Figureand Roman7). Punctual (500 m3/s), flood Tupilati waves (460 also m occurred3/s), and Gura on the Humorului smaller tributaries (296 m3/s) withinon the theMoldova two basins. River (Figure In the second7). Punctual stage, flood flood waves waves also were occurred stronger, on andthe smaller they featured tributaries two within peaks: the Itcani two (883 basins. m3/s) In andthe second Tibeni (973.2stage, flood m3/s) waves on the were Suceava stronger River, and (Figure they 6featured); and Roman two peaks: (870 Itcani m 3/s), (883 Tupilati m3/s) and (660 Tibeni m3/s), (973.2 and Guram3/s) Humoruluion the Suceava (620 River m3/s) (Figure on the 6); Moldova and Roman River (870 (Figure m3/s)7)., Tupilati (660 m3/s), and Gura Humorului (620 m3/s) on the Moldova River (Figure 7).

Figure 6. Hydrograph of floodflood waves and daily intensity of precipitation between 21 June and 10 JulyJuly 2010, recorded at at the the hydrometric hydrometric stations stations on on the the Suceava Suceava River River..

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FigureFigure 7. 7.Hydrograph Hydrograph of of floodflood waveswaves and daily daily intensity intensity of ofprecipitation precipitation within within the period the period 21 June 21 Juneto 10 to 10July 2010, 2010, recorded recorded at atthe the hydrometric hydrometric stations stations on the on Moldova the Moldova River. River. Figure 7. Hydrograph of flood waves and daily intensity of precipitation within the period 21 June to 10 3.2.3.2. Flood FloodJuly Waves 2010,Waves recorded in in the the TrotusTrotus at the hydrometric Catchment,Catchment, 26stations 26–28–28 June Juneon the2010 2010 Moldova River.

3.2.The FloodThe precipitations Waves precipitations in the Trotus that that fell Catchment fell between between, 26 26– 2826 and –June28 28 June2010 June 2010 2010 in in the the Trotus Trotus catchment catchment basin basin resulted resulted in in importantimportant floods. floods. TheThe entire entire amount amount of ofwater water ran ran off the off slope the slope,, because because the soil the was soil already was moist, already due moist, to The precipitations that fell between 26–28 June 2010 in the Trotus catchment basin resulted in the mild rains that fell previously at: Lunca de Sus (59.5 mm), Ghimes Faget (79.6 mm), Goioasa (85.5 dueimportant to the mild floods. rains The that entire fell amount previously of water at: Lunca ran off de the Sus slope (59.5, because mm), Ghimesthe soil was Faget already (79.6 moist, mm), due Goioasa to mm), Targu Ocna (48.1 mm), Sulta (66.2 mm), Ciobanus (69.0 mm), Asau (85.2 mm), Lucacesti (64.5 mm), (85.5the mm), mild Targurains that Ocna fell (48.1previously mm), at: Sulta Lunca (66.2 de mm), Sus (5 Ciobanus9.5 mm), Ghimes (69.0 mm), Faget Asau (79.6 (85.2mm), mm),Goioasa Lucacesti (85.5 Scorteni (112.9 mm), Helegiu (32.0 mm), and so on. Most of the rains (>90%) fell between 26–27 June 2010. (64.5mm), mm), Targu Scorteni Ocna (48.1 (112.9 mm), mm), Sulta Helegiu (66.2 mm), (32.0 Ciobanus mm), and (69.0 so mm), on. Most Asau of(85.2 the mm), rains Lucacesti (>90%) fell(64.5 between mm), The floods occurred on the Trotus River and on its main tributaries: Ugra, Garbea, Valea Rece, Ciobanu, 26Scorteni and 27 June (112.9 2010. mm), The Helegiu floods (32.0 occurred mm), and on theso on. Trotus Most River of the andrains on (>90%) its main fell between tributaries: 26–27 Ugra, June Garbea, 2010. Asau, Tazlau, and Tazlau Sarat (Figure 8). Catastrophic floods were recorded on the rivers of Asau, ValeaThe Rece,floods Ciobanu, occurred on Asau, the Trotus Tazlau, River and and Tazlau on its Sarat main (Figure tributaries:8). CatastrophicUgra, Garbea, floodsValea Rece, were Ciobanu, recorded Trotus (at Comanesti), and Tazlau (downstream from Scorteni) (Figure 9). The maximum discharge on onAsau, the rivers Tazlau, of and Asau, Tazlau Trotus Sarat (at (Figure Comanesti), 8). Catastrophic and Tazlau floods (downstream were recorded from on Scorteni)the rivers (Figureof Asau,9 ). Trotus was 1556 m3/s (Vranceni hydrometric station). The maximum discharge on Tazlau was 780 m3/s TheTrotus maximum (at Comanesti) discharge, and on Tazlau Trotus (downstream was 1556 m from3/s (VranceniScorteni) (Figure hydrometric 9). The maximum station). The discharge maximum on (Helegiu hydrometric station) (Table 2). dischargeTrotus was on Tazlau1556 m3 was/s (Vranceni 780 m3 /shydrometric (Helegiu hydrometricstation). The maximum station) (Table discharge2). on Tazlau was 780 m3/s (Helegiu hydrometric station) (Table 2).

Figure 8. Hydrograph of flood waves and daily intensity of precipitation between 21 June and 10 July 2010, recorded at the hydrometric stations on the Trotus River. FigureFigure 8. 8.Hydrograph Hydrograph of of flood flood waves waves andand dailydaily intensityintensity of precipitation between between 21 21 June June and and 10 10July July 2010, recorded at the hydrometric stations on the Trotus River. 2010, recorded at the hydrometric stations on the Trotus River.

Water 2018, 10, 216 10 of 17 Water 2018, 10, x 10 of 17

FigureFigure 9. 9.Hydrograph Hydrograph of of flood flood waves waves and and thethe daily daily intensity intensity of precipitation of precipitation between between 21 June and 21 June10 July and 102010 July recorded 2010 recorded at the hydrometric at the hydrometric stations on stations the Tazlau on the River Tazlau. River.

Table 2. Maximum levels and discharges of Trotus and of its tributaries during the floods of the summer Table 2. Maximum levels and discharges of Trotus and of its tributaries during the floods of the of the year 2010. summer of the year 2010. Hydrometric Compared to Caution River Hmax. (cm) Qmax. (m3/s) HydrometricStation ComparedLevels to (cm) Caution 3 River Hmax. (cm) Qmax. (m /s) Trotus LuncaStation de Sus 175 Levels+25 (cm)Fl 20.0 TrotusTrotus LuncaGhimes de Faget Sus 175174 +25+24 WlFl 77.020.0 TrotusTrotus GhimesGoioasa Faget 174240 +24+40Wl Fl 23077.0 TrotusTrotus Targu Goioasa Ocna 240354 +40+54 FlFl 586230 Trotus Targu Ocna 354 +54 Fl 586 Trotus Onesti 400 +50 Fl 641 Trotus Onesti 400 +50 Fl 641 TrotusTrotus VranceniVranceni 408408 +58+58 FlFl 11556556 ValeaValea Rece Rece ValeaValea Rece Rece 158158 +8+8 WlWl 54.254.2 SultaSulta SultaSulta 200200 FlFl 41.341.3 CiobanusCiobanus CiobanusCiobanus 136136 +6+6 WlWl 8.788.78 AsauAsau AsauAsau 260260 +10+10 FlFl 114114 Fl SlanicSlanic CiresoaiaCiresoaia 230230 +30+30 Fl 81.681.6 Tazlau Scorteni 265 +15 Fl 223 TrotusTazlau HelegiuScorteni 300265 +15Dl Fl 223780 TazlaulTrotus Sarat LucacestiHelegiu 215300 +65DlWl 780147 Tazlaul Sarat Lucacesti 215 +65 Wl 147 Notes: Hmax.: Height; Wl: Warning level; Dl: Danger level; Fl: Flood level; Qmax.: Flow rate. Notes: Hmax.: Height; Wl: Warning level; Dl: Danger level; Fl: Flood level; Qmax.: Flow rate.

3.3.3.3. Exceptional Exceptional Flood Flood Waves,Waves, 17 17 June June to to 7 7July July 2010 2010 TheThe period period between between 1717 June June andand 77 July July 2010 2010 was was extremely rainy: rainy: two two small small floods floods and and two two significantsignificant floods floods were were recorded. The The floods floods occurred occurred in the in the rivers rivers of Siret, of Siret, Suceava, Suceava, Moldova, Moldova, and andBistrita Bistrita (downstream (downstream from from the the Bicaz Bicaz dam), dam), and and on on their their tributaries. tributaries. The The flood flood waves waves were were also also propagatedpropagated on on the the middle middle and and lower lower SiretSiret streams,streams, where historic historic discharges discharges were were recorded recorded at atseveral several hydrometrichydrometric stations. stations. The The amount amount of of rainfall rainfall recorded recorded between between 21 21 and–30 30 June June 2010 2010—when—when important important amountsamounts of of precipitations precipitations fell fell (Table (Table3 )—determined 3)—determined the the compound compound ffloodlood wave. wave. Exceptional Exceptional flood flood waveswaves occurred occurred in in thethe Patrauti, Darmanesti, Darmanesti, Sucevita, Sucevita, Milisauti, Milisauti, Dornesti, Dornesti, Gramesti, Gramesti, and and Zamostea rivers rivers(tributaries (tributaries of Suceava). of Suceava). The high The discharges high discharges on the on Bistrita the Bistrita River, River,downstream downstream from the from Bicaz the dam Bicaz dam(Izvorul (Izvorul Muntelui Muntelui Lake) Lake),, were wereenhanced enhanced artificially artificially through through controlled controlled overtopping overtopping (Table 4). (Table4).

Water 2018, 10, 216 11 of 17

Table 3. Daily rainfalls between 21 and 30 June 2010 in the Siret river basin.

Pluviometric Daily Rainfalls Amounts (mm) River Station 21st 22nd 23rd 24th 25th 26th 27th 28th 29th 30th Total Siret Siret 5.4 4.6 56.7 9.1 3.9 33.6 5.3 2.5 81.7 49.2 252 Siret Zvoristea - 33.6 48.1 1.8 18.5 1.6 7.7 115.1 9.9 - 236.3 Siret Lespezi - 41.6 19.1 3.7 1.2 14.3 2.2 24.9 7.7 4.5 119.2 Siret Nicolae Balcescu - 63 46 13.5 4.5 20.5 6.5 23 2.3 2.5 181.8 Siret Dragesti 5.6 - 22.6 18.1 - 15.9 20.6 0.4 12.7 - 95.9 Siret Lungoci - 0.4 2.3 1.4 8.1 3.7 - 11 - - 26.9 Suceava Brodina 1.8 45.7 33.1 - 4.6 28.8 19.9 2.5 60.3 46.3 243 Suceava Tibeni 1.6 14.7 53.7 4.1 7.4 5.2 - 74.5 44.8 62.6 268.6 Suceava Itcani - 86.4 20.7 0.6 1.8 9.3 17.6 12.7 5.1 13.6 167.8 Moldova 2.9 28.9 7.5 5.9 3.9 13.9 2.7 5.3 35.2 36.3 142.5 Suceava Prisaca Dornei - 55.4 31.5 7.1 2.1 14.9 8.4 22.3 37.9 21.8 201.4 Suceava Gura Humorului - 18.2 35.5 0.9 0.4 11.1 9.5 20.4 18.8 33.3 148.1 Suceava Tupilati - 62.8 19.3 5.8 0.9 34.2 5.8 10 2.4 4.1 145.3 Suceava Roman - 63 42 13.5 4.5 20.5 5.5 23 1.3 3 176.3

Table 4. Maximum levels and values exceeding caution levels between 26 June and 5 July 2010 for the main hydrometric stations in the Siret river basin.

26–30 June 1–5 July Hydrometric River +Caution +Caution Station H (cm) Q (m3/s) Day/Hour H (cm) Q (m3/s) Day/Hour Levels Levels Siret Siret 423 +73 Dl 1115 29/13 - - - - Siret Zvoristea 602 +266 Dl 766 29–30/23 - - - - Siret Hutani 588 +138 Dl 815 30/8–11 - - - - Siret Lespezi 614 +14 Dl 1678 29/21–23 662 +62 Dl 2049 1/5–8 Siret Nicolae Balcescu 662 +102 Dl 1339 1/1–7 728 +228 Dl 1824 2/0–1 Siret Dragesti 468 +68 Dl 2058 30/12 583 +83 Dl 2884 2/7–11 Siret Adjudu Vechi ------Siret Lungoci 669 +19 Dl 2576 1/6 669 +19 Dl 2567 3–4/12 Suceava Brodina 224 +24 Wl 151 29/4 215 +15 Wl 136 30/15 Suceava Tibeni 376 +26 Dl 973 29/8 332 +32 Fl 747 30/20 Suceava Itcani 619 +169 Dl 883 29.3 670 +220 Dl 1050 30-20 Solonet Parhauti 500 +120 Dl 346 290 - - - - Moldova Fundu Moldovei 130 +30 Wl 58.4 29/2–4 180 +30 Fl 96.5 30/17–18 Suceava Prisaca Dornei 325 +25 Fl 222 29/0 314 +14 Fl 209 30/17–18 Suceava Gura Humorului 248 +48 Wl 617 29/2 240 +40 Wl 585 30/20 Suceava Tupilati 180

The high discharges on the mountainous Siret tributaries determined the elevated levels on the main stream. Therefore, the Siret River recorded historic discharges at several hydrometric stations. However, at Lungoci, the maximum discharge of the year 2005 (4650 m3/s) was not exceeded [6]. The maximum discharge for the year 2010 summer floods was recorded at the Dragesti hydrometric station: 2884 m3/s (historic discharge), compared to the preceding historic discharge in the year 2008, which was 2850 m3/s [4] (Figure 10). Water 2018, 10, 216 12 of 17 Water 2018, 10, x 12 of 17

FigureFigure 10. 10.Hydrograph Hydrograph of of flood flood waveswaves andand dailydaily intensity of of precipitation precipitation between between 2121 June June and and 10 10July July 2010,2010, recorded recorded at at the the hydrometrichydrometric stations stations on on the the Siret Siret River River..

4. Discussion4. Discussion InIn the the last last century, century, an an increase increaseof of 0.60.6◦ °CC–0.8–0.8 ◦°CC of the air temperature has has been been recorded recorded on onthe the RomanianRomanian territory, territory, which which areare values that that are are similar similar to tothe the European European tendency tendency [47,48 [47]. This,48]. trend This is trend less is lesssignificant significant in the in thewest west and andnorthwest northwest of Romania, of Romania, but is notable but is notable in the eastern in the and eastern southeastern and southeastern regions regions[42]. The [42 average]. The averageamounts of amounts precipitations of precipitations increased slightly increased between slightly 1990–2010, between from 630 1990 mm/year and 2010,to 640 mm/year. At the same time, heavy rains recorded a high value. There is an alternation of droughty from 630 mm/year to 640 mm/year. At the same time, heavy rains recorded a high value. There is years (1961, 1963, 1965, 1986, 1990, 1994, 2000, 2003, and 2007), normal years (1968, 1971, 1976, and 2009), an alternation of droughty years (1961, 1963, 1965, 1986, 1990, 1994, 2000, 2003, and 2007), normal and rainy years (1955, 1969–1970, 1972–1973, 1978–1979, 1981, 1984, 1991, 1996–1997, 2005, 2008, and 2010) years (1968, 1971, 1976, and 2009), and rainy years (1955, 1969–1970, 1972–1973, 1978–1979, 1981, [3–7,31–34,46]. The repartition of precipitations per season underscores the extreme values for the 1984, 1991, 1996–1997, 2005, 2008, and 2010) [3–7,31–34,46]. The repartition of precipitations per Romanian territory, mostly for the Moldova Region, between precipitations that fell in the warm season seasoncompared underscores with the thehot season: extreme Iasi values +2.13 formm/year, the Romanian Suceava +2.72 territory, mm/year mostly, and for Roma then Moldova+2.74 mm/year. Region, betweenThe heavy precipitations rain character that is fellhighlighted in the warm by the season precipitation compared value withs recorded the hot within season: 24 Iasih. +2.13 mm/year, SuceavaFor +2.72 the mm/year, Siret catchment and Roman (at 120 +2.74 weather mm/year. stations The and heavy posts), rain an increasecharacter in is the highlighted occurrence by of the precipitationmaximum precipitations values recorded within within 24 h24 after h. the year 1960 is worth underscoring. This homogeneity of occurrencesFor the Siret was represented catchment (atby the 120 adjustment weather stationsof values, and which posts), was determined an increase by in the the multiplication occurrence of maximumof hydrometric precipitations stations. withinPrecipitations 24 h after that theexceed year 100 1960 mm/24 is worth h entail underscoring. significant hydrological This homogeneity effects. of occurrencesThe analysis was of represented occurrences by of the value adjustment levels exceeding of values, 100 which mm indicates was determined significant by increases the multiplication for the ofinterval hydrometric between stations. 100–160 Precipitations mm/24 h. The that intervals exceed 181 100–200 mm/24 mm/24 h or entail >200 significant mm/24 h were hydrological also taken effects.into Theaccount analysis (Tab ofle occurrences5). During flood of valuewaveslevels on the exceedingSiret catchment 100 mm(the years, indicates 1991, significant 2004–2006, increases2008, and 2010), for the intervalnumerous between amount 100 of and rainfalls 160 mm/24 comprising h. The 200 intervalsmm/24 h 181–200was recorded. mm/24 Between h or >200 2000 mm/24–2010, at hleast were five also takenepisodes into accountof catastrophic (Table floods5). During occurred: flood in wavesthe years on 2004 the Siretand 2005 catchment in the Trotus (the years, catchment 1991, and 2004–2006, on the 2008,lower and stream 2010), of numerous Siret, in the amount year 2006 of in rainfalls the comprising area (Suceava) 200 mm/24, and in hthe was years recorded. 2008 and Between 2010 in the 2000 and 2010, at least five episodes of catastrophic floods occurred: in the years 2004 and 2005 in the Trotus catchment and on the lower stream of Siret, in the year 2006 in the Arbore area (Suceava), and in the Water 2018, 10, 216 13 of 17 years 2008 and 2010 in the northern half of the Siret hydrographical space, mainly on the Suceava River, when the historic value of 1946 m3/s was recorded for discharge (Itcani hydrometric station) on 27 July 2008.

Table 5. Variations in max. rainfall occurrence, exceeding 100 mm/24 h, within the past century.

Intervals Before 1900 1901–1920 1921–1940 1941–1960 1961–1980 1981–2000 Occurrence of max. 1.7 1.7 9.9 8.3 30.5 47.9 rainfalls in 24 h Occurrence after 7.7 7.7 15.9 14.3 18.5 35.9 homogenization

The shape of flood hydrographs is different for every tributary, and for the Siret River per se. Hydrographs are influenced by the value of precipitations and their distribution in space and time. For the Suceava River, two periods comprising four cycles were delimited. The flood wave on Siret—downstream from the confluence, with the Suceava River—featured two peaks, which originated from the tributary. They merged at the Dragesti hydrometric station. An important role was played by the actions taken at the Rogoje¸stiand Bucecea reservoirs, in the flood waves, and on the upper sector of the Siret River (Table6).

Table 6. Reservoirs on the Siret River with a role in flood mitigation.

Total Volume Net Volume Depth of Lake River S NRL (ha) H NRL (cm) (mil. m3) (mil. m3) Dam (m) Rogojesti Siret 55.8 26.0 930.0 14 300 Bucecea Siret 25.0 5.86 475.0 20 271 Galbeni Siret 29.4 9.34 1123.0 29 141 Racaciuni Siret 123.03 60.67 2004.0 29 129 Beresti Siret 143.6 74.8 1800.0 29 110.7 Calimanesti Siret 60.3 15.9 740.0 22 75.0 Movileni Siret 72.0 46.53 948 13.0 48.50 Notes: NRL: Normal Retention Level; H: Height.

In the middle and lower sectors of the Siret River (at the Racaciuni, Beresti, Calimanesti, and Movileni reservoirs), correlated actions were taken to prevent the maximum discharge from exceeding 2300–2500 m3/s in the downstream sector of the Movileni dam. The first period—with two flood cycles (bimodal)—was weak, and it did not have a significant influence on the Siret River. The second period—with two cycles (bimodal)—was strong, and it had significant effects on the Siret River. The sharp peaks show the existence of pouring rain and the shape of the flood wave within the tributary basin. The hydrography of flood waves on the Moldova River is similar to that on the Suceava River, which proves that they come from the same pluvial origin. This time around, the increase on Siret was greater, because it cumulated partly with the controlled spill from upstream. The strong precipitations on the Bistrita River did not lead to flooding, because of the catchment benefits from the hydro-technical works. The 11 reservoirs controlled the Bistrita flow (Figure 11). Water 2018, 10, 216 14 of 17 Water 2018, 10, x 14 of 17

FigureFigure 11. 11.The The complex complex works on on the the Bistrita Bistrita River River..

The floods in the Trotus catchment are reversed compared with the two aforementioned basins. The firstThe (unimoda floodsl) in flood theTrotus was strong. catchment The second are reversed period was compared bimodal, with and significantly the two aforementioned weaker. They both basins. Theinfluenced first (unimodal) the Siret flood flow, wasbecause strong. they The overlapped second the period upstream was bimodal, waters. In and the significantly case of Tazlau weaker. (left Theytributary both influenced of Trotus), the situation Siret flow, is becausethe samethey as that overlapped of the main the river. upstream The Siret waters. watercourse, In the casein this of case, Tazlau (leftmay tributary be divided of Trotus), into two the distinct situation sectors: is the the same northern as that one, of without the main floods river. at The the Sirethydrometric watercourse, stations in of this case,Siret, may Zvoristea, be divided and intoHutani; two and distinct the southern sectors: one, the with northern floods one, at the without hydrometric floods stations at the hydrometricof Lespezi stations(because of Siret, of the Zvoristea, Suceava River), and Hutani; Nicolae and Balcescu the southern (because one, of thewith Moldova floods at River), the hydrometric Dragesti (weaker stations of Lespezibecause of (because the Bistrita of theRiver, Suceava and stronger, River), because Nicolae of Balcescu the upstream (because waters), of the and Moldova Lungoci (because River), Dragesti of the (weakerTrotus becauseRiver and of the the upstream Bistrita waters). River, and stronger, because of the upstream waters), and Lungoci (becauseThe of mountainous the Trotus River rivers and that the recorded upstream floods waters). in the summer of the year 2010 have more constant multiThe-annual mountainous discharges rivers compared that wit recordedh plateau floods or plain in the rivers: summer Suceava of—16.1 the yearm3/s; 2010Moldavia have—26.2 more constantm3/s; Bistrita multi-annual—62.8 m3/s; discharges and Trotus compared—34.7 m3/s. with Siret plateauis also the or largest plain river rivers: in terms Suceava—16.1 of flow on mthe3/s; 3 3 —26.2Romanian territory: m3/s; 210 Bistrita—62.8 m /s at the Lungoci m3/s; hydrometric and Trotus—34.7 station (in m 3the/s. year Siret 2000) is also, and the254 largestm /s at the river in termsdischarge of flowpoint on into the the Romanian Danube (Sendreni). territory: As 210 a result m3/s of at the the very Lungoci high discharges hydrometric recorded station in (inthe the years year 2005–2006, 2008, and 2010, the mean multi-annual discharge of Siret, at the Lungoci hydrometric station, 2000), and 254 m3/s at the discharge point into the Danube (Sendreni). As a result of the very high rose to 220 m3/s. The high continentality index of the mountainous rivers is also due to the Foehn effect. discharges recorded in the years 2005–2006, 2008, and 2010, the mean multi-annual discharge of Siret, The two significant peaks of the compound flood wave of the summer of the year 2010 were at the Lungoci hydrometric station, rose to 220 m3/s. The high continentality index of the mountainous recorded only in the catchment of Suceava and Moldova. On the upper course of Siret, there were not rivers is also due to the Foehn effect. two peaks, but only one simple peak, that is, the single-wave variation. The passage of the flood wave throughThe two the Rogojesti significant and peaks Bucecea of thereservoirs compound was strictly flood controlled. wave of theTherefore, summer the ofevacuated the year discharges 2010 were recordedwere significantly only in the mitigated catchment downstream of Suceava from and the Moldova. Bucecea dam. On the The upper second course flood ofwave Siret, peak there of the were notSuceava two peaks, River (with but only higher one flow simple than the peak, first that peak) is, added the single-wave the flows evacuated variation. from The the passageBucecea dam of the flood(mitigated wave through through thehuman Rogojesti intervention) and Bucecea and propagated reservoirs downstream, was strictly on controlled. the Siret River. Therefore, At the the evacuatedhydrome dischargestric station were of significantlyLespezi, the mitigated two peaks downstream were apparent. from the The Bucecea second dam. flood The wave second floodpeak wave—downstream peak of the from Suceava Lespezi River—advanced (with higher on the flow trail thanof the the first first, and peak) it propagated added the faster. flows Therefore, evacuated fromthe the first Bucecea flood wave dam (mitigated peak at the through Nicolae human Balcescu intervention) hydrometric and station propagated manifested downstream, itself only as on a the Siretmitigated River. inflexion. At the hydrometric The second peak station was of similar Lespezi, (in theterms two of moment) peaks were to the apparent. first peak The recorded second at floodthe waveDragesti peak—downstream hydrometric station. from Downstream Lespezi—advanced from the confluence on the trail with of the the Moldova first, and River, it propagated only one peak faster. Therefore,emerged the as first a result flood of wave a slow peak and at the continuous Nicolae Balcescu growth. hydrometric The high discharges station manifested on the Siret itself onlyRiver as— adownstream mitigated inflexion. from Bacau The—also second occurred peak due was to similarthe waters (in of terms the Bistrita of moment) River (natu to theral flows, first peakas recordedwell as atturbine the Dragesti and spilled hydrometric flows), with station. values up Downstream to 900 m3/s. The from entire the confluenceamount of water with transited the Moldova the River,reservoirs. only one peak emerged as a result of a slow and continuous growth. The high discharges on the Siret River—downstream from Bacau—also occurred due to the waters of the Bistrita River (natural

Water 2018, 10, 216 15 of 17

flows, as well as turbine and spilled flows), with values up to 900 m3/s. The entire amount of water transited the reservoirs. Taking into account the high Danube flows (accompanied by the backwater phenomenon), and certain issues with the lower stream of Siret, the discharges evacuated from the Movileni dam were initially limited to 2300 m3/s. Subsequently, the value of this discharge increased to 2500 m3/s, and the maximum value reached 2567 m3/s. Since the waters transited the reservoirs situated on Siret (on the middle and lower sectors), there was no significant discharge recorded. An additional advantage was that the Trotus flows were low during the high discharges on the rivers of Siret (upstream) and Bistrita.

5. Conclusions The mountainous rainfalls between 17 June and 10 July 2010 led to exceptional floods, compared to those in the years 2005 and 2008. The mountainous tributaries of Siret have relatively constant and high flows. They are responsible for some catastrophic floods, because they are supplied by pouring rains during the summer. The torrential character is induced by the influence of the temperate continental climate of transition, with excessive nuances. The Siret basin comprises the highest number of dams in Romania, which play a complex role, including flood mitigation. The Bistrita River holds the highest hydropower potential, and for this singular reason, it benefits from 11 reservoirs that totally control the natural runoff. The floods in the Siret catchment were determined by heavy rains that fell in the mountain area. In this case, flood waves occurred on the rivers of Suceava, Moldova, and Trotus (to which Bistrita must be added, though its runoff was controlled). The hydrometric stations of Siret, Zvoristea, and Hutani, which are situated north of the confluence with the Suceava River, recorded only small floods. On the Siret River, floods occurred in the middle and lower sector, mostly in the localities of Saucesti and Letea Veche (Bacau County). In the Trotus basin, strong floods also occurred on its main tributary: Tazlau. In the smaller catchments (Patrauti, Darmanesti, Sucevita, Milisauti, Dornesti, Gramesti, and Zamostea—all tributaries of Suceava), exceptional floods occurred, with negative effects locally. The historic discharge for the year 2010 floods was recorded at the Dragesti hydrometric station (2884 m3/s), and it was higher than the one of the year 2008 (2850 m3/s). The counties of Suceava, Neamt, and Bacau were gravely affected. The floods on Siret, which occurred in the summer of the year 2010, ranked third on the list of hydrological risk phenomena in the history of the catchment, after the similar events of the year 2005 and the year 2008.

Acknowledgments: The authors would like to express their gratitude to the employees of the Romanian Waters Agency Bucharest, Siret Water Administration Bacau, particularly to Petre Olariu, Gianina Maria Cojoc and Alina Tirnovan, hydrologists at this research and administration agency, who kindly provided a significant part of the data used in the present study. This study was supported by the Partnership in Priority Domains project PN-II-PT-PCCA-2013-4-2234 No. 314/2014 of the Romanian National Research Council, Non-destructive approaches to complex archaeological sites. An integrated applied research model for cultural heritage management—arheoinvest.uaic.ro/research/prospect. Author Contributions: Gheorghe Romanescu and Alin Mihu-Pintilie wrote the paper, analyzed the hydrological and climatic data, conceived and designed the graphic materials in GIS software; Cristian Constantin Stoleriu and Donatella Carboni contributed with materials and analysis tools; Larisa Elena Paveluc and Catalin Ioan Cimpianu performed the GIS experiments. Conflicts of Interest: The authors declare no conflict of interest.

References

1. Bissolli, P.; Friedrich, K.; Rapp, J.; Ziese, M. Flooding in eastern in May 2010—Reasons, evolution and climatological assessment. Weather 2011, 66, 147–153. [CrossRef] 2. Szalinska, W.; Otop, I.; Tokarczyk, T. Precipitation extremes during flooding in the Odra River Basin in May–June 2010. Meteorol. Hydrol. Water Manag. 2014, 2, 13–20. [CrossRef] Water 2018, 10, 216 16 of 17

3. Romanescu, G.; Stoleriu, C.C. Exceptional floods in the Prut basin, Romania, in the context of heavy rains in the summer of 2010. Nat. Hazards Earth Syst. Sci. 2017, 17, 381–396. [CrossRef] 4. Romanescu, G.; Cimpianu, C.I.; Mihu-Pintilie, A.; Stoleriu, C.C. Historic flood events in NE Romania (post-1990). J. Maps 2017, 13, 787–798. [CrossRef] 5. Romanescu, G.; Stoleriu, C.C. An inter-basin backwater overflow (the Buhai Brook and the Ezer reservoir on the River, Romania). Hydrol. Process. 2013, 28, 3118–3131. [CrossRef] 6. Romanescu, G.; Stoleriu, C.C. Causes and Effects of the Catastrophic Flooding on the Siret River (Romania) in July-August 2008. Nat. Hazards 2013, 69, 1351–1367. [CrossRef] 7. Romanescu, G.; Stoleriu, C.C.; Romanescu, A.M. Water reservoirs and the risk of accidental flood occurrence. Case study: Stanca–Coste¸stireservoir and the historical floods of the Prut river in the period July–August 2008, Romania. Hydrol. Process. 2011, 25, 2056–2070. [CrossRef] 8. International Commission for the Protection of the Danube River. Available online: https://www.icpdr.org/ icpdr_flood_report_2010.pdf (accessed on 22 January 2018). 9. Alfieri, L.; Pappenberger, F.; Wetterhall, F.; Haiden, T.; Richardson, D.; Salamon, P. Evaluation of ensemble streamflow predictions in Europe. J. Hydrol. 2014, 517, 913–922. [CrossRef] 10. Cammerer, H.; Thieken, A.H.; Verburg, P.H. Spatio-temporal dynamics in the flood exposure due to land use changes in the Alpine Valley in Tyrol (Austria). Nat. Hazards 2012, 68, 1243–1270. [CrossRef] 11. Hall, J.; Arheimer, B.; Aronica, G.T.; Bilibashi, A.; Boháˇc,M.; Bonacci, O.; Borga, M.; Burlando, P.; Castellarin, A.; Chirico, G.B.; et al. A European Flood Database: Facilitating comprehensive flood research beyond administrative boundaries. Proc. Int. Assoc. Hydrol. Sci. 2015, 370, 89–95. [CrossRef] 12. Jeneiová, K.; Kohnová, S.; Hall, J.; Parajka, J. Variability of seasonal floods in the Upper Danube River basin. J. Hydrol. Hydromech. 2016, 64, 357–366. [CrossRef] 13. Blöschl, G.; Hall, J.; Parajka, J.; Perdigão, R.A.P.; Merz, B.; Arheimer, B.; Aronica, G.T.; Bilibashi, A.; Bonacci, O.; Borga, M.; et al. Changing climate shifts timing of European floods. Science 2017, 357, 588–590. [CrossRef][PubMed] 14. Blöschl, G.; Montanari, A. Climate change impacts—Throwing the dice? Hydrol. Process. 2010, 24, 374–381. [CrossRef] 15. Halgamuge, M.N.; Nirmalathas, A. Analysis of large flood events: Based on flood data during 1985–2016 in Australia and India. Int. J. Disaster Risk Reduct. 2017, 24, 1–11. [CrossRef] 16. Holmes, R.R., Jr.; Schwein, N.O.; Shadic, C.E. Flood Risk Awareness during the 2011 Floods in the Central United States: Showcasing the Importance of Hydrologic Data and Interagency Collaboration. Leadersh. Manag. Eng. 2012, 12, 101–110. [CrossRef] 17. Kelman, I.; Gaillard, J.C.; Mercer, J. Climate Change's Role in Disaster Risk Reduction's Future: Beyond Vulnerability and Resilience. Int. J. Disaster Risk Sci. 2015, 6, 21–27. [CrossRef] 18. Kolen, B.; Slomp, R.; Jonkman, S.N. The impacts of storm Xynthia February 27–28, 2010 in France: Lessons for flood risk management. J. Flood Risk Manag. 2013, 6, 261–278. [CrossRef] 19. Di Baldassarre, G.; Claps, P. A hydraulic study on the applicability of flood rating curve. Hydrol. Res. 2011, 42, 10–19. [CrossRef] 20. Li, Z.; Zhang, Y.; Zhu, Q.; He, Y.; Uao, W. Assessment of bank gully development and vegetation coverage on the Chinese Loess Plateau. Geomorphology 2015, 228, 462–469. [CrossRef] 21. Lichter, M.; Klein, M. The effect of river floods on the morphology of small river mouths in the southeastern Mediterranean. Z. Geomorphol. 2011, 55, 317–340. [CrossRef][PubMed] 22. Lóczy, D.; Czigány, S.; Pirkhoffer, E. Flash Flood Hazards. In Studies on Water Management Issues; Kumarasamy, M., Ed.; InTech: Rijeka, Croatia, 2012; pp. 27–52. ISBN 978-953-307-961-5. 23. Lóczy, D.; Kis, E.; Schweitzer, F. Local flood hazards assessed from channel morphometry along the River in Hungary. Geomorphology 2009, 113, 200–209. [CrossRef] 24. De Moel, H.; van Alphen, J.; Aerts, J.C.J.H. Flood maps in Europe—Methods, availability and use. Nat. Hazards Earth Syst. Sci. 2009, 9, 289–301. [CrossRef] 25. Müller, U. Implementation of the flood risk management directive in selected European Countries. Int. J. Disaster Risk Sci. 2013, 4, 115–125. [CrossRef] 26. Parker, D.; Fordham, M. An evaluation of flood forecasting, warning and response systems in the . Water Resour. Manag. 1996, 10, 279–302. [CrossRef] Water 2018, 10, 216 17 of 17

27. Prudhomme, C.; Genevier, M. Can atmospheric circulation be linked to flooding in Europe? Hydrol. Process. 2011, 25, 1180–1190. [CrossRef] 28. Schneider, C.; Laize, C.L.R.; Acreman, M.C.; Flörke, M. How will climate change modify river flow regimes in Europe? Hydrol. Earth Syst. Sci. 2013, 17, 325–339. [CrossRef] 29. Whitfield, P.H. Floods in future climates: A review. J. Flood Risk Manag. 2012, 5, 336–365. [CrossRef] 30. Zhou, Z.; Liu, S.; Zhong, G.; Cai, Y. Flood Disaster and Flood Control Measurements in Shanghai. Nat. Hazards Rev. 2016, 18, B5016001. [CrossRef] 31. Romanescu, G. Siret river basin planning (Romania) and the role of wetlands in diminishing the floods. WIT Trans. Ecol. Environ. 2009, 125, 439–453. [CrossRef] 32. Romanescu, G.; Zaharia, C.; Stoleriu, C.C. Long-term changes in average annual liquid flow river Miletin (Moldavian Plain). Carpathian J. Earth Environ. Sci. 2012, 7, 161–170. 33. Romanescu, G.; Nistor, I. The effect of the July 2005 catastrophic inundations in the Siret River’s Lower Watershed, Romania. Nat. Hazards 2011, 57, 345–368. [CrossRef] 34. Demeritt, D.; Nobert, S.; Clake, H.L.; Pappenberger, F. The European Flood Alert System and the communication, perception, and use of ensemble predictions for operational flood risk management. Hydrol. Process. 2013, 27, 147–157. [CrossRef] 35. Hall, J.; Arheimer, B.; Borga, M.; Brázdil, R.; Claps, P.; Kiss, A.; Kjeldsen, T.R.; Kriauˇciunien¯ e,˙ J.; Kundzewicz, Z.W.; Lang, M.; et al. Understanding flood regime changes in Europe: A state-of-the-art assessment. Hydrol. Earth Syst. Sci. 2014, 18, 2735–2772. [CrossRef] 36. Kourgialas, N.N.; Karatzas, G.P.; Nikolaidis, N.P. Development of a thresholds approach for real-time flash flood prediction in complex geomorphological river basins. Hydrol. Process. 2012, 26, 1478–1494. [CrossRef] 37. Kundzewicz, Z.W.; Pinskwar, I.; Brakenridge, G.R. Large floods in Europe, 1985–2009. Hydrol. Sci. J. 2013, 58, 1–7. [CrossRef] 38. Rusnák, M.; Lehotskey, M. Time-focused investigation of river channel morphological changes due to extreme floods. Z. Geomorphol. 2014, 58, 251–266. [CrossRef] 39. Iacobellis, V.; Fiorentino, M.; Gioia, A.; Manfreda, S. Best Fit and Selection of Theoretical Flood Frequency Distributions Based on Different Runoff Generation Mechanisms. Water 2010, 2, 239–256. [CrossRef] 40. Cojoc, G.M.; Tîrnovan, A.; Obreja, F. Modern means of monitoring the hydrological regime in the Siret River Basin (Romania). Georeview 2014, 24, 38–53. [CrossRef] 41. Cojoc, G.M.; Romanescu, G.; Tirnovan, A. Exceptional floods on a developed river. Case study for the Bistrita River from the Eastern Carpathians (Romania). Nat. Hazards 2015, 77, 1421–1451. [CrossRef] 42. Haylock, M.R.; Hofstra, N.; Klein Tank, A.M.G.; Klok, E.J.; Jones, P.D.; New, M. A European daily high-resolution gridded data set of surface temperature and precipitation for 1950–2006. J. Geophys. Res. 2008, 113.[CrossRef] 43. Jia, B.; Zhong, P.; Wan, X.; Xu, B.; Chen, J. Decomposition-coordination model of reservoir group and flood storage basin for real-time flood control operation. Hydrol. Res. 2015, 46, 11–25. [CrossRef] 44. Wilk, S.; Kinal, J. Flooding in Poland in 2010 as a Exemplification of Efforts of the Polish Social Work Services in Case of Disaster. Mediterr. J. Soc. Sci. 2014, 5, 315–321. [CrossRef] 45. Brakenridge, G.R.; Syvitski, J.P.M.; Niebuhr, E.; Overeem, I.; Higgins, S.A.; Kettner, A.J.; Prades, L. Design with nature: Causation and avoidance of catastrophic flooding, Myanmar. Earth-Sci. Rev. 2017, 165, 81–109. [CrossRef] 46. Romanescu, G.; Miftode, D.; Mihu-Pintilie, A.; Stoleriu, C.C.; Sandu, I. Water Quality Analysis in Mountain Freshwater: Poiana Uzului Reservoir in the Eastern Carpathians. Rev. Chim. (Bucharest) 2016, 67, 2318–2326. 47. Pachauri, R.K.; Meyer, L.A. (Eds.) IPCC: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change; Intergovernmental Panel on Climate Change (IPCC): Geneva, Switzerland, 2014; p. 151. 48. Sraj, M.; Viglione, A.; Parajka, J.; Blöschl, G. The influence of non-stationarity in extreme hydrological events on flood frequency estimation. J. Hydrol. Hydromech. 2016, 64, 426–437. [CrossRef]

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