Hydrometeorological risk phenomena in the – Turda Depression.

CĂTĂLINA MĂRCULEŢ1, IOAN MĂRCULEŢ2, 1. Institute of Geography, Bucharest, Romania 2. "I.L. Caragiale" National College, Bucharest, Romania e-mail: [email protected]

Abstract

In order to assess the vulnerability of communities to extreme hydrometeorological phenomena, observations on their onset and development should aim at quantifying intensity and frequency, also establishing and foreseeing possible damage. The present study focuses on a few atmospheric phenomena registered in the Alba Iulia – Turda Depression over the 2002-2006 interval, given that the damage incurred involved aspects of risk. Hazardous atmospheric phenomena, heavy rainfall in the main, led to other natural risks affecting both the environment and the socio-economic activity. Apart from atmospheric causes, the risk for other natural events are related to local particularities, e.g. lithological structure (sandy-clay substrate), landform (slopes and highly fragmented relief) and soils (little forestland and grassland due to human pressure – dominantly arable land and numerous human settlements). Houses and annexes, as well as socio-economic constructions were damaged, lots of animals and poultry perished, national, county, communal and forester's roads, bridges and foot-bridges were washed away or disaffected, crops were flooded, trees were brought to the ground, electrical and telephone networks were destroyed. Heavily affected were the road infrastructure, the hydroelectrical constructions the socio- economic units, the electrical and telephone networks and agriculture generally. The number of catastrophic situations, unusually high in 2005, represented 44% of all the interventions made over the past ten years to limit and remove flood effects. Negative hydrometeorological phenomena were found to occur mainly in summer, especially in June and July when torrential rains and floods are common. Significant damage is recorded also in spring (March, April), when snowmelt coupled with rich precipitation may trigger extensive flooding. Analysing the above situations we could say that most flood events were registered in small drainage basins and in torrential basinettes. Limiting the negative effects calls for the afforestation of slopes in the affected drainage basins, the construction of dams, the execution of works to consolidate or even change the direction of the roads running close to some watercourses.

Key words: hydrometeorological risk phenomena, risk management, Alba Iulia – Turda Depression, Romania.

Introduction A vast research programme within the International Decade for Natural Disaster Reduction (IDNDR) was implemented in the last decade of the 20th century. The programme, carried out under the UN aegis, had in view to contribute to diminishing the effects of natural disasters. The conclusion was that such interdisciplinary efforts should continue. As a result, the International Strategy for Disaster Reduction, put in place at the beginning of the 21st century, was aimed at intensifying multidisciplinary research efforts concerning the impact of hazards on society, this time with highlight on risk management instead of risk protection. The idea was to have risk prevention strategies included into sustainable development plans. Awareness of the fact that 90% of the natural hazards are triggered by weather, climate and water, made Disaster Prevention and Mitigation the theme of the 2006 anniversary of the World Meteorological Organization (WMO). The findings revealed that 65% of all natural disaster-induced economic damages registered over the 1992-2001 period were caused by hydrometeorological disasters. While natural hazards cannot be avoided, integrating risk assessment and early warnings into measures to prevent and reduce them may hinder risk effects from growing into disasters.

______BALWOIS 2008 - Ohrid, Republic of Macedonia - 27, 31 May 2008 1/7 Appraising the vulnerability of communities to extreme phenomena implies observations to enable quantifying the intensity and frequency of events, outline and predict damage. Therefore, systematic studies of meteorological observations on natural hazards and their impact represent a reliable risk management basis.

Case-studies (2002-2006) In line with the introduction, the paper expounds on some hydrometeorological phenomena that affected the environment and society of the Alba Iulia – Turda Depression (a subunit of the Transylvanian Depression which lies in the central part of Romania) over the 2002-2006 period. • July 16-18, 2002 registered marked atmospheric instability manifest by a strong cyclonic activity due to a high temperature-pressure contrast between Mediterranean and Polar masses of air at the eastern periphery of the Azore Anticyclone. Central Europe was crossed successively by cold and warm fronts along a median line, starting from the Balkan Peninsula and moving northwards towards the Scandinavian Peninsula. This swift succession of front lines was felt also on the territory of the Alba Iulia – Turda Depression, unleashing heavy rainfalls, locally torrential, thunderstorms, gusts of wind and local hail-associated showers. The strong rainfalls enhanced run-off on slopes, floodwaves in catchments, entailing alluvial material and causing damage to households, roads, croplands, electrical and telephone lines, etc. Apart from atmospheric causes these risk phenomena were enhanced by the area’s lithology (sand- clay substrate), landforms (slopes and much fragmentation), soils and a reduced forest and grass cover, the consequence of human activity (mainly arable land use and lots of settlements). The quantity of rain fallen on those three days and registered by met stations and rain-gauge points stood between 36.7 mm and 69.6 mm. They represented 50-90% of the July average (observation points Ocna Mureş, Benic and ). The rains fallen within 24 hours reached 59.2 mm at Ocna Mureş, 44 mm at Benic and 30 mm at Ighiu. However, torrential local precipitation produced damages also in other localities than at the observation sites (Fig. 1). The losses incurred by these extreme phenomena at , , Livezile, and Stremţ amounted to 5,966,000,000 lei (ca. 180,000 €). • June 2, 2003, rain started pouring on Ţelna Village, Ighiu Commune between 16.00 p.m. and 17.20 p.m. Their torrential character (43 mm at Ighiu) entailed run-off on slope. One person caught in the events went missing. In 22 locations households, sheds, gardens, wells, cellars and kitchens were filled with flood-carried mud. Thunderstorms damaged the Ighiu substation and electricity supply was briefly cut (Fig. 1). • April 13-14, 2004, torrential showers formed floodwaves on the Mureş, Arieş, , , , Pianu rivers and their tributaries, run-off on slope and landslides. Heavy rainfall values averaged over 20 l/m2/24 hrs, with 42.8 at Sebeş, 38.4 at Ighiu, 32.0 at Benic, 31.9 in Alba Iulia, 30.0 at Teiuş, 28.2 at , etc. Water quantities were not excessive, but the intensity of precipitation led to channel waters swiftly rising and to overflows on most watercourses (Fig. 1), with violent manifestation of the floods on small streams, in particular. That water levels would rapidly grow over large areas was made possible also by the incipient stage of vegetation, the poor forest cover in the respective drainage basins, the steep slopes and the water- saturated soils. These violent phenomena reactivated and enhanced erosional processes and deposition of alluvia in channels. The outcome was damaged roads, bridges and foot-bridges, households, croplands, etc., most affected being the settlements of Sântimbru and Stremţ. • July 23, 2004. Torrential rains associated with hail fell in the Galda, Geoagiu and Ighiu drainage basins, totalling 41.0 mm/24 hrs at Benic, 40.0 mm at Ighiu, 41.0 mm at Bărăbanţ and 48.2 mm in Alba Iulia. As a result, level increases and overflows occurred on the small streams (without hydrometric control) and in the gully area of the Galda River basin. The floods carried big quantities of sediment, depositing it at the slope-foot of the limitrophe terrains and in stream channels. Bank erosion was also reactivated and amplified. At , squally winds blew and hail stones of up to 10 mm in diameter fell; Benic, the most affected settlement, was hit by a 45 mm-long rain-and-hail storm that left 15 houses roofless,

______BALWOIS 2008 - Ohrid, Republic of Macedonia - 27, 31 May 2008 2/7 destroying almost all vegetable gardens and orchards; at Mesentea, Galda de Sus and Cetea, crops were washed away in proportion of 25%, 65% and 70%; 50% of the Galda de Jos vine culture was lost. The Galda de Jos hailstorm affected 50% of the 510 hectares of cultivated land (180 ha of orchard, 260 ha of cereal crops, 45 ha of vine culture and 25 ha of vegetables). Estimated losses were close to 3 billion lei. In Stremţ Commune, run-off on slope destroyed some 0.22 km of the County Road 750 C, estimated loss 50 million lei (Fig. 1). On that day, the Stremţ, Galda de Jos, Gârbova, Pianu and Şibot communes totalled a loss of 6,080,000,000 lei (ca. 140,000 €). • March 17-18, 2005. Sudden temperature rises associated with snowmelt increased water-flows up to flooding levels, affecting households and croplands. On March 15, a gradual warming process began, with a peak on the 17th and 18th : positive diurnal temperatures, nocturnal values of 3-10°C, on average, and diurnal maxima of 8-19°C. Mountain showers falling over the melting snow layer produced flood waves on the Mureş, Arieş, Târnava Mică, Ampoi, Geoagiu, Galda, Pianu rivers and their tributaries, as well as run-off on slope. About 200 m of the road linking Aiud city to Gâmbaş settlement were flooded, inhabitants riding a lorry tractor. Noteworthy, in Alba Iulia, the Mureş River safety level rose by 85 cm. Bank erosion on the Mureş, Ampoi, Arieş and Geoagiu was reactivated and if the process goes on it may incur significant damage for the reparian population of the Ampoi, River who may lose its cropland; besides, the National Highway (DN 74) infrastructure, and the electricity transmission towers could be deteriorated. Erosion on the righthandside of the Mureş River became particularly obvious in front of Beldiu settlement, and was reactivated in front of the flooding flap of the Bega UPS Ocna Mureş Company and the water supply by-pass line of the SC Apa CTTA Alba Company. In the localities of Aiud, Ocna Mureş, Teiuş, , Mirăslău, Mihalţ, Pianu, Rădeşti, Săliştea, Stremţ and the floods damaged households, roads, foot-bridges, croplands, hydrotechnical constructions, electrical networks and other objectives. Croplands and county roads were severely affected particularly in Stremţ Commune. The losses produced by the March 17th-18th events in the Alba Iulia –Turda Depression amounted to 15,320,000,000 lei (over 425,000 €). • On the night of May 26-27, 2005, a severe storm damaged the electrical network of several settlements. A black out in one of Alba Iulia’s residential districts was due to the failure of six substations. Heavy rainfall caused damage in Alba Iulia city and in the neighbouring localities; several segments of a county road were covered with sediments, disrupting the traffic flow (Fig. 1). • June 5-20, 2005 heavy showers, even torrential over relatively large areas, fell within two time- intervals: June 5-10 and 16-20, when the phenomena took on severer manifestations, incurring serious damage. The cumulated quantities over the two intervals registered at some meteo stations and water-gauge points came close to the multiannual mean values of June (80-100 l/m2). As a result, the floodwaves on the small tributaries of the Mureş River (the Aiud, Geoagiu, Galda and Cricău) overflew the limitrophe areas, reactivating bank erosion and much run-off on slope, damaging households, roads, electrical networks, croplands, etc. Most affected was Aiud city (Fig. 1), as well as county, communal and forester’s roads. • July 9-17, 2005 witnessed unstable weather with heavy showers, torrential over large areas, associated with thunderstorms and temporary gusts of wind. The rains of July 11 and 12, in particular increased flow rates and run-off on slope. Cumulated quantities of precipitation registered in the 10-14 interval by met stations and rain-gauge points (60-70 mm) came close to the July multiannual means (70-110 mm). Huge quantities of precipitation and moreover their intensity of reached even 2 l/min within short time-spam (5-10 min). Heavy and intense falls on the 11th and 12th steep slopes and oversaturated soils led to the sudden water level rise on most small watercourses, safety levels on the Mureş, Aiud and Geoagiu rivers being surpassed. Overflows in the Mureş floodplain areas, enhanced flood-induced erosion also on the Aiud, Galda, Ighiu and their tributaries. The Aiud water-gauge station’s records show historical maxima being overcome on the Aiud River by the July 12-13 flood events. In Alba Iulia, the cumulated effects of precipitation from previous months, led to ground water levels rising and flooding the basement of several houses.

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Fig. 1. The Mureş Corridor in the Alba Iulia – Turda Depression. Map of hydrometeorological risk- prone areas. Case-studies: 1. July 2002; 2. June 2003; 3. April 2004; 4. July 2004; 5. May 2005; 6. June 2005; 7. July 2005; 8. settlement.

______BALWOIS 2008 - Ohrid, Republic of Macedonia - 27, 31 May 2008 4/7 The isolated showers fallen in the afternoon of July 17 averaged a total of up to 20 l/m2/24 hrs, rising the Aiud River level at Livezile by 230 cm (Aiud water-gauge station) which correspounds to top discharges of 44.2 cm/sec. As a result houses, croplands, national highways, county, communal and forester’s roads, bridges and foot-bridges, defence structure, electrical networks, etc. were flooded. The most dramatic situation throughout the Alba Iulia – Turda Depression had the city of Aiud, where torrential rains affected 300 families, and the Aiud Valley which was overflown (Fig. 1). A number of 130 people were evacuated (Photos 1, 2, 3) and because five substations and two tension towers had been destroyed hundreds of dwellings had no electricity. The Aiud city rail bridge being flooded domestic and international traffic was disrupted for some four hours and several trains were significantly delayed. In Aiud and Livezile Commune, torrential rainfall affected 320 household annexes, the cellars and basements of 206 households, 40 wells, a metal bridge, 400 m of county road, and 50 m of protection dam were eroded. In Aiud city, regulation works on the homonymous river were affected by abutment damage along 130 m; in Măgura Village, 10 m of road gave way (Photo 4) and a house close to the local bridge was damaged. In Şard settlement, protection of the bank on the Ighiu River was impaired along 30 m.

Photo 1. Bridge in Aiud washed-away. Photo 2. Flooded streets in Aiud.

Photo 3. Evacuated people in Aiud. Photo 4. Sunken road.

As a consequence, the phenomena that raged in the respective period caused huge losses, actually the biggest in 2005. • The summer of 2006 (June 2 - July 10) was again struck by negative phenomena. Showers and hailstones, thunderstorms and gusts of squally winds were registered within two intervals: June 2-4 and June 19-21. Here and there, significant quantities of rain water would fall throughout the study period, also associated with torrential rains, thunderstorms, high winds, hail and floods. Their manifestations were extremely violent over a very short time-span. Heavy precipitation, steep slopes, oversaturated soils, made waters rise suddenly and successively, safety levels being surpassed at the Ocna Mureş, Aiud and Benic water-gauge stations, with overflows on the Mureş, Galda, Aiud, Lopadea, Mirăslău, Pianu and on other rivers, as well as run-off on slope. In 2006, safety levels in Aiud city were again exceeded and a historical maximum discharge was registered. Stremţ and Mirăslău settlements were hit by wind and hailstorms.

______BALWOIS 2008 - Ohrid, Republic of Macedonia - 27, 31 May 2008 5/7 The biggest losses in the Alba Iulia – Turda Depression, totalling 8,273,000 RON∗ (over 2,330,000 €), had Aiud, Mirăslău, Galda de Jos and Livezile. The areas afferent to the Arieş and the Mureş basins were also the most affected ones – roads, croplands, households and annexes. * In all the cases discussed in this paper, the untoward atmospheric events had several effects: economic – roads, foot-bridges, electrical and telecommunication lines, households, social and economic units, croplands; social – panic among the population, a slowdown of development rates in the affected zones, diminution of the population’s income; ecological – environmental degradation, surface and ground water pollution, excess humidity and degradation of slopes; indirect effects – costs of defence during the events and of return to normal life in their aftermath. Operative measures taken during the events: the informational system of the Alba County Operational Centre for Emergency Situations was activated: primary data on the evolution of phenomena were centralized by the corresponding institutions; affected areas were surveyed; immediate intervention measures and responsibilities were established; people were evacuated in special locations; medical assistance in case of necessity; warnings against polluted drinking water and supplies of mineral water; sanitary and veterinary anti-epidemic measures; traffic restrictions in the affected areas, etc. The following institutions, public services and economic agents assigned defence tasks against flooding were involved: ‘Unirea’ Inspectorate for Emergency Situations, Alba County; County Police Inspectorate; County Military Police Inspectorate (Gendarmery); Red Cross; Public Health Direction and other profile institutions.

Conclusions A basic component of the risk entailed by exposure to extreme natural phenomena is human society who bears and assesses their consequences. Defining the consequences may contribute to anticipating losses and lay down risk management regulations. The study region suffered severe damage, worsely affected being the road infrastructure, the hydrotechnical constructions, the socio-economic units, electrical and telephone networks and the agriculture. According to the ‘Unirea’ Inspectorate for Emergency Situations statistical records of interventions to limit and remove flood effects over the past decade, the year 2005 alone represented 44% of all situations, a very great percentage, indeed. Looking at the period of the year, when extreme negative phenomena occur, it appears that June and July register the highest frequencies, as torrential rainfall often triggers flood events. However, March and April, when snowmelt is associated with heavy rains, also may record vast flooding episodes and significant losses. Our findings have revealed that most of the floods triggered by meteorological phenomena of great intensity over short periods of time occurred in catchment basins and gully-affected areas. The map synthetising the 2002-2006 case-studies reveals that the effects of atmospheric risk phenomena in the Mureş Corridor and the Alba Iulia – Turda Depression have distinctively different frequency and intensity of occurrence, the most affected sector extending between Aiud and Alba Iulia cities. What explains it is the fact that the reception basins of the Mureş tributaries in this sector are larger, developing in the Trascău Mountains and the Aiud Hills; besides, the great level difference between source and mouth contributes to the accumulation of huge quantities of water and material from the slope into the channel, moreover so as large, formerly forested areas have been cleared off. Limiting these negative effects would require the afforestation of slopes in the affected drainage basins, the building of dams or wire-netting of gully-affected areas, works of consolidation of roads or even changing their layout if running in the proximity of watercourses.

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