BALWOIS 2004 Ohrid, FY Republic of Macedonia, 25-29 May 2004

THE INFLUENCE OF THE CLIMATICAL, PSYHICAL AND GEOGRAPHICAL FACTORS GENERATING FLOODS IN THE SMALL HIDROLOGICAL BASINS LOCATED IN THE WESTERN PART OF THE CARPATHIAN MOUNTAINS

Felicia POPOVICI NATIONAL INSTITUT OF HIDROLOGY AND WATER MANAGEMENT Bucharest,

Abstract The purpose of this paper is to present the influence of the climatic, physical and geographical factors (precipitations, geology, soil, vegetation, anthropogenic impact) to the maximum discharge, factors who generate the floods in small basins situated in the west part of Oriental Carpathians, Romania. For the period of study (1975 – 2000), is very important to analyse: - the maximum discharge which are produced; - the more important elements of floods; - the characteristics of the precipitations and runoff coefficients which are produced in the basins considered.(Gurghiu, Tarnave, Sovata, Bistra , Hodos, si , Rastolita.) Tables and graphics are coming to illustrate with accuracy the relationships between the characteristics of the rainfalls and geographical conditions of the main floods produced in these basins. The reason of these analyse is to determine useful parameters for the prediction and forecast of the floods in small basins, because these basins have a high speed reaction to the inputs elements (precipitations and its characteristics).

Geological conditions From the paleo-geographical evolution standpoint, the studied zone is characterized by a late magmatism manifested along the great transversal fault Oas – Tusnad, since Miocene to Pleistocene. The most intense and recent volcanic activity has been recorded in the Caliman-Harghita area. The eruptions occurred within the inferior Pliocene-Pleistocene cycle, when the volcanic structures erected. The strato-volcanic structure ( made of lava and piroclastite ) prevails among the specific effusion structures. In the eastern part of the Transilvanian Depression (upper reach of Mures and rivers) there are isolated sedimentary basins, namely the depressions of volcanic barrage ( dam ) Giurgeu and Ciuc. We can observe the geology of zone in the following map: (Fig 2)

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Legend: A = TOPLITA B = RASTOLITA C = BISTRA D = GURGHIU E = TARNAVA MICA F = SOVATA G = TARNAVA MARE H = SICASAU I = HODOS J=HOMORODUL MARE K = HOMORODUL MIC

Sedimentary formations

Aluvial deposits Pannonian (Pn) Extracarpathian Sarmatian (Sm) Andesits, Piroclastits Diorits and Basalts Upper Precambian (B)

Figure 2 – Geological Map (after Romanian Atlas 1978)

Lithological structure The studied volcanic area contains mainly impermeable or weakly permeable rocks. It is characterized by an intense drainage of the surface and shallow ground waters, due to the great slopes. In the compact volcanic area (andesites, basalts) the water resources are low, however the piroclastites offer great possibilities of water retention (when their stratification includes clays and cemented rocks). The regeneration of the shallow waters is more intense on the western slopes of the western Carpathian Mountains (rich precipitations).

Psyhical and geographical conditions

Relief The volcanic relief of the studied area is distinguished by successive eruptions and has both petrographical and structural character. It has specific shapes generated either by the various agglomerations of lava reaching the surface, or by the direction of the various erosions within the volcanic skeleton. The andesites lava (hard and compact, sometimes with stratification) shows as dome shapes, while the volcanic agglomerations show as plateaus generating a more varied relief, alike to the one formed by conglomerates ( scarps, towers,needles ). The volcanic chain Oas - Caliman – Harghita (considered as the longest of Europe) has a variety of relief forms, due to the mineralogic composition of the rocks, to the eruption type or to the age of the

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volcanos. The wide plateau in contact with the Precarpathic Transilvanian area, is dominated by associated domes, made of an alternation of andesite and piroclastite lavas with more pronounced slopes and monoclinal stratification. On top, the central part of these domes corresponds to the volcanic craters. The alteration process of the feldspats contained in the andesites has created pans and lapies on some surfaces and the more intensive kaolinization allowed small depressions to be formed, of doline type. In the Caliman Mountains, there are caves with lymonitic structures ( stalactites, stalagmites and drip curtains ) and in the Caliman - Gurghiu - Harghita (1.600 - 2.100 m) group, the best preserved morphology is the volcanic one. From the structural standpoint, the area has two complex parts: the volcanic-sedimentary base ( Pliocene ) due to the accumulation of volcanic products, and the upper part represented by volcanic cones formed during the last phase of the volcanic erruptions. Legend: A = TOPLITA B = RASTOLITA C = BISTRA D = GURGHIU E = TARNAVA MICA F = SOVATA G = TARNAVA MARE H = SICASAU I = HODOS J = HOMORODUL MARE K = HOMORODUL MIC

RELEF DEVELOPED ON THE VULCANO FORMATIONS Mountains (1600-1900m)→on vulcano neogen formations:volcano cones, craters. Mountains (800-1200m)→from defragmentation of the piroclastites plateaus and neogene lava INTERMOUNTAIN DEPRESSION Tectonics and volcanic barrage depression with hill aspect or aluvial plateau aspect RELIEF OF HILLS AND PLATEAUS Relief developed on the neozoic monoclinale formations or affected by diapires folds and domes Hills (400-700m)proceeding by the fragmentation of the plateau with actifs versants Relief developed on the neogene and sedimentary formations very strong affected by folds, with accentuate tectonic mobility. Hills (400-900m) fragmentated in summits and massifs which are liable to the denudation SUBCARPATHIANS DEPRESSIONS AND HILLS DEPRESSIONS Differential erossion depressions with hilly aspect

Figure 3 – Geomorphologiclal Map (after Romanian Atlas 1976)

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The erosion has formed countless depression basins, often represented by relief inversions.The valleys from the western part of the Carpathians are narrow, with pronounced slopes and irregular longitudinal profile; the main valleys are wider, having flood plains and terraces in the rocks or in alluvial deposits, while the largest valleys have an either longitudinal development ( Mures and Olt in the Giurgeu Depression and Ciuc Depression) or cross sectors with local narrowings, straits and gorges.( Mures in the Toplita – Deda Strait ). The highest go from 1750-2100m : Pietrosu Peak, in the Calimani Mt 2.102m, Saca Peak in Gurghiu Mt, 1.777m and Harghita Madaras Peak, in Harghita Mt. -1800m. In the next picture - Fig 3 – is attached the geomorphological map (after Romanian Atlas 1976) for more details.

Soil The soils of the mountain area Caliman – Gurghiu - Harghita have been formed in a wet and relatively cold climate; they have a generally small depth and a more or less skeleton character. The main feature of the soil cover is the vertical division into zones; however this succession of altitudes, determined by the climate, is much influenced by rocks and relief. The studied area represents the domain of the brown – acid soils and andosols. In the lower part of the mountain, corresponding to the area of the leafy trees or mixture ( leafy and coniferous ), there are brown soils, as well as brown slightly debasified soils, rendzinas, lithosols. In the upper part of the mountain, specific area of the coniferae and sub-alpine zone ( juniper area ), brown-acid and brown podzolic soils can be found, along with the andosols, and over restricted areas, there are lithosols as well. In the depression area constituting the transition to the Transilvanian sub-Carpathians ( lower Gurghiu valley, Praid-Sovata, Odorhei, Homoroadelor corridor ) there is a large variety of soils. The highest areas have brown soils (slightly and moderately debasified), brown-luvic, white luvic soils, while the low plains and the weakly drained flood plains have alluvial soils in various degrees of gleyzation – due to the high humidity, peat soils and humic gley.) In the Fig 4 is the map of the soils, which are showing the types of the soils for the area studied. The map was realised after Romanian Atlas –1978.

Vegetation The analyzed hydrological basins are vertically divided into zones according to the vegetation structure. The vegetation - especially the forest – has a very important role in the process of the runoff generation : the arborescent vegetation helps forming more permeable soils than in the free areas ( lawns or reclaimed lands ). The vegetation has a direct influence on the soils endurance to erosion, both by the litter and by the roots knitting system maintaining the humidity from infiltrations. The forest creates a specific microclimate, characterized by the snow melting delay, thus increasing the period of the high waters along with the runoff decrease and intensification of infiltrations. Rivers regularization is carried out through the underground water supply, even during the periods without precipitations. On the deforested surfaces the phenomenon happens in the reversed way. In the Fig 5 is the map of the vegetation –forests-after Romanian Atlas –1975 at scale 1:1.000.000

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Legend:

A = TOPLITA B = RASTOLITA C = BISTRA D = GURGHIU E = TARNAVA MICA F = SOVATA G = TARNAVA MARE H = SICASAU I = HODOS J = HOMORODUL MARE K = HOMORODUL MIC

CHERNOZEMS SOILS

Leached and rendzinas chernozems ARGILLUVIC SOILS

Brown-podzalic soils Lessivé soils and brown lessivé Lessivé soils Brown lessivé and planosols Planosols and argilluvic soils (including lessivé) CAMBIC SOILS Brown-podzolic Acid brown soils Brown soils (slightly and moderately debasified ) and lessivé Brown soils (slightly and moderately debasified),acid brown soils, and argilluvic soils (including lessivé ). Acid brown soils and andosols Acid brown soils and brown podzolic LITHOMORPHIC SOILS Rendzinas and brown podzolic HIDROMORPHIC SOILS

Humic-gley soils Low humic gley soils Black soils on clays and maris (including humic gley and brown soils),cambic chernozems in the humid zone and brown chernozems soils. NVOLUATED SOILS Aluvial soils and bed loan Figure 4. SOILS (after Romanian Atlas 1978)

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Legend: A = TOPLITA B = RASTOLITA C = BISTRA D = GURGHIU E = TARNAVA MICA F = SOVATA G = TARNAVA MARE H = SICASAU I = HODOS J = HOMORODUL MARE K = HOMORODUL MIC

Spruce fir forests [Picea abies (L.)Karst Mixed forests buch ;fir or beech fir and spruce fir(fir forest inclusive) Beech forests inclusive beechd sycomore mixed Forest linden, maple and ashtree- oaks Oaks forests mixing with sycomore maple. (Moldavia Plateau and Transilvanian Plateau)

Figure 5 Forest (vegetation) (After Romanian Atlas 1975)

Changes due to human activity

Deforestation The main human activity responsible for the break of the slopes stability is the land reclaiming by deforestation. Presently, the afforested land covers large areas within the analyzed basins, over 70 %, average ( Table 1). In these basins the defforestations have not modified the natural environment too deeply. There are large defforested areas at the sub-alpin level, the limit of which has been considerably decreased, as well as in the valley corridors and the depression basins, resulting in the extension of the pastures and various crops, around the inhabited areas. There are, however, areas where the massive defforestations have totally removed the forest, as in some sectors of the basins of Toplita, Homorodul Mare and Homorodul Mic ( the afforested areas cover 25-30 % ), in the Hodos basin located in the hills area ( below 20 % ), thus leading to the break of the slopes balance followed by various phenomena. The development of the inhabited areas along the main valleys which have gradually reached a compact structure and an irregular texture, especially on the Gurghiului, Tarnave and Homoroadelor valleys, also lead to the development of narrow streets along the slope. The extension of the inhabited areas on the slopes, especially in the lower third of them, has been accompanied by defforestations, equalizations and division into sections, which determined an activity of the morphodynamic potential.

Hydrotechnical arrangements. In the hydrological basins analyzed in this paper, there are hydrotechnical arrangements such as dams and embankments. There are two dams with hydro-energetical and water supply purpose: Rastolita, on the Rastolita river ( tributary of the river Mures in the Toplita-Deda strait) and Sicasau, located at the confluence of the Tarnava Mare river with its tributary Sicasau. (Fig 1)

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The embankments can be found in the inhabited areas, especially on the lower reach of the two Tarnava rivers, as well as on the Sovata, Gurghiu and Toplita rivers. The embankment works along the river bed generate important changes, both of the discharges and of the water level, compared to the regime prior to their execution. Data concerning the morphometry of the studied areas and a synthesis of the climatic elements acting in the area can be seen in the tables 1 and 2.

Table 1 Morphometry data and coefficients of afforestation

River-Hydrometric station F Hav Basin altitude Lr Ir Ib Cf (km2) (m) (km) (‰) (‰) (%) max min Toplita - Toplita 208 1149 2021 652 28,7 42 256 36.5 Rastolita- Rastolita 163 1174 1998 513 18,2 35 265 76.6 Cofu -Bistra 19,7 1277 1520 800 9.0 71 303 99 Valea de Mijloc- Bistra 16,1 1258 1550 800 7.0 88 320 92 Stegea -Bistra 10,2 1235 1460 800 6.0 101 304 96 Donca- Bistra 22,8 1113 1420 800 8.0 93 305 95 Bistra –Bistra 91,9 1104 1550 575 22.0 38 310 74 Gurghiu –Lapusna 109 1202 1777 809 10,1 39 256 67.9 Gurghiu –Ibanesti 404 1036 1777 475 34,0 23 226 79 Gurghiu–Solovastru 550 925 1777 400 55,0 20 218 70.1 Sacadat- Sacadat 7,5 741 1050 550 3.1 16 81 10 Nitra - Sacadat 1,9 870 1050 540 3.1 222 239 39 Silvas - Sacadat 5,9 693 890 530 4.3 84 148 31 Sacadat CFR-am.Sovata 37,8 727 1050 500 6.1 18 134 50 Sovata-Sovata Scoala 37,3 1107 1776 500 15.2 65 257 81 Sovata-am.Tarnava Mica 83,8 872 1776 435 17.5 53 233 66 Tarnava Mica- Sarateni 454 913 1777 409 29,5 32 210 50.7 Tarnava Mare- Varsag 112 954 1577 661 18,0 50 145 54.3 Tarnava Mare- Odorhei 645 925 1801 472 46,5 21 190 44.4 Sicasau - Sicasau 147 1025 1694 698 15,0 33 225 54.6 HomorodulMare-Baile 153 720 1685 481 27,2 30,8 140 21.9 HomorodulMare-Sanpaul 40,0 954 1685 701 6,2 99,8 215 31,4 HomorodulMic- Capalnita 7,3 1006 1363 639 10,1 45,6 128 23,7 Homorodul Mic – 34,2 836 1363 603 19,2 25,9 118 22,9 Hodos –Ulies 14,7 649 775 538 8.1 21.0 125 18 Hodos – Nicolesti 24,0 620 830 476 6.0 17.9 132 16 Blond-Nicolesti 21,7 627 830 476 6.0 41.7 145 9

Talbe 2 Synthesis of climatic parameters Subalpine area Mountain forest area Climatic parameters (1.600 - 2.102 m) (under 1.600 m ) Annual average temperature (°C) +2 ... -2 2 - 6 Average temperature-july (°C) 8 - 14 14 - 18 Average temperature-january (°C) -8 ... -10 -4 ... -8 Annual average amplitude (°C) 17 - 20 21 - 22 Maximum absolute temperature (°C) 20 - 22 30 - 32 Minimal absolute temperature (°C) -34 ... -38 -33 ... -34 Days with frost > 140 110 - 130 Summer days - 0 - 20 Tropical days - 1 - 8 Annual average humidity > 85 > 80 Annual average nebulousness 6,0 - 7,0 5,7 - 6,0 Clear days < 40 40 - 50 Cloudy days 120 - 150 100 - 120 Annual precipitation amount 1.000 - 1.400 850 - 1.000 Precipitations during the warm season 500 - 650 450 - 500 Maximum precipitations in 24 hours 80 - 200 80 - 200 Days with precipitations 150 - 175 140 - 150 Days with snow layer o 100 - 200 80 - 95 Decadal average depth of the snow layer 50 - 100 cm ( third ten-day of the months February and March, or the first ten-day period of April ) Absolute depth of the snow layer 200 - 350 cm Aridity value > 50 40 - 50

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AREALS

The climate of mountains with H>1700m The climate of mountains with H=800m The climate of mountains with H<800m

Figure 6 - climatic regionalisation (after Romanian Atlas 1979)

1

2

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3 Figure 7 – 1.Nebulosity; 2 Sunshine Duration; 3 Global radiation. (After Romanian Atlas,1972)

The number of the days with the precipitations>0,1mm

Annual Precipitation (mm) Legend: 1400 A = TOPLITA 1200 B = RASTOLITA 1000 C = BISTRA 800 D = GURGHIU E = TARNAVA MICA 700 F = SOVATA 600 G = TARNAVA MARE H = SICASAU 500 I = HODOS J = HOM0ORODU MARE K = HOMORODU MIC

Figure 8 - The map with the precipitation (after Romanian Atlas 1975)

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Hot season

Cold season

The number of days with snow layer Figure 9 The precipitations on the seasons (after Romanian Atlas 1979)

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Maximum runoff-floods

Maximum discharges The source of the high waters and floods generates some peculiarities in their occurrence, evolution and repartition. On the rivers with a small surface of the reception basins such as : Sacadat – Sacadat (7,5 km2), Nitra – Sacadat (1,9 km2) , Silvas – Sacadat (5,9 km2) , Hodos–Ulies (14,7 km2 ) , the torrential rains produce the greatest discharges, while in case of the bigger basins - Tarnava Mare- Odorhei (645 km2), Tarnava Mica-Sarateni (454 km2) the effect of the pouring rains decreases significantly as the role of the long period rains and the snow melting increases. It is hard to include the origin of the maximum discharges in categories (such as generated by rains, snow melting or of mixed origin), especially for the periods with snow layer when the analysis of the origin is mandatory, using the separation of sources on the chronological graphics for daily average discharges, also using similar graphics for precipitations, snow layer and air temperature. Within the category of the maximum discharges of rain origin, the maximum discharges coming from the rainfalls during the warm time of the year (V-XI) are included. The maximum discharges of snow melting origin include the maximum discharges occurred during the months XII-IV, when sudden snow melting may occur due to positive temperatures of the air and when the liquid precipitations have been totally absent or have had a low contribution compared to the water layer coming from the snow melting. Within the category of the maximum discharges of combined origin, the maximum discharges are included, which occur generally within the winter – springtime period, when along with the snow melting liquid precipitations fall as well, each of the two sources having significant contribution in the maximum discharge occurrence. As concerning the amount of the annual maximum discharges (Table 3) in most of the cases those coming from rainfalls are considerably higher than those coming from snow melting and higher than the combined ones as well.

Table 3 The highest maximum discharges occurred on the studied rivers within the observation period Qmax Nr. River-Hydrometric Period of F H registered Data crt. station observations ( km2 ) (m) (m3/s) of records

1 Toplita - Toplita 1954 - 1999 208 1149 89.0 17.II.1958 2 Rastolita - Rastolita 1954 - 2000 163 1174 110 13.V.1970 3 Cofu -Bistra 1975 - 2000 19,7 1277 11.4 6.IV.2000 4 Valea deMijloc- Bistra 1975 - 2000 16,1 1258 9.6 6.IV.2000 5 Stegea -Bistra 1975 - 2000 10,2 1235 5.56 6.IV.2000 6 Donca- Bistra 1975 - 2000 22,8 1113 19.3 6.IV.2000 7 Bistra –Bistra 1975 - 2000 91,9 1104 88.8 6.IV.2000 8 Gurghiu –Lapusna 1980 - 2000 109 1202 32.5 27.XII.1995 9 Gurghiu –Ibanesti 1986 - 2000 404 1036 199 27.XII.1995 10 Gurghiu –Solovastru 1953 - 1998 550 925 271 12.III.1981 11 Sacadat- Sacadat 1975 - 2000 7,5 741 14.0 3.V1978 12 Nitra - Sacadat 1975 - 2000 1,9 870 2.22 2.VII.1975 13 Silvas - Sacadat 1975 - 2000 5,9 693 8.95 12.III.1981 14 Sacadat CFR – 1975 - 2000 37,8 727 46.7 2.VII.1975 am.Sovata 15 Sovata-Sovata Scoala 1975 - 2000 37,3 1107 24.0 2.VII.1975 16 Sovata-am.Tarnava 1975 - 2000 83,8 872 46.8 15.V.1984 Mica

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17 Tarnava Mica- 1951 - 2000 454 913 323 13.V.1970 Sarateni 18 Tarnava Mare- Varsag 1964 - 2000 112 954 81.5 13.V.1970 19 Tarnava Mare- 1950 - 2000 645 925 205 13.V.1981 Odorhei 20 Sicasau - Sicasau 1950 - 2000 147 1025 29.3 6.IV.2000 21 Homorodul Mare- 1970 - 2000 358 621 82.0 1.VIII.1970 Baile Homorod 22 Homorodul Mare- 1952 - 2000 153 720 82.0 31.III.1952 Sanpaul 23 Homorodul Mic - 1959 - 2000 7,3 1006 16.0 28.VII.1982 Capalnita 24 Homorodul Mic –Lueta 1974 - 2000 34,2 836 39.5 2.VII.1975 25 Hodos –Ulies 1975 - 2000 14,7 649 72.6 6.VII.1975 26 Hodos – Nicolesti 1975 - 2000 24,0 620 117 2.VII.1975 27 Blond-Nicolesti 1975 - 2000 21,7 627 216 10.III.2000

The maximum discharges with various exceeding possibilities (Table 4) have been calculated using the classical methodology of statistical processing, based on determining the average maximum discharge Qmax, Cv and Cs and tracing the empirical and theoretical ensurance curves for all the considered rivers.

Table 4 Maximum discharges with various exceeding probabilities

Maximum annual discharges of q1% various ensurance (probability) (l/skm2) River-Hydrometric station Observations F H (m) degrees period ( km2 ) 1% 3% 5% 10%

Toplita - Toplita 1954 - 1999 208 1149 98.7 73.5 62.1 46.9 474 Rastolita - Rastolita 1954 - 2000 163 1174 125.7 93.5 78.9 59.5 771 Cofu -Bistra 1975 - 2000 19,7 1277 16.7 12.3 10.3 7.67 847 Valea deMijloc- Bistra 1975 - 2000 16,1 1258 15.5 11.3 9.32 6.83 962 Stegea -Bistra 1975 - 2000 10,2 1235 6.69 5.07 4.33 3.33 655 Donca- Bistra 1975 - 2000 22,8 1113 23.6 17.5 14.7 11.0 1035 Bistra –Bistra 1975 - 2000 91,9 1104 108.2 77.7 63.0 45.3 1177 Gurghiu –Lapusna 1980 - 2000 109 1202 43.4 32.6 27.7 21.1 398 Gurghiu –Ibanesti 1986 - 2000 404 1036 353.5 251.0 200.4 140.9 875 Gurghiu –Solovastru 1953 - 1998 550 925 313.0 232.8 196.5 147.9 569 Sacadat- Sacadat 1975 - 2000 7,5 741 18.9 12.9 9.3 5.8 2520 Nitra - Sacadat 1975 - 2000 1,9 870 2.48 1.72 1.31 0.86 1305 Silvas - Sacadat 1975 - 2000 5,9 693 12.1 8.26 5.94 3.66 2051 Sacadat CFR – am.Sovata 1975 - 2000 37,8 727 66.8 46.8 36.5 24.9 1767 Sovata-Sovata Scoala 1975 - 2000 37,3 1107 36.4 25.8 20.5 14.3 976 Sovata-am.Tarnava Mica 1975 - 2000 83,8 872 80.7 59.9 50.5 37.9 963 Tarnava Mica- Sarateni 1951 - 2000 454 913 376.3 267.7 214.5 151.4 829 Tarnava Mare- Varsag 1964 - 2000 112 954 101.1 73.5 60.5 44.1 902 Tarnava Mare- Odorhei 1950 - 2000 645 925 238.6 183.0 157.2 122.7 370 Sicasau - Sicasau 1950 - 2000 147 1025 41.2 32.1 27.9 22.2 280 Homorodul Mare- Homorod 1955 - 1994 40 954 84.5 58..3 44.0 28.9 2112 Homorodul Mare- Sanpaul 1952 - 2000 153 720 114.0 86.3 73.7 56.6 745 Homorodul Mic - Capalnita 1959 - 2000 7,3 1006 19.6 13.6 10.5 6.96 2685 Homorodul Mic –Lueta 1974 - 2000 34,2 836 77.4 52.9 38.8 24.5 2263 Hodos –Ulies 1975 - 2000 14,7 649 33.9 23.7 18.6 12.7 2306 Hodos – Nicolesti 1975 - 2000 24,0 620 109.5 73.2 54.5 33.5 4563 Blond-Nicolesti 1975 - 2000 21,7 627 109.8 76.9 59.9 41.0 5060

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From the analysis of annual maximum specific discharges of 1 % ensurance -probability, the conclusion results that the highest values, of 4-5000l/s km2 have been obtained for relatively small surfaces, contained within 5-30 km2 in the Sovata and Hodos basins. The lowest values of the annual maximum specific discharges of 1 % ensurance, of about 300 l/s km2 have been obtained on rivers with large basin surfaces: Tarnava Mare- Odorhei, Gurghiu –Solovastru.

Hydrographs for floods and high waters Taking into account the time distribution of the precipitations and the time for the water to cross the respective basin, the floods can have only one main peak and a couple of non-essential peaks, or several main peaks with secondary peaks inserted between them. The high spring waters have a longer duration and less emphasized peaks. The most important flood waves, as concerning the maximum discharges recorded on the rivers in the analyzed area, are the singular flood waves. As far as the number of floods in one year is concerned, this is variable from one year to the other, but the average number of floods is 6-7 (Table 5). Out of these ones, 3-4 occur during the spring time or at the beginning of summer, coinciding with the period of high waters ; the less floods occur during winter, around 1-2, or totally missing, in some years.

Table 5 Records of the highest floods during the period 1975-2000

Nr. River / hydrometric Year F H Qmax qmax Date of Type of flood crt. station (km2 ) (cm) (m3/s) (l/skm2 ) occurrence

1 Toplita - Toplita 1995 208 179 53.1 255 12XII-5.I rain-snow. c 2 Rastolita - Rastolita 1995 163 242 76.2 467 23XII-4.I rain-snow. c 3 Cofu -Bistra 2000 19,7 194 8.30 421 5-9 IV only rain 4 Valea deMijlocBistra 2000 16,1 195 7.78 483 5-9 IV only rain 5 Stegea -Bistra 2000 10,2 148 2.60 255 5-9 IV only rain 6 Donca- Bistra 2000 22,8 142 7.70 338 5-9 IV only rain 7 Bistra –Bistra 2000 91,9 184 44.1 480 5-9 IV 8 Gurghiu –Lapusna 1995 109 185 42.2 387 21XII /10.I rain-snow. c 9 Gurghiu –Ibanesti 1995 404 325 199 492 22XII- 6.I rain-snow. c 10 Gurghiu –Solovastru 1995 550 186 271 405 4.III –7.IV rain-snow. c 11 Sacadat- Sacadat 1984 7,5 143 5.76 768 13V-21V only rain 12 Nitra - Sacadat 1984 1,9 132 0.675 355 13V-21V only rain 13 Silvas - Sacadat 1984 5,9 163 6.07 1029 13V-21V only rain 14 Sacadat CFR – 1984 37,8 189 21.2 561 13V-21V only rain am.Sovata 15 Sovata-SovataSc 1984 37,3 175 17.2 461 13V-21V only rain 16 Sovata-am.Tarnava 1984 83,8 192 46.8 558.5 13V-21V only rain Mica 17 Tarnava Mica- Sarateni 1975 454 357 223 491 2-7 VII only rain 18 Tarnava Mare- Varsag 1975 112 270 54.2 484 1-15 VII only rain 19 Tarnava Mare- Odorhei 1981 645 300 205 318 8 III- 4 IV rain-snow.s 20 Sicasau - Sicasau 1995 147 360 76.2 518 23 XII-6 I. rain-snow.s 21 Homorodul Mare-B. 1980 40.0 350 82 2050 26VII-6VIII only rain Homorod 22 Homorodul Mare- 1984 153 380 65.6 428 13-20.V only rain Sanpaul 23 Homorodul Mic - 1982 7,3 300 16 2191 28VII-1VIII only rain Capalnita 24 Homorodul Mic –Lueta 1975 34,2 325 37.8 1105 14-18.V only rain 25 Hodos –Ulies 1975 14,7 395 71.6 4870 2-3VII rain c 26 Hodos – Nicolesti 1975 24,0 519 117 4875 2-3VII rain c 27 Blond-Nicolesti 1975 21,7 493 94.5 4355 2-3VII rain c

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Qmax=71.6 m³/s q=4870 l/s/km² Tc=1h30min Tt = 9h15min γ =0.312 W = 730.8(x10³m³) hs =49.7 (mm)

Qmax=117 m³/s q=4875 l/s/km² Tc=2h15min Tt =11h30min γ=0.221 W =1062(x10³m³) hs =44.2 (mm)

Qmax=94.5 m³/s q=4355 l/s/km² Tc=1h30min Tt =9hours γ =0.349 W =1035(x10³m³) hs =47.7 (mm) x=72.1mm

Figure 10 Flood hodos 2-3 VII. 1975

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BALWOIS 2004 Ohrid, FY Republic of Macedonia, 25-29 May 2004

Qmax= 11.4m³/s q=600/skm² Tc=16hours Tt =96hours γ =0.2 W=792(x10³m³) hs =40.2 mm X=70.5 mm

Qmax= 9.66m³/s q= 603.8 l/skm² Tc=16hours Tt =96hours γ =0.22 W=748(x10³m³) hs =46.5 mm X=73.0 mm

Qmax=5.56 m³/s q= 617.8l/skm² Tc=16hours Tt =96hours γ =0.24 W=461(x10³m³) hs =45.2mm X=72.5 mm

Droughts and Floods 15

BALWOIS 2004 Ohrid, FY Republic of Macedonia, 25-29 May 2004

Qmax= 19.3m³/s q= 839.1 l/skm² Tc=16hours Tt =100hours γ =0.21 W=1440(x10³m³) hs =63.2 mm X=70.5 mm

Qmax= 88.1m³/s q= 965.2 l/skm² Tc=18hours Tt =11hours γ =0.1 W=3.6(x10³m³) hs =39.2 mm X=52.6 mm

Figure 11 Flood Bistra 5- 8 IV 2000

Table 6 Table with the wav elements characteristic to the highest recorded floods Nr. Crt River / hydrometric Date of Maximum Characteristic elements of the floods station occurrence F recorded discharge 2 (km ) Q q Tc Tt γ W hS (m³/s) (l/s/km² (ore) (ore) (10³m³ (mm ) ) ) 1 Toplita - Toplita 12XII-5.I 1995 208 53.1 255 5330 230 0.26 11.455 55.1 2 Rastolita - Rastolita 23XII-4.I 1995 163 76.2 467 28 119 0.26 8.532 52.. 3 3 Cofu -Bistra 5-8 IV 2000 19,7 11.4 600 16 96 0.20 792 40.2 4 Valea deMijloc- Bistra 5-8 IV 2000 16,1 9.66 603.8 16 96 0.22 748 46.5 5 Stegea -Bistra 5-8 IV 2000 10,2 5.56 617.8 16 96 0.24 461 45.2 6 Donca- Bistra 5-8 IV 2000 22,8 19.3 839.1 16 100 0.21 1440 63.2 7 Bistra –Bistra 5-8 IV 2000 91,9 88.8 965.2 18 112 0.10 3.600 39.2 8 Gurghiu –Lapusna 21XII-10.I 109 42.2 387 53.5 230 0.27 9.432 86.5 1995 9 Gurghiu –Ibanesti 22XII- 6.I 1995 404 199 492 44 188 0.27 36.360 90.0 10 Gurghiu –Solovastru 4III-7 IV 1981 550 271 493 79 340 0.27 89.683 163

Droughts and Floods 16

BALWOIS 2004 Ohrid, FY Republic of Macedonia, 25-29 May 2004

11 Sacadat- Sacadat 13-21V 1984 7,5 5.76 768 19 87 0.23 417 55.6 12 Nitra - Sacadat 13-21V 1984 1,9 0.675 482 1915 101 0.24 57.6 30.3 13 Silvas - Sacadat 13-21V 1984 5,9 6.07 1029 1930 115 0.17 414 70.2 14 Sacadat CFR – 13-21V 1984 37,8 21.2 561 20 120 0.20 1.915 50.7 am.Sovata

15 Sovata-Sovata Scoala 13-21V 1984 37,3 17.2 461 2030 125 0.19 1.440 38.6 16 Sovata-am.Tarnava 13-21V 1984 83,8 46.8 558.5 21 136 0.18 4.032 48.1 Mica

17 Tarnava Mica- 2-7 VII 1975 454 223 491 33 142 0.29 33.256 73.2 Sarateni 18 Tarnava Mare- Varsag 1-9 VII 1975 112 54.2 484 32 137 0.25 6.685 59.7 19 Tarnava Mare- 8III-4IV 1981 645 205 318 90 391 0.27 78.105 121 Odorhei 20 Sicasau - Sicasau 23XII-6I 1995 147 76,2 518 54 232 0.25 15.962 109 21 Homorodul Mare- 26.VII-6VIII/ 40,0 82.6 2050 20 85 0.27 6.817 170 B.Homorod ‘80

22 Homorodul Mare- 13-20V 1984 153 65.6 428 30 127 0.27 8.100 52.9 Sanpaul

23 Homorodul Mic - 28 VII-1VIII/ 7,3 16.0 2190 6 26 0.28 426 58.4 Capalnita ’82

24 Homorodul Mic –Lueta 14-18 V 1984 34,2 37.8 1105 4 16 0.27 2.105 61.5 25 Hodos –Ulies 2-3VII 1975 14,7 71.6 4870 130 915 0.312 730.8 49.7 26 Hodos – Nicolesti 2-3VII 1975 24,0 117 4875 215 1130 0.221 1.062 44.2

Table 7 Table with the main parameters of the runoff for the representative basins River / Nr. F H Q q hS hydrometric 2 x α Crt (km ) (m) (m³/s) (l/s/km²) (mm) station 1 Cofu -Bistra 19,7 1277 11.4 600 40.2 70.5 0.59 Valea deMijloc- 2 16,1 1258 9.66 603.8 46.5 73.0 0.64 Bistra 3 Stegea -Bistra 10,2 1235 5.56 617.8 45.2 72.5 0.71 4 Donca- Bistra 22,8 1113 19.3 839.1 63.2 63.0 0.99 5 Bistra –Bistra 91,9 1104 88.8 965.2 39.2 52.6 0.74 Sacadat- 6 7,5 741 5.76 768 55.6 90.0 0.62 Sacadat 7 Nitra - Sacadat 1,9 870 0.675 482 30.3 65.7 0.46 8 Silvas - Sacadat 5,9 693 6.07 1029 70.2 92.0 0.76 Sacadat CFR – 9 37,8 727 21.2 561 50.7 88.6 0.57 am.Sovata Sovata-Sovata 10 37,3 1107 17.2 461 38.6 62.0 0.62 Scoala Sovata- 11 am.Tarnava 83,8 872 46.8 558.5 48.1 85.0 0.56 Mica 12 Hodos –Ulies 14,7 649 71.6 4870 49.7 80.0 0.621 Hodos – 13 24,0 620 117 4875 44.2 76.0 0.581 Nicolesti 14 Blond-Nicolesti 21,7 627 94.5 4355 47.7 72.0 0.662

Droughts and Floods 17

BALWOIS 2004 Ohrid, FY Republic of Macedonia, 25-29 May 2004

Reference DIACONU C., (1972) : Criterions of selection for the studys sections in the experimental, Hidrologcal Study, XXIX, N.I.M.H., Bucharest. DONISĂ I., (1968) : Geomophology of the BistriţValley, Academy Publishing House, Bucharest. GASTESCU P., (1998), Hydrology, Roza Vanturilor-, Publishing House, Targoviste. GASTESCU P., ZAVOIANU I., (1998):An the genesis and time space distribution of water resources in Romania.Geographical aspects.RRG.42. MIHĂILESCU V., (1969) : The Physic Geography of Romania,Scientific Publishing House, Bucharest. MITA P., (1973) : The cantitative inffluence of the forests to the floods, Hidrologcal Study, XLI, N.I.M.H., Bucharest. MITA P., (1983) :General influences of the precipitations fall down concerning the forests, Hidrologcal Study,LV, N.I.M.H. Bucharest. MITA P., MUSCANU M., (1986) : The coeficient runoff in small basins, Hidrologcal Study, LIII,N.I.M.H, Bucharest. MUSCANU M., (1984) : Relation betwen duration and the intensity of the rain, XLVI. N.I.M.H, Bucharest. MUSTAŢĂ L., (1970) : Studys about occurancy of the runoff in Suha- representativ basin. Hidrologcal Study, XXVIII,N.I.M.H, Bucharest. MUSTAŢĂ L., (1979) : Maximal runoff on the small river, Hidrologcal Study, N.I.M.H., Bucharest MUSTAŢĂ L., (1980) :The first results on the experimental stations and representativ basins,XLIX, Hidrologcal Study, N.I.M.H., Bucharest. NAUM TR., (1983) : The Morphology of the Caliman Summit, Annals of University Bucharest. PLATAGEA GH. & co., (1966) : The parameters of the torrential rains used in the hydrological calculations concerning maximal runoff, , Hidrologcal Studys, I.S.C.H., XVIII. ROSU A., (1980 ), The Physic Geography of Romania,Education Publishing House, Bucharest. SHREIBER W., (1994):Harghita Mountains- Geomorphological Study, Academy Publishing House, Bucharest. UJVARI I., (1959 ), Hidrography of R.P.R, Scientific Publishing House, Bucharest. UJVARI I., (1972) : Romanian river’s geography, Scientific Publishing House, Bucharest. ZAVOIANU I., ( 1978 ) : The morphometry of hydrographical basins. Scientific Publishing House, Bucharest XXX ( 1960) :Geographic monography of R.P.R., Academy Publishing House, Bucharest. XXX ( 1962 - 1964) : The climate of R.P.R., Institut of Meteorology, Bucharest. XXX ( 1966 ) : Climatologic Atlas of R.P.R., Institut of Meteorology, Bucharest. XXX (1971) : The rivers of Romania, hydrological monography N.I.M.H.,Bucharest XXX (1983) Romanian Geography, vol.I , Institut of Meteorology, Bucharest, Academy Publishing House, Bucharest XXX (1987), Romanian Geography, vol.III , Institut of Meteorology, Bucharest, Academy Publishing House, Bucharest XXX (1974 ), Atlas of R.S. Romania, Academy Publishing House, Bucharest XXX (1980 ), Studys and researches in hydrologyi, XLIX,NIMH, Bucharest. XXX Hydrological annuars from the experimental stations and representativ basins, NIMH Bucharest.

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