 | |
| Continent | Europe |
|---|---|
| Region | Balkan Peninsula,Southeast Europe |
| Coordinates | 42°45′N25°30′E / 42.750°N 25.500°E /42.750; 25.500 |
| Area | Ranked 103rd |
| • Total | 110,993.6[1] km2 (42,854.9 sq mi) |
| Coastline | 378 km (235 mi) |
| Borders | 1,867 km |
| Highest point | Musala,[2] 2,925 m (9,596 ft) |
| Lowest point | Black Sea, 0 m |
| Longest river | Iskar River, 368 km (229 mi) |
| Largest lake | Lake Burgas 27 km2 (10 sq mi) |
| Climate | temperate in north toMediterranean in south |
| Terrain | mountains and hills with lowlands in north and southeast |
| Natural resources | copper, lead,zinc, coal, timber, arable land |
| Natural hazards | earthquakes (in certain areas),floods,landslides |
| Environmental issues | air andwater pollution,deforestation, soil contamination[3] |
| Exclusive economic zone | 110,879 km2 (42,811 sq mi) |
Bulgaria is a country situated inSoutheast Europe that occupies the eastern quarter of theBalkan peninsula, being the largest country within its geographic boundaries. It bordersRomania to the north,Serbia andNorth Macedonia to the west,Greece andTurkey to the south, and theBlack Sea to the east. The northern border with Romania follows the riverDanube until the city ofSilistra. The land area of Bulgaria is 110,994[1] square kilometres (42,855 sq mi) (111,002[1] square kilometres (42,858 sq mi)), slightly larger than that ofCuba,Iceland or the U.S. state ofTennessee. Considering its relatively compact territorial size and shape, Bulgaria has a great variety of topographical features. Even within small parts of the country, the land may be divided into plains, plateaus, hills, mountains, basins, gorges, and deep river valleys. Thegeographic center of Bulgaria is located inUzana.
Bulgaria features notable diversity with the landscape ranging from the snow-capped peaks inRila,Pirin and theBalkan Mountains to the mild and sunnyBlack Sea coast and southernmost valleys; from the typicallycontinentalDanubian Plain (ancientMoesia) in the north to the strongMediterranean climatic influence in the valleys ofMacedonia and in the lowlands in the southernmost ofThrace, the lowest parts of theUpper Thracian Plain, along theMaritsa River, the SouthernBulgarian Black Sea Coast. Most of the country is situated within thehumid continental climate region, withAlpine climate in the highest mountains andsubtropical climate in the southernmost regions.[4]
The country has a dense river network but with the notable exception of the river Danube, rivers are mostly short and with low water flow.[5] The average annual precipitation is 670 mm; the rainfall is lower in the lowlands and higher in the mountains. The driest region isDobrudzha in the north-eastern part of the Danubian Plain (450 mm), while the highest rainfall has been measured in the upper valley of the riverOgosta in the western Balkan Mountains (2293 mm).[6]
Bulgaria has substantial land in agriculture and forest. In 2006land use andland cover was 5% intensive human use, 52% agriculture including pasture, 31% forest, 11% woodland-shrub, grassland, and non-vegetated, and 1% water.[7]
Phytogeographically, Bulgaria straddles theIllyrian andEuxinian provinces of theCircumboreal Region within theBoreal Kingdom. The country falls within six terrestrialecoregions of thePalearctic realm:Balkan mixed forests (main),Rodope montane mixed forests (main in themountains),Euxine-Colchic deciduous forests,Aegean and Western Turkey sclerophyllous and mixed forests,East European forest steppe andPontic–Caspian steppe.[8]
The borders of Bulgaria have a total length of 2,245 km; of them 1,181 km are land boundary and 686 km are formed by rivers. The coastline is 378 km.[9][10]
The northern border withRomania is 609 km. Most of the frontier (470 km) is formed by the river Danube from the mouth of the riverTimok in the west to the city ofSilistra in the east. The land border from Silistra to Cape Sivriburun at theBlack Sea is 139 km long.[9] The Danube, with steep bluffs on the Bulgarian side and a wide area of swamps and marshes on the Romanian side, is crossed by two bridges –New Europe Bridge betweenVidin andCalafat, andDanube Bridge betweenRuse andGiurgiu. There are 48 Bulgarian and 32 Romanian islands along the river Danube; the largest one,Belene (41 km2), belongs to Bulgaria.[11] The land frontier has three border crossings at Silistra,Kardam andDurankulak at the Black Sea. It is also crossed by a major gas pipeline transporting natural gas from Russia to Bulgaria.[11]
The eastern border (378 km) is maritime and encompasses theBulgarian Black Sea Coast from Cape Sivriburun in the north to the mouth of theRezovo River in the south.[11] Bulgaria's littoral forms 1/10 of the total Black Sea coastline, and includes two important gulfs, theGulf of Varna and theGulf of Burgas, harbouring the country's two major ports.[11]
The southern border is 752 km long, of them 259 km are withTurkey and 493 km are withGreece.[10][12] The Bulgaria–Turkey frontier runs from the mouth of the Rezovo River in the east through theStrandzha Mountains and theDervent Heights, crosses the riverTundzha at the village ofMatochina and ends at the riverMaritsa at the village ofKapitan Andreevo. There are three border crossings atMalko Tarnovo,Lesovo and Kapitan Andreevo.[12] The border with Greece runs from Kapitan Andreevo through several ridges of theRhodope Mountains, generally following the watershed of the riversArda andVacha on the Bulgarian side, runs through theSlavyanka Mountain, crosses the riverStruma at the village ofKulata and runs through the crest of theBelasitsa Mountain to theTumba Peak.[12] There are six border checkpoints atSvilengrad,Ivaylovgrad,Makaza,Zlatograd,Ilinden and Kulata.[12]
The western border is 506 km long, of them 165 km are withNorth Macedonia and 341 km are withSerbia.[10][13] The frontier with North Macedonia runs from the Tumba Peak in the south through the mountains ofOgrazhden,Maleshevo,Vlahina andOsogovo up to mount Kitka. There are three border crossings near the town ofPetrich and at the villages ofLogodazh andGyueshevo.[13] The border with Serbia runs from Kitka through the mountainous regionKraishte, including theRuy Mountain, crosses the valley of the riverNishava, runs through the main watershed of the westernBalkan Mountains and follows the riverTimok for 15 km until its confluence with the Danube.[13] There are five border checkpoints atDolno Uyno,Strezimirovtsi,Kalotina,Vrashka Chuka andBregovo.[13]
Therelief of Bulgaria is varied. In the relatively small territory of the country there are extensive lowlands, plains, hills, low and high mountains, many valleys and deep gorges.[14] The main characteristic of Bulgaria's topography is four alternating bands of high and low terrain that extend east to west across the country. From north to south, those bands, calledgeomorphological regions, are theDanubian Plain, theBalkan Mountains, the Transitional region and theRilo-Rhodope region. The easternmost sections near theBlack Sea are hilly, but they gradually gain height to the west until the westernmost part of the country is entirely high ground.[14]
Table, showing the distribution of the height zones in Bulgaria:[15]
| Height zones | Height (m) | Area (km2) | Area (%) |
|---|---|---|---|
| Lowlands | 0–200 | 34,858 | 31.42 |
| Hills | 200–600 | 45,516 | 41.00 |
| Low mountains | 600–1000 | 16,918 | 15.24 |
| Medium-high mountains | 1000–1600 | 10,904 | 9.82 |
| High mountains | 1600–2925 | 2,798 | 2.52 |
More than two-thirds of the country is plains, plateaus, or hilly land at an altitude less than 600 m. Plains (below 200 m) make up 31% of the land, plateaus and hills (200 to 600 m) 41%, low mountains (600 to 1,000 m) 10%, medium-high mountains (1,000 to 1,500 m) 10%, and high mountains (over 1,500 m) 3%.[15] The average altitude of Bulgaria is 470 m.
The contemporary relief of Bulgaria is a result of continuous geological evolution. The Bulgarian lands were often submerged by ancient seas and lakes, some land layers rose others sank.Volcanic eruptions were common both on land and in the water basins.[15] All three main groups of rocks,magmatic,sedimentary andmetamorphic, are found in the country.[14] The oldest rock formations in Bulgaria date from thePrecambrian period than 500 million years ago. During theArchean,Proterozoic andPaleozoic eras (4.0 billion to 252 million years ago) the magmatic rocks were formed. Throughout most of that period the only land areas were Rila, Pirin and the western Rhodope Mountains.[16] TheMesozoic era (252 million to 66 million years ago) saw the beginning of theAlpine orogeny that has formed the mountain ranges of theAlpide belt, including the Balkan Mountains andSredna Gora.[16] TheCenozoic era (since 66 million years ago) is characterized with active tectonic processes, the definitive formation of the Balkan Mountains, the formation ofgrabens andhorsts in Rila, Pirin and Kraishte region.[16]
Examples ofrock formations in Bulgaria:
Exogenous processes such asweathering,erosion andsedimentation have an important impact on modelling the land surface and creating rock formations.[17] The exogenous processes have formedstone rivers in Vitosha;screes in the Balkan Mountains, Rila and Pirin;earth pyramids inMelnik,Stob and Katina;landslides, mainly along the Danube banks and the northern Black Sea coast;fluvial terraces;aeolian forms, such asdunes;karst forms, including numerous caves,sinkholes,ponors, etc.[18]
TheDanubian Plain encompasses the Moesian plate and extends from the river Timok in the west to the Black Sea in the east and from the riverDanube in the north to the Balkan Mountains in the south, covering 31,520 km2, or almost 1/3 of Bulgaria's total area.[19] Its width varies from 25 to 30 km in the west to 120 km in the east. The highest point is Tarnov Dyal (502 m) on theShumen Plateau; the average altitude is 178 m.[20] As a result of the rock weathering processes the relief is uneven with fertilealluvial plains along the Danube (Vidinska, Chernopolska,Zlatia, Belenska, Pobrezhie, Aidemirska), and hilly terrain in the remaining area, including plateaus in the east. The altitude rises from west to east. The valleys of the riversVit andYantra divide the Danubian Plain into three parts – western, central and eastern.[20] The topography of the plain is characterized with hilly heights and plateaus. Most of the heights and all plateaus are situated in the eastern parts. There are 14basalt mounds betweenSvishtov and the village ofDragomirovo.[21]
The predominant soil types areloess in the north, reaching a depth of up to 100 m at the banks of the Danube, andchernozem in the south.[22] The climate istemperate. The flat relief and the openness of plain to the north facilitate arrival of moist air masses in spring, summer and autumn. In winter the Danubian Plain falls under the influence of the Eastern European anticyclone, which brings cold Arctic air masses.[22] The mean temperature in January is −1 °C and in July is 24 °C, making it the geomorphological region with the highest average annual amplitude in Bulgaria – 25 °C.[22]
TheBalkan Mountains range is a geological continuation of theCarpathian Mountains, forming part of theAlpine-Himalayan orogenic belt. This region is subdivided into two geomorphological units, the Pre-Balkan and the Balkan Mountains, also known in Bulgarian asСтара Планина – "Old Mountain". Their average altitude is 370 m and 735 m, respectively.[21] Its total area is 26,720 km2, of them the Pre-Balkan spans 15,730 km2 and the Balkan Mountains – almost 11,000 km2.[23] The mountain range stretches from the valley of the river Timok in the west toCape Emine at the Black Sea coast in the east, spanning a length of 555 km and width between 20 and 70 km.[24] The Balkan Mountains are divided into western, central and eastern part by theZlatitsa andVratnik Passes.[23] The range is highest in its central part, which includesBotev Peak at 2,376 m; the altitude drops slowly to the east until it reaches the sea. The relief is varied, with many mountain passes, gorges and landforms. The southern slopes are steeper than the northern.[21] For the most part the Balkan Range defines the most important watershed in Bulgaria with rivers draining north to the Danube or south to the riverMaritsa and theAegean Sea. Several rivers in the east drain directly into the Black Sea. In the west, the riverIskar forms a65-km long gorge that runs north through the mountains.[23]
The Transitional geomorphological region encompasses the territory between the Balkan Mountains and the Rilo-Rhodope Massif and has complex, mosaic relief composed mainly of medium-high and low mountains, valleys and plains. The altitude decreases from west to east.[25] This region includes theSub-Balkan valleys; the mountains and valleys of the Kraishte region, such asRuy Mountain,Miloslavska planina andMilevska Planina; the mountain rangesLyulin,Vitosha,Sredna Gora,Strandzha andSakar; theDervent Heights; as well as the fertileUpper Thracian Plain.[25] The highest point isCherni Vrah in Vitosha at 2,290 m.[25]
The Sub-Balkan valleys include eleven valleys, situated between the Balkan Mountains in the north and Vitosha and Sredna Gora in the south. With an area of 1,186 km2 and an average altitude of 550 m,Sofia Valley is the largest and contains the nation's capital,Sofia. TheRose Valley encompasses the valleys ofKarlovo andKazanlak and is renowned for itsrose-growing industry, which has been thriving there for centuries, producing 85% of the world'srose oil.[26] The Kazanlak Valley is also known as theValley of the Thracian Kings due to the extremely high concentration and variety of monuments of theThracian culture.
Srednogorie region stretches between the Sub-Balkan valleys in the north and the Rilo-Rhodope Massif in the south and from west to east includes the mountainsZavalska Planina,Viskyar, Lyulin, Vitosha,Plana and Sredna Gora. The largest of these, Sredna Gora, is 280 km and reaches a maximum width of 50 km.[26] Kraishte region covers the western parts of the Transitional geomorphological region and consists of two almost parallel mountain groups, Ruysko–Verilska and Konyavsko–Milevska, as well as numerous valleys.[27]
The Upper Thracian Plain encompasses the middle valley of the riverMaritsa and has a roughly triangular shape, situated between Sredna Gora in the north, the Rhodope Mountains in the south and Sakar Mountain in the east. The lowland is 180 km long and up to 50 km wide, spanning an area of 6,000 km2.[28] To the east are located the Burgas Plain,Svetiiliyski Heights,Manastirski Heights,Hisar Heights,Bakadzhitsite, Dervent Heights, and the low mountain ranges of Sakar and Strandzha.[29]
The Rilo-Rhodope geomorphological region covers the south-western regions of Bulgaria and includes theRhodope Mountains,Rila,Pirin,Osogovo,Vlahina,Maleshevo,Ograzhden,Slavyanka andBelasitsa, as well as the valleys of the riversStruma andMesta.[25] The Rhodopes are the most extensive mountain range in Bulgaria, spanning an area of 14,730 km2 with an average altitude of 785 m, characterized with gentle and densely forested slopes. Their length from west to east is 249 km and reach width of 100 km.[30] The altitude decreases from west to east.[25]
To the west are located Rila and Pirin, Bulgaria's two highest mountains. Rila includesMount Musala, whose 2,925 m peak is the highest in theBalkan Peninsula, while Pirin's highest peakVihren at 2,915 m is the third-highest in the Balkans. Both Rila and Pirin have rocky peaks, stony slopes, extensiveAlpine zone and hundredsglacial lakes.[31] Further west is the Osogovo–Belasitsa mountain group along the border with North Macedonia, whose highest peak isRuen in Osogovo at 2,251 m.[32]
TheBulgarian Black Sea Coast has a total length of 378 km fromDurankulak in the north to the mouth of the riverRezovska in the south.[33] The northernmost section between the Bulgarian-Romanian border toShabla has extensive sandy beaches and several coastal lakes, then the elevation rises as the coast reaches CapeKaliakra, with 70 m high vertical cliffs. NearBalchik andKavarna the limestone rocky coast is cut by wooded valleys. The landscape around the coast resorts ofAlbena andGolden Sands is hilly, with a clearly expressed land slides. Dense forests at the mouth of the riverBatova mark the beginning of Frangensko plateau. South ofVarna the coastline is densely wooded, especially at the alluvial longose groves of theKamchia Biosphere Reserve.Cape Emine marks the end of the Balkan Mountain and divides the Bulgarian Black Sea coast in northern and southern parts. The southern section has wide and long beaches, with a number of small bays and headlands.[33] All Bulgarian Black Sea islands are situated in the southern coast:St. Anastasia,St. Cyricus,St. Ivan,St. Peter andSt. Thomas. Sandy beaches occupy 34% of the Bulgarian coastline.[34] The two most important gulf are theGulf of Varna in the north and theGulf of Burgas in the south, which is the largest in the Bulgarian Black Sea coast.[33]
Considering its relatively small area, Bulgaria has variable and complex climate. The country occupies the southernmost part of thecontinental climatic zone, with small areas in the south falling within theMediterranean climatic zone.[35] The continental zone is predominant, because continental air masses flow easily into the unobstructedDanubian Plain. The continental influence, stronger during the winter, produces abundant snowfall; the Mediterranean influence increases during the second half of summer and produces hot and dry weather. Bulgaria is subdivided into five climatic zones: continental zone (Danubian Plain, Pre-Balkan and the higher valleys of the Transitional geomorphological region); transitional zone (Upper Thracian Plain, most of the Struma and Mesta valleys, the lower Sub-Balkan valleys); continental-Mediterranean zone (the southernmost areas of the Struma and Mesta valleys, the eastern Rhodope Mountains, Sakar and Strandzha); Black Sea zone along the coastline with an average length of 30–40 km inland; and alpine zone in the mountains above 1000 m altitude (central Balkan Mountains, Rila, Pirin, Vitosha, western Rhodope Mountains, etc.).[36]
Despite the large distance, the most important climate-forming factor is the Atlantic Ocean through the atmospheric circulation of theIcelandic cyclone and theAzores anticyclone, which bring cool and rainy weather in summer and relatively mild weather with abundant snowfall in winter.[38][39] The influence of theMediterranean Sea is strongest in the southern parts of Bulgaria, mainly through the Mediterranean cyclones. Due to its small area, the influence of theBlack Sea only affects a 30–40 km long strip along the coastline, mainly in summer, when the dailybreeze circulation is most pronounced.[39][40]
Another important factor is the relief. The Bulgarian mountains and valleys act as barriers or channels for air masses, causing sharp contrasts in weather over relatively short distances. The Balkan Mountains form a barrier which effectively stops the cool air masses coming from the north and the warm masses from the south.[40] The barrier effect of the Balkan Mountains is felt throughout the country: on the average, northern Bulgaria is about one degree cooler and receives about 192 mm more rain than lowlands of southern Bulgaria. The Rilo-Rhodope Massif bars the warm Mediterranean air masses and limits the Mediterranean influence to the southern valleys of the rivers Struma, Mesta, Maritsa and Tundzha, despite the close proximity of theAegean Sea.[39][40]
The mean annual temperature in Bulgaria is 10.6 °C and varies from 2.2 °C at the nation's highest peak Musala to 14.7 °C (1991-2021 Climate data) at the town ofSandanski in the southern Struma valley.[41] The average temperature in the Danubian Plain is 11.4 °C, in the Upper Thracian Plain 13.9 °C, in the lower mountains 8.1 °C and in the higher mountains 2.4 °C.[41] The highest absolute temperature was measured at the town ofSadovo in 1916 45.2 °C; the lowest absolute temperature was measured at the town ofTran in 1947 –38.3 °C.[39][41] The highest temperature in the lowlands and the hilly regions is in July, while in the higher mountains the warmest month is August. The lowest temperature is measured in January (Dragoman - average monthly temperature: -2, Ahtopol: + 4,2) and February, respectively.[41] Many valleys experience regulartemperature inversions and fogs in winter. The country's lowest absolute temperature was measured during an inversion in the Tran valley : −38.3 °C .[40]
The averageprecipitation in Bulgaria is about 670 mm.[42] It is uneven in terms of seasons and territory. In northern Bulgaria the highest precipitation is in May–June, while in southern Bulgaria it is in winter. The average amount of precipitation also varies in term of altitude – from 450 to 850 mm in the plains to 850–1200 mm.[43] The lowest mean precipitation is in the eastern part ofDobrudzha and the Burgas Plain (450 mm) and in the area betweenPlovdiv andPazardzhik (500 mm); the highest rainfall falls in the mountains – thePetrohan Pass in the western Balkan Mountains andZlatograd in the Rhodope Mountains.[43] The highest annual rainfall was measured in 1957 in the upper valley of the riverOgosta in the western Balkan Mountains (2293 mm); the highest daily rainfall was recorded atSaints Constantine and Helena resort (342 mm) nearVarna in 1951.[43] The total annual amount of the rainfall is 74 billion km3; of them 70% evaporate, 20% flow into the rivers and 10% soak into the soil.[43] Most of the country is affected by droughts in June and August. The snow cover lasts from 20 to 30 days in the lowlands to 9 months in the highest mountains.[43]
| Climate data for Bulgaria (records from all meteo stations) | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °C (°F) | 24.8 (76.6) | 26.7 (80.1) | 35.7 (96.3) | 37.1 (98.8) | 38.8 (101.8) | 42.0 (107.6) | 45.2 (113.4) | 44.5 (112.1) | 41.9 (107.4) | 39.2 (102.6) | 32.4 (90.3) | 28.6 (83.5) | 45.2 (113.4) |
| Record low °C (°F) | −38.3 (−36.9) | −35 (−31) | −30.2 (−22.4) | −20.6 (−5.1) | −15.6 (3.9) | −12 (10) | −8 (18) | −9.8 (14.4) | −14 (7) | −17.8 (0.0) | −27.4 (−17.3) | −33.5 (−28.3) | −38.3 (−36.9) |
| Source: Stringmeteo.com, February record high :http://eea.government.bg/bg/soer/2016/climate/climate0November record high :https://m.dir.bg/weather/novini/s-32-4-c-veliko-tarnovo-schupi-95-godishen-natsionalen-rekord | |||||||||||||
| Climate data for Sofia (NIMH−BAS) 1991–2020 normals, extremes 1893–present | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °C (°F) | 19 (66) | 23 (73) | 27.5 (81.5) | 31 (88) | 34.1 (93.4) | 38 (100) | 41 (106) | 39.4 (102.9) | 36.1 (97.0) | 33.9 (93.0) | 25.8 (78.4) | 23 (73) | 41 (106) |
| Mean daily maximum °C (°F) | 3.6 (38.5) | 6.5 (43.7) | 11.5 (52.7) | 16.7 (62.1) | 21.4 (70.5) | 25.3 (77.5) | 27.9 (82.2) | 28.4 (83.1) | 23.3 (73.9) | 17.6 (63.7) | 10.7 (51.3) | 4.6 (40.3) | 16.5 (61.6) |
| Daily mean °C (°F) | −0.5 (31.1) | 1.6 (34.9) | 5.8 (42.4) | 10.8 (51.4) | 15.5 (59.9) | 19.3 (66.7) | 21.5 (70.7) | 21.5 (70.7) | 16.8 (62.2) | 11.4 (52.5) | 5.9 (42.6) | 0.8 (33.4) | 10.9 (51.5) |
| Mean daily minimum °C (°F) | −3.8 (25.2) | −2.3 (27.9) | 1.1 (34.0) | 5.4 (41.7) | 9.9 (49.8) | 13.4 (56.1) | 15.3 (59.5) | 15.3 (59.5) | 11.1 (52.0) | 6.7 (44.1) | 2.2 (36.0) | −2.3 (27.9) | 6.0 (42.8) |
| Record low °C (°F) | −31.2 (−24.2) | −25 (−13) | −19 (−2) | −6 (21) | −2.2 (28.0) | 1.4 (34.5) | 2 (36) | 3.5 (38.3) | −2 (28) | −6 (21) | −15.3 (4.5) | −21.1 (−6.0) | −31.2 (−24.2) |
| Averageprecipitation mm (inches) | 35.9 (1.41) | 35.5 (1.40) | 45.3 (1.78) | 52.3 (2.06) | 73.1 (2.88) | 81.6 (3.21) | 64.7 (2.55) | 53.1 (2.09) | 52.3 (2.06) | 53.9 (2.12) | 38.1 (1.50) | 39.9 (1.57) | 625.7 (24.63) |
| Average snowfall cm (inches) | 24.5 (9.6) | 20.6 (8.1) | 14.8 (5.8) | 3.1 (1.2) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 1.5 (0.6) | 10.4 (4.1) | 20.7 (8.1) | 95.6 (37.5) |
| Average precipitation days | 10.2 | 9.5 | 10.9 | 10.7 | 13.8 | 10.9 | 7.7 | 7.3 | 8.7 | 9.6 | 7.1 | 10.3 | 116.7 |
| Average snowy days | 7.5 | 6.5 | 5.2 | 1.3 | 0 | 0 | 0 | 0 | 0 | 0.7 | 2.7 | 6.4 | 30.3 |
| Mean monthlysunshine hours | 87.9 | 117.2 | 169 | 195.1 | 236 | 268.1 | 311.9 | 307.3 | 225.1 | 166.8 | 107.7 | 69.1 | 2,261.2 |
| Averageultraviolet index | 1 | 2 | 4 | 5 | 7 | 9 | 9 | 8 | 6 | 4 | 2 | 1 | 5 |
| Source: Stringmeteo.com,[44][45][46][47][48] Climatebase.ru (precipitation days and extremes),[49][50]NOAA,[51] freemeteo.bg[52][53][54][55] and Weather Atlas[56] | |||||||||||||
| Climate data for Ahtopol (NIMH−BAS) 1991–2020 normals, | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Daily mean °C (°F) | 4.2 (39.6) | 4.9 (40.8) | 7.4 (45.3) | 11.1 (52.0) | 15.8 (60.4) | 20.4 (68.7) | 23.2 (73.8) | 23.3 (73.9) | 19.5 (67.1) | 15 (59) | 10.1 (50.2) | 6.1 (43.0) | 13.4 (56.1) |
| Source: Stringmeteo.com,[44][45][57][58][59] Climatebase.ru (precipitation days and extremes),[49][50]NOAA,[51] freemeteo.bg[52][53][54][55] and Weather Atlas[56] | |||||||||||||
Bulgaria has a dense network of about 540 rivers, but with the notable exception of theDanube, most have short length and low water-level. The density is highest in the mountain areas and lowest in Dobrudzha, the Danubian Plain and the Upper Thracian Plain.[5] There are two catchment basins: theBlack Sea (57% of the territory and 42% of the rivers) and theAegean Sea (43% of the territory and 58% of the rivers) basins.[5][60]
TheBalkan Mountains divide Bulgaria into two nearly equaldrainage systems. The larger system drains northward to the Black Sea, mainly by way of the Danube. This system includes the entire Danubian Plain and a stretch of land running 48–80 km inland from the coastline in the south. The Danube gets slightly more than 4% of its total volume from its Bulgarian tributaries. As it flows along the northern border, the Danube averages 1.6 to 2.4 km in width. The river's highest water levels usually occur during the May floods; it is frozen over an average of 40 days per year. The longest river located entirely in Bulgarian territory, theIskar, with a length of 368 km and a catchment area of 8,640 km2, is the only Bulgarian Danubian tributary that does not rise in the Balkan Mountains. Instead, the Iskar has its origin in the Rila Mountains. It passes through Sofia's eastern suburbs and crosses the Balkan Mountains through a spectacular 65 km–long gorge.[5] Other important tributaries of the Danube include the riversLom,Ogosta,Vit,Osam andYantra.[5][60] The longest river flowing directly to the Black Sea is theKamchiya (254 km), while other rivers include theBatova,Provadiya,Aheloy,Ropotamo,Veleka andRezovo.[61]
The Aegean Sea catchment basin drains theThracian Plain and most of the higher lands to the south and southwest. Several major rivers flow directly to the Aegean Sea. Most of these streams fall swiftly from the mountains and have cut deep, scenic gorges. The 480 km–longMaritsa (of them 321 km in Bulgaria) and its tributaries drain all of the westernThracian Plain, all ofSredna Gora, the southern slopes of the Balkan Mountains, and the northern slopes of the eastern Rhodopes. After it leaves Bulgaria, the Maritsa forms most of the Greco-Turkish border.[61] Maritsa's major tributaries include theTundzha,Arda,Topolnitsa,Vacha,Stryama, etc. The other Bulgarian rivers flowing directly to the Aegean are theStruma and theMesta.[60][61]
Bulgaria has around 400 natural lakes with a total area of 95 km2 and volume of 278 million km3.[62] Thelimans and lagoons along the Black Sea coast include from north to southLake Durankulak,Lake Shabla,Lake Varna,Lake Beloslav,Lake Pomorie,Lake Atanasovsko,Lake Burgas andLake Mandrensko. Of them, Lake Burgas is the most extensive with 27,6 km2 and Lake Varna has the largest volume with 165,5 million m3.[60][62] The lakes along the Danube were dried to clear land for agriculture with the notable exception of theUNESCOWorld Heritage SiteLake Srebarna.[62] There are 170glacial lakes in Rila and 164 in Pirin. They are an important tourist asset. The most renown lakes include theSeven Rila Lakes,Popovo Lake,Banderishki Lakes,Vasilashki Lakes,Vlahini Lakes, etc.[62]Swamps andmarshes includeAlepu,Arkutino,Aldomirovtsi Marsh,Dragoman Marsh, etc.[63] There are around 2,200 reservoirs with a total volume of c. 7 billion km3.[60] The largest ones areIskar Reservoir,Ogosta Reservoir,Dospat Reservoir,Batak Reservoir,Kardzhali Reservoir,Ivaylovgrad Reservoir,Studen Kladenets,Koprinka Reservoir,Ticha Reservoir, etc.[63]
Bulgaria is rich inmineral waters, with 225 mineral springs and a total discharge of 5000 L/s, mainly in the south-western and central parts of the country along the faults between the mountains.[64] Most of them, 148, are situated in southern Bulgaria, while the other 77 are in the northern part of the country. The springs in the north tend to be with cool water, while those to the south are mainly warm and hot. The hottest spring in Bulgaria and the Balkans is situated inSapareva Banya and reaches 101.4 °C.[64] The Bulgarian word for spa,баня, transliterated asbanya, appears in some of the names of more than 50spa towns and resorts. They are located in several zones:Balkan Mountains zone (Varshets,Shipkovo,Voneshta Voda),Srednogorie zone (Sofia,Ovcha kupel,Bankya,Pancharevo,Strelcha,Hisarya,Banya,Pavel Banya),Maritsa zone (Kostenets (town),Kostenets (village),Dolna Banya,Momin Prohod),Rilo-Rhodope zone (Devin,Velingrad,Banite,Beden,Mihalkovo, Sapareva Banya),Struma zone (Kyustendil,Sandanski,Ognyanovo,Marikostinovo,Dobrinishte).[65]
Thesoil cover of Bulgaria is diverse. The soil resources of the country are adequately researched and include 17soil types and 28 sub-types.[66] Of them, six types form 88.7% of the soil cover:cinnamon soils (22.0%);chernozem (20.4%); grey forest soils (17.0%); brown forest soils (14.8%);alluvial soils (9.0%) and smolnitsi (5.4%).[66]
There are three soil zones. TheNorthern forest-steppe zone covers the Danubian Plain and the Pre-Balkan up to 600–700 m altitude. The Danubian Plain is characterised by the fertile black earth chernozem, that accounts for 54% of the zone's area, while the Pre-Balkan is dominated by grey forest soils (39%), which have good physical characteristics but are low in organic matter and phosphorus.[67][68] TheSouthern xerothermal zone encompasses Southern Bulgaria up to 700–800 m altitude and includes several specific soil types due to the more diverse topography and climate. The most common soil types are the cinnamon forest soils with acidic (cinnamonic) traces, smolnitsi and yellow-podzolic soils.[67][68] TheMountain zone covers the mountainous regions above 700–800 m altitude and has a zonal soil cover. The brown forest soils are distributed at altitudes of 1000–2000 m, the dark mountain forest soils can be found at 1700–2200 m altitude and the mountain meadow soils – above 1700 m. These soils are typically shallow and prone to erosion and are usually acid to strongly acid.[67][68]
| Type | 1000ha |
|---|---|
| cinnamon | 2,430 |
| chernozem | 2,240 |
| grey forest | 1,960 |
| brown forest | 1,640 |
| meadow, alluvial anddiluvial | 995 |
| smolnitsi | 595 |
| yellow-podzol | 0.026 |
| salty | 0.025 |
| mountain meadow | 173 |
| other | 1,016 |
There are approximately 60 types of minerals that are extracted commercially in Bulgaria.[70] The mineral resources are divided into three groups:fossil fuels, metals andindustrial minerals.
The fossil fuels include coal, petroleum and natural gas. Bulgaria possesses significant reserves of coal estimated at 4,8 billion tons.[71] More than 92% of them, or 4,5 billion tons,[71] islignite, which is the lowest rank of coal due to its relatively low heat content but is widely used for electricity generation. With reserves of 2,856 billion tons Maritsa Iztok, situated in the Upper Thracian Plain, is by far the largest coal basin in the country which powersMaritsa Iztok Complex, the largest energy complex in South-Eastern Europe.[72] Other lignite basins include Sofia valley (reserves of 870 million tons),Elhovo (656 million tons),Lom (277 million tons), Maritsa Zapad (170 million tons).[72] The reserves ofsub-bituminous coal are 300 million tons, situated mainly nearBobov Dol,Pernik andBurgas.[73] The recoverable reserves ofbituminous coal andanthracite are insignificant – only 10 and 2,5 million tons respectively. However, there is a huge basin of bituminous coal inSouthern Dobruja with estimated reserves of over 1 billion tons but its large depth (1370–1950 m) is an obstacle for its commercial exploitation.[74]
The Bulgarianexclusive economic zone has a total size of 110,879 km2 (42,811 sq mi) in the Black Sea. Petroleum and natural gas are found in northern Bulgaria and its EEZ in the Black Sea. Crude oil is extracted inDolni Dabnik andGigen in Pleven Province and inTyulenovo, Dobrich Province. The proven reserves are 20 million tons but there are prospects for new discovering in the EEZ.[75] Gas fields have been discovered off capeKaliakra (reserves of 3 billion m3),Deventsi (6 billion m3), betweenLovech andEtropole (est. 22 billion m3),[76] as well as nearDevetaki andButan.[75] It is estimated that the 14,220 m2Khan Asparukh Block in the northern section of the Bulgarian EEZ has natural gas reserves of 100 billion m3.[76]
Bulgaria has significant reserves of metal ores, especially copper, zinc and lead, situated mainly in the southern half of the country. The two largest iron ore mines are located inKremikovtsi near Sofia andKrumovo, Yambol Province with total reserves of 430 million tons.[77]Manganese ore is extracted nearObrochishte in Dobrich Province (reserves of 85 million tons), as well as in the provinces of Sofia and Varna. The reserves ofchromium are small and are scattered in the Rhodope Mountains.[78] Bulgaria possesses important reserves of lead andzinc, of them 60% are situated in the southern reaches of the Rhodope Mountains along the border with Greece atMadan,Zlatograd,Madzharovo,Rudozem,Laki, etc. Other mines are located nearUstrem andGyueshevo.[78] The reserves of copper ore are also significant, situated mainly atAsarel Medet nearPanagyurishte,Elatsite mine near Etropole (650 million tons),Elshitsa, Medni Rid nearBurgas, etc.[78] There is gold nearTran,Chelopech and Madzharovo, as well as small quantities ofplatinum, silver,molybdenum,nickel andtungsten.[79]
Bulgaria is rich in industrial minerals, with 70 types being mined. There are important reserves ofrock salt near the town ofProvadia (4,4 billion tons).Solnitsata, an ancient town located nearby is believed by Bulgarian archaeologists to be the oldest in Europe and was the site of a salt production facility approximately six millennia ago.[79][80] The reserves ofkaolinite are estimated at 70 million tons, situated mainly in north-eastern Bulgaria –Kaolinovo,Todor Ikonomovo,Senovo andVetovo.[81]Marble is extracted in the mountainous regions – Pirin, Rhodopes, Strandzha, the western Balkan Mountains.[82] There are important quantities oflimestone,gypsum,baryte,perlite,feldspar,granite, etc.[83]
The interaction of climatic, hydrological, geological and topographical conditions make Bulgaria one of the most biologically diverse countries of Europe.[84]Phytogeographically, Bulgaria straddles theIllyrian andEuxinian provinces of theCircumboreal Region within theBoreal kingdom. The country falls within six terrestrialecoregions of thePalearctic realm:Balkan mixed forests,Rodope montane mixed forests,Euxine-Colchic deciduous forests,Aegean and Western Turkey sclerophyllous and mixed forests,East European forest steppe andPontic–Caspian steppe.[8] Around 35% of Bulgaria's land area consists of forests,[85] which include some of the oldest individual trees in the world, such asBaikushev's pine and theGranit oak.[86] Bulgaria's flora contains between 3,800[87] and 4,200[88]vascular plant species of which 170 areendemic and 150 are considered endangered. There more than 6,500 species ofnon-vascular plants andfungi.[84]
Bulgaria's vertebrate fauna is among the most diverse in Europe.Forest cover is around 36% of the total land area, equivalent to 3,893,000 hectares (ha) of 2020, up from 3,327,000 ha in 1990. In 2020, naturally regenerating forest covered 3,116,000 ha and planted forest covered 777,000 ha. Of the naturally regenerating forest 18% was reported to beprimary forest (consisting of native tree species with no clearly visible indications of human activity) and around 18% of the forest area was found within protected areas. In 2015, 88% of the forest area was reported to be underpublic ownership and 12%private ownership.[89][90]
There are three zoogeographical regions; the Eurosiberian region, encompassing the Danubian Plain and the mountainous regions of the country; theIrano-Turanian Region encompassing Southern Dobrudzha; and the Mediterranean region that includes the Upper Thracian Plain, the lower Struma valley and the Black Sea coast.[91] Bulgaria is inhabited by around 100mammal species, includingbrown bears,grey wolves,wild boars,golden jackals,red foxes,wildcats,red deer,roe deer,European fallow deer,European hares,southern white-breasted hedgehogs,badgers,marbled polecats,European polecats,European pine martens, four species ofoceanic dolphins, andMediterranean monk seals. Protection, reintroductions and repopulations like those of theEuropean bison, theEurasian beaver, and theEurasian lynx[92] are intended and reported.
Theavian fauna is represented by 434 species ofbirds, which is the second highest number in Europe.[93] Almost all species of thetrue owls live in the country, alsowhite stork,common crane, anddemoiselle crane. Important conservation species are theeastern imperial eagle, thecinereous,griffon,Egyptian and thebearded vultures, thegreat white pelican, and theDalmatian pelican.
There are38 reptile and the20 amphibian species found in Bulgaria. There are fourturtle and twotortoise species of four families –Cheloniidae,Emydidae,Geoemydidae andTestudinidae; fourteenlizard species of four families –Anguidae,Gekkonidae,Lacertidae andScincidae; and eighteensnake species of four families –Boidae,Colubridae,Typhlopidae andViperidae.
Theichthyofauna (fish) of the country has not been fully researched, but there is a rich variety ofsturgeons,Black Sea shark,longnose spurdog,thornback ray,common stingray,northern pike,European eel, etc. As of 2000 there were 207 fish species.[94]
There are an estimated 27,000 species of insects and other invertebrates.[84]
Concern about biodiversity conservation remains strong within the country. In 1998 theGovernment of Bulgaria approved the National Biological Diversity Conservation Strategy, which was inspired by the Pan European Strategy for Biological and Landscape Diversity.[95] Bulgaria has some of the largestNatura 2000 areas in theEuropean Union covering 33.8% of its territory.[96] The national policy for governing and management of the protected areas is implemented by theMinistry of Environment and Water. Bulgaria's biodiversityis conserved in three national parks, 11 nature parks[97] and 55nature reserves.[98][99] Of them,Pirin National Park,Srebarna Nature Reserve andnine forest reserves within theCentral Balkan National Park are included in theUNESCOWorld Heritage List.[100][101] Spanning a territory of 1,161 square kilometresStrandzha Nature Park is the largest protected area in the country.[102] Established in 1936Vitosha Nature Park is the oldest in Bulgaria and in the Balkan Peninsula.[103]
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