Danube Delta & Dobrogea
The Dobrogea Region
“This largely dry region nestles between the River Danube, as it flows from south to north before forming the delta, and the lagoons and Black Sea to the east. The landscape is typically rolling steppe and agricultural country, dotted with woodlands and brackish and freshwater lakes. Many of the birds that inhabit the delta can also be seen here and in addition there are some, like Red-breasted Goose, Levant Sparrowhawk, Collared Pratincole, Pied Wheatear, Calandra Lark and Spanish Sparrow that are easier to locate here than in the delta.”
(Gerard Gorman, ALULA 4/2000 volume 6)
The map above shows the protected areas in Dobrogea region. As you can see more than 50% of the area is under protection, this makes the largest compact protected area in Europe. The migration pass, known as Via Pontica is the most important in Europe.
The birds are concentrated by the Carpathians at West and by the Black Sea (E) forced to follow the sea shore and cross the steppes of Dobrogea. Masses of birds are crossing this magnificent area every year.
The flora of Dobrogea region is very rich as it concentrates 1911 species on 16000 km square being comparable to the plant diversity of the Mediterranean islands Corsica and Crete. This represents more than 50% of Romanian flora.
This region represents a complex synthesis of the plant biogeographic areas as it is situated at the southern limit of the Central European and some Crimean species, at the northern limit of the Mediteranean-Balkanic – Pontic species and at the western limit of some Asiatic ones.
The complex structure of the flora and its specificity, beside the Euro-Asiatic species (25%), is conferred by the high proportion of southern – Balkanic, Pontic – Mediterranean, Sub-mediterranean species (25%) and by the Continental, steppe species (17%).
The European and Central European (12%) and Circumboreal (4%) species are less frequent and occur on higher altitudes. All these features confer to Dobrogea the character of synthesis of southeast European flora and not only. A plant hunting trip to Dobrogea is more or less equivalent to a much larger visit to central Europe, northern Greece, Bulgaria, Turkey, the Crimean Mountains and the steppes of Ukraine and Central Asia.
The Danube Delta
“Europe’s last nature paradise” says Jan Hopman in his article from Grasduinen one of the most important nature magazine in Holland (April 2000).
“Indeed, the Danube Delta’s reedbeds constitute the largest expanse in the world covering 2,700 square km” … “If all this were not enough there is also, in addition to the delta proper around 880 square km of lagoons, saltmarsh, sandy and shingle beaches and other coastal habitats to the immediate south” … “No other European wetland west of the Volga can compete with the Danube Delta in size, diversity and overall magnificence.” says Gerard Gorman in an article from ALULA one of the most important ornithological magazine in Finland.
Size and position
With its 4,152 sq. km is the second largest Delta in Europe after Volga Delta. Situated in the eastern part of Europe and lies at the intersection of 45 oN (parallel of latitude) with 29 oE (longitude).
The total area of the Danube Delta Biosphere Reserve is about 580,000ha, more than half of which embraces what is commonly called the “Danube Delta”. The remaining area is shared between the upstream Danube flood plain and the lagoon complex – Razelm Sinoe.
Short historical view
The first to notice the deltoid shape of this system was probably, Herodotus studying the Nile Delta nearly 2,500 years ago. His “Histories” provide the first information of the Danube (Istros) and its delta. Since ancient times the Danube Delta has been an object of interest to European people.
Hypsometry
The Danube Delta is a very low flat plain, lying 0.5m above Mean Black Sea Level with a general gradient of 0.006m/km. The highest point o the delta is given by the sand dunes in Letea (+12.4m) and the maximum depth is on Chilia arm (-39 m).
Hydrographic network
According to the most recent measurements the total length of the natural streams is 1,743 km and that of the channels is about 1,753km.
Lakes
There are 479 lakes in the Delta. In the western part of the delta where the siltation is more intense, the lakes are more numerous, small and shallow (<1.0 m depth) while in the lower-lying eastern part, their number is reduced but the individual size is considerably larger. Their average depth is 1-2m, sometimes up to 3 m.
The Razim-Sinoe lagoon complex is the largest lacustrine area of Romania covering 101,500ha. It was formed by closing off the old marine gulf of Halmyris and now is separated by the Black Sea only by a narrow beach ridge. The depth of these lakes ranges between 1.0m and 3.5m.
Hydrology
During the period 1921-1990 the average annual water discharge was 6,570 cubic meters/sec at the delta entrance; the extreme value of 17,700 cubic meters/sec was recorded in 1958. The average annual suspended sediment discharge was 29.2 million tons in the period 1981-1990. In the delta the amount of incoming sediment/year is about 1,5 million tons, a large part of which is deposited in secondary streams, canals and lakes.
Climate
The Danube Delta has a continental-temperate climate with some pontic (marine) influence. The average number of hour sunshine is about 2,500 hours/year.
Average annual air temperature is 11 degrees Celsius with a minimum average in winter of -1.5 C (January) and max average in summer 22.7 C (July).
Absolute minimum air temperature – 27.2 C (18.01.1963)
Absolute maximum air temperature + 39.7 C (02.08.1945)
Precipitation is influenced by the north Dobrogean tableland and by the Black Sea. The average precipitation is 438.4 mm in Tulcea and 330.5 mm at Sulina. The snow starts to fall in the second week of December until the middle of March.
The air humidity of about 80%, is the highest in Romania, and increases towards the east: 80% at Tulcea and 86% at Sulina. In wintertime air humidity in Sulina may reach up to 90%.
The number of cloudless days is 66 in Tulcea and 80 at Sfantu Gheorghe.
The potential evapotranspiration is > 700 mm/year. The Danube Delta has one of the highest atmospheric moisture deficits in Romania (- 300 – 400 mm).
Aeolian condition – Winds blow 80% of the year and with almost the same frequency from all directions. However, the prevailing direction is from the northwest, followed by the north wind. The highest speed winds – 8.4 m/s -were recorded near the sea.
Human settlements
The first signs of human settlements discovered in the delta date from before the Middle Ages, and even go as far back as the Neolithic Age. The ruins of the ancient Greek cities of Histria and Argamum bear witness this fact and lie on the western side of the present day Razim Sinoe lagoon complex, they were built in the 6th- 5th centuries BC. Constantine VII the Porphyrogenitus (950) mentions the present town of Sulina by the name of Sollina. During the Turkish Empire, which started at the beginning of 15th century, some new settlements where established – Caraorman (1819). The most recent settlement in the Danube Delta is Maliuc in 1953.
Population
In the 20th century the population of the Danube Delta fluctuated between 15,000 and 21,000 inhabitants, being strongly influenced by the two world wars and the development of the town of Tulcea. The population of 15,590 recorded in 1992 was the lowest population. (Ecosystems of the Romanian Danube Delta Biosphere Reserve – Danube Delta Institute).
