Skip to comments.Human Impact Felt On Black Sea Long Before Industrial Era
Posted on 09/08/2012 6:13:53 PM PDT by SunkenCiv
In the delta's early stages of development, the river deposited its sediment within a protected bay. As the delta expanded onto the Black Sea shelf in the late Holocene and was exposed to greater waves and currents, rather than seeing the decline in sediment storage that he expected, Giosan found the opposite. The delta continued to grow. In fact, it has tripled its storage rate.
If an increase in river runoff was responsible for the unusual rapid build up of sediment in the delta, says Giosan, the question is, "Was this extraordinary event in the Danube delta felt in the entire Black Sea basin? And if so, what caused it?"
...The largest and longest river in the European Union, the Danube is the source of over 60 percent of the freshwater running into the Black Sea, and therefore is a dominant factor in the biogeochemistry of this basin. Because the Black Sea is nearly enclosed, changes in its hinterland provoked by climate or people should be readily reflected there...
Salinity began to rise in the Black Sea about 9000 years ago, when the ocean invaded the previously freshwater lake through the Straits of Bosporus, and continued to increase until approximately 3000 years ago, when the levels approached normal ocean values.
"But the trend since then is counter-intuitive," says Giosan. "The entire basin freshened, especially in the last 1,500 years." The likely explanation points to a increase in the river input combined with a reduced evaporation as the climate cooled at the time, he adds...
(Excerpt) Read more at sciencedaily.com ...
A map of the Black Sea's drainage basin. The Danube's watershed is delimited by a continuous white line, its course is highlighted in blue, and the Danube delta is shown in green. The Danube drains most of the Central and Eastern Europe to dominate the freshwater and sediment budget of the Black Sea. A sediment core shown by a white circle was used to reconstruct the salinity and ecosystem composition in the Black Sea over the last 7000 years. (Credit: Figure courtesy Liviu Giosan, Woods Hole Oceanographic Institution; Stefan Constantinescu, University of Bucharest)
thanks for posting this !
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In the valleys of the east cental Black Forest of Germany arise two small rivers: The Breg and the Brigach. They come together to form the Donau (German for Danube) on the one-time estate of the Fürstenburg Counts called Donaueschingen.
This confluence, the official source of the Danube, is in view of a bridge over the river carrying Federal Highway (Bundesstrasse) 27 southward out of Stuttgart, heading toward the Swiss border.
The source of the longer of these two small rivers, the Breg, begins as a little brooklet emerging from under a headstone at the upper, western, end of a picturesque valley that features an inn and restaurant, and a small chapel nearby. You reach this point on a narrow road that clings to the north side of the valley; a fifty metre path leads down to the source itself, where you can dip your hands into, and sample, the furthest source of one of the two great storied rivers of Europe.
Interestingly, the other river, the Rhein, is not far away, despite the fact that it empties eventually into the North Sea. So the continential divide between the Black Sea (& Mediterranean) and the North Sea, snakes its way across southern Germany, quite close to both rivers.
During the Ice Age, the Rhine in Germany and the Thames in England were the same river. They were connected over what is now the English Channel.
That’s interesting, too. Where did the combined river empty? Did the Thames-to-be flow the opposite to its present-day course and empty out into the Irish Sea somewhere in Wales(-to-be)?
Awesome. You ought to write travel books. Do you have any photos to post?
My own pics were on a roll I lost before I could get it developed (along with shots of the site of the final German WWII nuclear reactor experiment in Haigerloch).
However, you can see pics in Wikipedia under "Breg River." Try the German Wiki for a little more data than the English Wiki entry.
I would guess they both emptied into and joined in the low spot which is now filled with the water known as the English Channel.