The building of dams is a polarising subject, yet there is little doubt that once built, many of them are among the most stunning of human-made structures.
When it comes to ranking the biggest dams, it depends on whether we are looking for the tallest, the longest, or perhaps the one comprising the most material.
According to the United States Bureau of Reclamation, a federal government agency that oversees water resource management, the world’s largest dam by volume of construction material is the Syncrude tailings dam, in Canada, at 540 million cubic metres.
By comparison, the bureau notes, Hoover Dam, a visually stunning structure on the Colorado River on the border between the states of Nevada and Arizona, contains a mere 2.6 million cubic metres of concrete.
But what about a dam that was meticulously planned but never built, a dam so big that at the time it was proposed, some experts doubted there was enough concrete in the world to construct it?
Herman Sorgel, a German architect from Bavaria, was born on 2 April 1885. Beginning in 1927, he stood among the ruins – both physical and political – left behind after the First World War and envisioned a project that would bring prosperity and peace to Europe. Indeed, he felt, it would change the face of the world.
Sorgel called his project Alantropa, and its linchpin was the construction of a dam at the Strait of Gibraltar that would separate the Atlantic Ocean from the Mediterranean Sea, along with dams from Italy to Sicily and on to Africa, north of Tunisia, dividing the sea into two basins. There would also be a dam across the Strait of the Dardanelles, holding back the Black Sea.
From the US, a 2011 master’s thesis by University of Tennessee student Ryan Linger says Sorgel planned the Gibraltar dam to be “a slightly asymmetrical arch of around 35 kilometres between two offset points near the Bay of Tangier and the Cabezos Reefs”. It would stand 300 metres high, which Linger notes was more than 200 metres taller than any dam then in existence.
“Sorgel estimated that the dam would comprise some 10 billion cubic metres of material,” he notes.
Sorgel calculated that cutting off the Mediterranean would cause the sea to lower by 100 metres in the Gibraltar basin, and by 200 metres at the Sicily basin, creating the opportunity to generate massive amounts of hydro-electric power.
The lowering of sea levels would also create almost 600 square kilometres of new dry land for development, and link together the European and African continents.
Although the project didn’t go beyond the drawing board, it was taken seriously, as can been seen in the extensive Atlantropa archive in the Deutsche Museum in Munich, which contains architectural drawings for new cities, the dams and bridges, plus letters of support and hundreds of articles about the project, which appeared in the popular press and in specialised engineering and geographical magazines.
Herman Sorgel died on 25 December 1952. He was reportedly hit by a car while riding his bicycle, on a road “‘as straight as a die’, suggesting that he could have been murdered. The driver of the car was never found”.