Germany had plans to build a dam at the strait of gibraltar if they won the war, guess it was something to do with that

Atlantropa, it was a plan to dam the strait of gibraltar and drain the mediterranean for farmland. They tried it in TNO, but it failed miserably (as it would have IRL). That's also why there's a giant lake in the middle of Africa.

Would also explain why the opening to the Black Sea is closed too.

It's not the actual Bosphorus that is closed but parts of the Aegean dried up in the damming process of strait of Gibralter leading to no more water there.

Originally posted by Cookertron:

Germany had plans to build a dam at the strait of gibraltar if they won the war, guess it was something to do with that

Germany didn't have plans to build a dam. It was promoted by basically one weird architect guy in the 1920's and 1930's.
The nazis would have no reason to start the project, as they had lebensraum in the east, why waste money on more in the south, for the italians? There'd be way more problems than that too.

The Reich went ♥♥♥♥♥♥♥ insane after winning the war ITTL. It's one of the reasons why their economy crashes.

Atlantropa was designed to create an infinite source of power by making that small opening at Gibraltar a hydroelectric dam. The Mediterranean losing its water levels that much would be the price, but the intentions were justified, imagine how Europe would look if they had an infinite source of power and electricity. The idea originated by a German architect who presented it himself, it especially gained popularity in the 30s and 40s when the Nazis took over and were obsessed with innovations for multiple reasons. The Architect also saw this as a way to show the world that humanity can use its new technological abilities for peaceful reasons rather than machines of war. Unfortunately the idea vanished from the public soon after his passing because he was the only one who cared about it. but in this scenario, it is very well possible that he could convince the Nazis to complete his project after they won the war. And he is probably still alive in this version happy with himself that his life's work is complete.