[webmaven]

It's not a stupid idea, but you need a rather large height difference to make such a project viable.

The Dead Sea, which at 1,200 feet below sea level is the lowest spot on the planet, had a proposed project taking water from the Mediterranean in the 80's [1], and has a current project taking water from the Red Sea [2].

The current project is slated to break ground in 2018. There is no way that several hundred million cubic meters of water per year will put so much as a measurable dent in global sea levels (there is some minor concern that there will be some environment impact on the Red Sea, but in- and out-flows between the Persian Gulf and the Red Sea dwarf the volume expected to be extracted for the project by several orders-of-magnitude.

So: Good idea, has potential for hydroelectric power in various locations around the globe, but no matter what won't affect sea levels at all, unfortunately.

[1] https://en.wikipedia.org/wiki/Red_Sea%E2%80%93Dead_Sea_Water...

[2] https://en.wikipedia.org/wiki/Mediterranean%E2%80%93Dead_Sea...