Following up on my Martian canals theme from this question and assuming the canals can be constructed, I would now like to ask what level of technology is required to do that.
The basic problem
The Martians need very long and very large canals. Ideally 2000m wide, 100m deep and several thousand km long. Some leakage is to be expected but this should be minimised.
The real problem
What level of technology is required to do this? I need to know by rough technological age or by specific technological innovation if it’s important. Ideally I would like an ancient civilization to do this but I realize that this may be beyond their means.
Although I entioned Martians above, for simplicity you can assume an earth like world but with much less water suffering from increasing amounts of what little water there is being increasingly locked up at the poles, hence the need for the canals. Assume a whole world construction effort can be marshalled for this project. The project can be completed in stages and may take many decades, or even a few centuries if necessary.
What I’m trying to do is to make a realistic back story. My real story takes place on the canal network later after the original civilization of builders has disappeared or degenerated. I have borrowed a lot of this from Frank Chadwick's imaginary world of Space 1889 (although I’m not building a steam punk world).