Water always seeks it's own level.
The Great China Canal built from 500 bc- 1200 ad is over 1100 miles long with 24 locks(46 miles avg.), like the Suez Canal with NO Locks 100 miles built on a consistent datum line in 1859. Both these miracles of engineering are flat as a pancake and in no way follow some hocus pocus curvature lie. The Suez would have a bulge at the top of over 1,600 ft of desert not water as it would have flowed back into the Mediterranean Sea or Gulf of Suez.