They do resemble topographical maps, yes, but these aren't topographical. If they were, the landmasses would also have lines all over them.
The lines in the water are representative of surface water formations.
But it doesn't hurt that they evoke the image of topography.
[edit] Your tone seems to suggest, by the way, that my style shouldn't be topographical, or that if it is topographical, it isn't "my" style. I must admit that I'm a little baffled by this point of view.