UV Texturing a hillside scene - River?

I have modeled a hilltop scene for my game, and now want to UV map it. I select all faces, unwrap, then choose the script for ‘Export UV Face Layout’. This does not work, returning an .svg file of a black box?!?!

Even if it did work, how would I determine where the river was? From top parallel view in the UV editor my scene is a grid, so I have no chance of guessing where the river was!

What should I do?

I’ve included is the .blend file.

Thanks

Attachments

Hilltop.blend (508 KB)

Unwrap the river separately. Select all the faces of the river and and do an unwrap on just them.

Thanks a lot.