It can be called Gestalt, where your brain finishes/completes what is left out. We all know what a whole water tower looks like. Hell, Dikkie even has an example of a whole tower reflected in the water. The fact he intentionally cut off the top of the tower makes one wonder, why? There is a great deal of left/right symmetry in the image, the water tower not only breaks up the symmetry but does so while being incomplete. All that green and blue of nature, has been disrupted by an incomplete man made object. This is largely a serene scene with gently undulating bands of blue, green and brown flowing across the frame. The serenity is abruptly interrupted by the water tower. Had it been a complete tower and had it been comfortably placed in the frame ... I would had fallen back asleep. My first thoughts were to mentally center the tower for symmetry or move it to the left a bit for balance. Then I noticed the top chopped off and I really woke up wondering why and I can see a fuzzy copy of the tower top in the water ... so now I'm looking closely at the water ... I can go on, but you get the point. The slightly awkward placement of the tower and it's scalping adds significant interest and tension to an otherwise sleepy composition and subject.
Should this technique be used in every photo ... no. Does it work in this case ... yes.
Well done Dikkie, and a good call to use these techniques on this image.