Well, wikipedia says that tidal waves are formed by the incoming water of the rising tide. Usually tides take 6 hours to rise fully, on the open coast, but in an narrowing estuary the water can bunch up and actually form a sudden step. This is not a boat wake (too wiggly), and it goes all the way across the river, so it does suggest the whole river depth is changing. However, I'm not 100% convinced that this is indeed a tidal wave, because of the lighting. I get the feeling that there's a...
AlejoHausner: Comments
See "Landsberg" on wikipedia.
Alejo
http://maps.google.com/maps?hl=en&t=k&q=Brazil&ie=UTF8&ll=-19.600749,-43.193479&spn=0.013665,0.020449&om=1
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