1. Create map with huge number of rivers but no water body - no rivers will appear
2. Dig hole to water near border of the map.
3. Fence it with power line
4. Resize map - game will crash with vector template ****ertion
(http://mallorn.ii.uj.edu.pl/~amelek/enlarge.JPG)
Some time ago, instead of crashing, game would make a river under power line, but due to impossibility of lowering terrain, it will instead build river that goes up the hill. Crash might be related with fix to this issue.
(http://mallorn.ii.uj.edu.pl/~amelek/enlarge2.JPG)