How has europe been affected by its many rivers

Europe has benefitted greatly from its many rivers since they not only provide a source of water that aids in crop growth, but they also provide natural barriers to block against foreign invaders. 

I'd say that lighting hitting land would be more dangerous. If it hit water it would more than likely not affect anything besides a fish if it was within the vacinity. A lighting stroke on land though is more likely to hit a person than a lighting strike in water is to hit a person or a fish for that matter.

Hope this helps =)