One of the biggest reasons was that there were some revolutions that happened around the lat 19th century. They were primarily sparked by lower class individuals who were looking for more money to support themselves/families.
Usually it is fresh. There are exceptions: The Dead Sea (37% salinity) is so salty barely lives in it and the Salt lake near Salt Lake City is so salty people can easily and comfortably float in it.
Seaworks prevent flooding and are useful.
True. Terrorists are usually driven by religions, political and power motivations.
Hope this helps!
