to get rid of all the excess salt taken in by drinking seawater, you have to urinate more water than you drank.
Flooding can affect rivers because river flooding causes things to be picked up from the streets and pulled back into the water. So It affects the water quality and if anything dangerous to the fish and water life gets in the water it will mess up their life system. Hope this helped a little bit. :)
Tides have an effect on the waves and the moon has to do with both.
