Human impact on Earth’s freshwater resources revealed

Today's Video of the Day from NASA Goddard reveals the surprising influence that humans have on Earth's freshwater resources. In the first study to assess seasonal variability in water bodies worldwide, researchers have discovered that water levels in human-managed reservoirs fluctuate about four times more compared to natural lakes and ponds.  "We tend to think of the water cycle as a purely natural system: Rain and snowmelt run into rivers, which run to the ocean where evaporation starts the whole cycle again," said …