Most of our earth is covered in water. Without water, no life. The water on our earth is in a constantly renewed global cycle. By evaporation the water gets into the atmosphere, by atmospheric circulation the evaporated water is further transported across long distances and returns to the earth as precipitation. Climate change, however, alters this hydrological cycle. Climate change intensifies the disparities in the global water supply and increasingly causes droughts and floods, respectively.
We speak of low or high water when it falls below or rises above the average water level considerably.