Mountains and freshwater

Mountains and freshwater

Mountains are often called nature's water towers. They intercept air circulating around the globe and force it upwards where it condenses into clouds, which provide rain and snow.

Mountains also store water in various ways, including the formation of snow and ice which is later released as melt-off during warmer periods (often those with the lowest rainfall).

It is no surprise then that in semi-arid and arid regions, over 70 to 90 percent of river flows come from mountains. But even in temperate areas, 30 to 60 percent of freshwater can come from highland watersheds. In the Rhine basin, for example, the Alps provide 31 percent of annual flows — in summer more than 50 percent — even though they make up just 11 percent of the basin's land area.

In fact, all the major rivers in the world — from the Rio Grande to the Nile — have their headwaters in mountains and one of every two people on the planet depends on mountain water in one way or another: for drinking, as a source of energy or income, for growing food.