In so many ways, the earth’s water cycle explains so many of the water-related problems we face today.

And, in recent years, we humans have had a greater and greater impact on the water cycle.

About one-fifth of the world’s population now live in regions of physical water scarcity. As sources run dry, these regions cannot meet human or environmental water demands.

In recent years, some of the world’s greatest rivers have dried up. This includes the Rio Grande and Colorado Rivers in the U.S., the Yaqui River in Mexico, the Indus River in Pakistan, the Ganges in Bangladesh, the Yellow and Tarim Rivers in China, and the Murray Rivers in Australia, along with others.

The causes? Drought, climate change, and, most notably, human demands. It wouldn’t be an exaggeration to say that agriculture is sucking the Colorado and Rio Grande Rivers dry.

Another quarter of the world’s population live in regions lacking the infrastructure needed to collect water from rivers and aquifers.