There aren’t too many things more important to human survival and environmental health than watersheds. As much as any other criteria, the boundries of watersheds delineate the eco-regions where we are either meeting or failing to meet the challenge of preserving and cleaning up our ecosystems. Do you want to monitor and manage global climate change? Don’t forget to follow the watersheds - because the hydrological cycle of our planet, and ultimately, our ability to store and manage fresh water - comes down to how we manage each and every individual watershed on earth.

Some of the world’s greatest ecological disasters as well as some of the greatest opportunities lie in how we manage (or mismanage) our watersheds. Diversions from the Syr Darya and Amu Darya river for cotton irrigation has caused the Aral Sea to dry up. Diverting excess water from the Volga watershed might help us fill the Aral Sea back up. Who knows, maybe diverting excess water from the Ubangi watershed (a northern tributary of the Congo) might help us fill back up Lake Chad.

The Water Resources eAtlas is a fantastic website that shows in useful detail every major watershed on earth. For example, here are the watershed maps for the Syr Darya, the Amu Darya, the Volga, and the Ob-Irtysh. These maps include land cover and use variables, population density and political boundries, and basic indicators such as area, water supply per person, number of dams, and biodiversity information. They also provide links to the sources for their data. For a good synopsis of how these watersheds could be interlinked to save the Aral Sea, read “Refill the Aral Sea” and “Arctic to Aral - Siberian Rivers Save the Aral Sea.”