Maps are where water system thinking, and the analysis that must precede all our efforts to manage our water resources, must begin.

From a single large regional hydrologic unit, from which a city may plan to satisfy the needs of it's people, to the world's great water regions, it is maps that help us to start understanding what is really going on.

A good example of the mapping of a single unit the graphic portion of the Edwards Aquifer in central Texas.

Taking a more global view leads us to this map of all the world's major water regions, from the Global International Waters Assessment (GIWA), is a good place to start.

This type of a geographic breakdown then allows us to focus our attention on the many specific places where there are things of potential interest to water planners going on. In terms of visualizing where in the world there are critical water issues, this site of the United Nations Environmental Program (UNEP) is one of the best.