A hydrologic divide is the line of high ground that separates the watersheds of two streams; any given divide can be subdivided into the contributions made by the watersheds of each stream's tributaries. For example, in northern Colorado, the Continental Divide separates the watersheds of the Missouri and Colorado Rivers; each of these major watersheds is composed of secondary watersheds that rise along the Continental Divide (e.g. the South Platte and North Platte watersheds of the Missouri River system) and each of those secondary watersheds are composed of tertiary watersheds; such division can continue down to the watersheds of the smallest creeks and rivulets that rise along that segment of the Continental Divide.
The geometry of divide networks coincides with the nature of the landscape. A typical mountain range harbors a divide that runs along it crest which radiates divides to either side, separating the watersheds of the streams that drain its flanks. The divides of a mesa or plateau generally radiate out from central high ground, separating the watersheds of the streams that rise atop the tableland and drop along its walls. While the divides of mountain ranges and plateaus often zig-zag along the crest and side ridges, divides in flat landscapes tend to run in a parallel or gradually converging formation.
One need not visit dramatic natural landscapes to study divides. Indeed, they run through our towns and cities as well, separating the various creek watersheds that cover our home area; in fact, should you live on a ridge (however modest) between stream valleys, a divide may run through your property. Those of us who are fascinated by geography and topography realize that an appreciation for divides and watersheds is key to understanding any landscape.
