Recognition of the river as the dominant force in forming basins may be traced back to John Playfair in 1802. In contrast to the leading opinions, Playfair observed that rivers were proportional to valley size and tributaries were accordant, neither of which would be likely unless rivers had created the basins, rather than the other way around. Now known as Playfair's law, his observation has led to extensive efforts to quantify river basin characteristics.

In 1945, R. E. Horton developed the concept of stream order, and Arthur Strahler further elaborated on the subject. The smallest tributaries are labeled "1," and when two first order streams converge, they form a second order stream ("2"), and so forth. The ratio of lower order to higher order streams remains remarkably consistent throughout a given basin. Uniformity is the important factor in all of these because it demonstrates that drainage network characteristics are quantitatively...