The role of drainage analysis in biological work on streams

Summary

Drainage analysis is the quantitative study of various characterstics of drainage nets, based on a scheme of classification in which small, unbranched tributary streams are called first order. Higher orders are formed wherever equal-rder streams join. A concept of “biological significance” must be established before ecologic use can be made of this idea, however. In addition, a new way of totaling the streams in each order, based on the idea that the first order stream is equivalent to the section (called a “drainage unit”) between any two tributaries rather than to the whole higher order stream, is needed and here proposed. Data confirming its approximate equivalence throughout a system are shown for a hill-stream in Vermont.