The streams range from one (1) to the most powerful which is the Amazon River at "12." The Ohio River is an "8" and the Mississippi River is a "10." 80 percent of the streams and rivers on the planet are first or second order.
To qualify as a stream it must be either recurring or perennial. Recurring streams have water in the channel for at least part of the year. When two first-order streams come together, they form a second-order stream. When two second-order streams come together, they form a third-order stream. Streams of lower order joining a higher order stream do not change the order of the higher stream. Thus, if a first-order stream joins a second-order stream, it remains a second-order stream. It is not until a second-order stream combines with another second-order stream that it becomes a third-order stream.
Arthur Newell Strahler first proposed the hierarchy in 1952 in an article “Hypsometric (area altitude) analysis of erosional topology.” in the Geological Society of America Bulletin. It is often referenced in professional descriptions of rivers as Strahler 1952.
If the network is "broken" (arcs not connecting) then the output will be incorrect. The algorithm would treat the disconnected catchment as a separate river system, so it is important to check the connectivity of your river network before attempting to compute Strahler order values.
Linkages between Trophic Variability and Distribution of Pteronarcys Spp. (Plecoptera: Pteronarcyidae) along a Stream Continuum
Apr 01, 1998; ABSTRACT.-Pteronarcys stoneflies, which are traditionally considered shredders in eastern North America, inhabit second- through...