How does the Strahler stream order system categorize streams?

The Strahler stream order system categorizes streams based on their hierarchy in a watershed, focusing specifically on their origin and convergence. This system assigns a numerical order to streams, starting at the smallest headwaters. A headwater stream is categorized with an order of one. When two first-order streams converge, they create a second-order stream. If a second-order stream merges with another second-order stream, the resulting stream is given an order of three, and so forth. This methodology emphasizes the structural connectivity and relationship between different segments of a river system, illustrating how smaller tributaries contribute to larger rivers.

Other options, while undoubtedly related to streams in various contexts, do not pertain to the Strahler system's focus on stream order. For instance, temperature and flow rate are important factors for stream ecology but are not part of the stratification process in the Strahler system. Geographic location might affect various properties of streams but does not correspond to how the orders are designated. Pollutant levels are crucial for assessing stream health and water quality but do not serve as a basis for categorizing streams within the Strahler framework.