Stream Order (Strahler)
Parameter Description: Stream order
Data Type: Line (stream layer)
Field Name: STRM_ORDER; Common Name: Stream Order (Strahler 1952)
Units: Classes, 1 – 7+
NetMap Module/Tool: Fluvial Processes/Network Variables
Model Description:
NetMap classifies streams according to stream order using the Strahler method (1957). The confluence of two first-order channels creates a second-order stream. Two second-order streams create a third-order channel, and so forth (see diagram, Figure 1). The intersection of lower order channels to a higher-order stream does not change the downstream order.
Note, stream order is sensitive to the upward extent of the channel network or locations of channels heads (e.g., number and density of first-order channels). Refer to ‘Analystic Stream Layer Derivation’ in the manual for additional information on NetMap’s state of the art stream layer.
Figure 1. NetMap contains a stream order parameter that can be displayed for the entire river network (shown above) or only for the defined fish bearing channels.