Newcastle University

Strahler stream order

What do you mean by stream order?

Stream order is used to define stream size in a drainage basin based on the hierarchy of tributaries.

The Strahler stream order is the most common stream ordering method. When two first-order streams join then they create a second order stream. When two second-order streams join together they form a third order stream (and so on). The schematic below illustrates this:

This means that a stream which has a Strahler stream order of 1, it does not have any tributaries. One with 12 would be very powerful and a very large drainage basin.

What does stream order tell us?

Stream order is very useful to know when managing watercourses and understanding which tributaries have a higher risk of flooding - will water be concentrated in one channel or spread out?

What about the Strahler stream order in the Haltwhistle Burn catchment?

The interactive map below shows the stream ordering for the Haltwhistle Burn catchment: