Drainage Patterns and Morphometry

Drainage Morphometry: Stream Ordering

Denver Kunaka Last edited:November 10, 2020

Table of Contents

Morphometry is the study of shape or form of different landforms.

Stream Ordering

Stream order shows the hierarchical linkage between streams within a drainage basin. Two methods of stream ordering is the Shreve method and the Strahler method. The latter method is the most widely used.

Strahler’s Method

Strahler states that when first order streams i.e streams without any tributaries join they form second order streams. When second order streams meet a third order stream is formed and so on.

However, when two streams of different order meet the stream of higher order will take precedence eg when second and third order streams meet the higher third order stream will take precedence.

Stream Ordering
Strahler’s Stream Order

Shreve’s Method Shreve’s method takes into account stream magnitude. When two streams join they are added together eg third and second magnitude streams will add to give a fifth magnitude stream.

In the Shreve method magnitude increase at all junctions unlike the Strahler method where the stream with the highest order is taken when two streams of different order meet.

Shreve Stream Magnitude
Shreve’s method of stream magnitude

Bifurcation Ratio

Bifurcation ratio is the ratio of lower order streams to higher order streams. This means that we divide the total number of first order streams by the total number of second order streams, second order streams by the total of third order streams and so on.


N1/N2
N2/N3
N3/N4
and so on.
If we need to find the average bifurcation ratio we simply:
N1/N2 + N2/N3 + N3/N4 / 3.

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About Author

Denver is a Geographer, Web Developer, Graphic Designer, Blogger & Digital Marketer. He has come to know that everyday there's something new to learn :-)