Measure of the position of a stream (defined as the reach between successive tributaries) within the hierarchy of the drainage network. A commonly used approach allocates order ‘1’ to unbranched tributaries, ‘2’ to the stream after the junction of the first tributary, and so on. It is the basis for quantitative analysis of the network.
Stream order
A method of classifying the different segments of a drainage system in order to investigate any possible relationship between these segments. Horton (1945), Geol. Soc. Amer. Bulln. 56, 3, 275 promoted stream ordering, but it is Strahler’s modification of Horton’s ordering system (Strahler (1957), Trans. Amer. Geophys. Union 38, 6, 913) that has been most widely adopted. Gilvear and Jefferies in J. Holden (2005) find that ‘despite the variable size and nature of stream patterns, each network has been found to have an ordered internal composition’. See also bifurcation ratio.
Stream order
- OOP
- Oort Cloud
- Oort cloud
- Oort, Jan Hendrik
- Oort, Jan Hendrik (1900–1992)
- Oort’s constants
- oosparite
- oosphere
- oospore
- Oosterhoff group
- Ootacamund Radio Astronomy Centre
- ootid
- ooze
- OP
- Op
- opacity
- opacity and transparency
- opacus
- opal
- opalescence
- op-amp
- opaque mineral
- opaque policy measures
- op code
- op-code