Drainage basins can be characterized by comparing a number of easily measured morphometric parameters, including the number of streams of each stream order, stream lengths, average slope, and drainage area. Each stream basin will have its own set of values. Basins can be compared with one another according to their morphometric parameters.
The following parameters yield geometric (non-linear) series. They are usually plotted on semi-log graphs to yield a straight line. The slope and intercept of the line are characteristic of the basin.
Drainage density is a measure of how closely spaced streams and ravines are in a drainage network. The drainage density depends on the slope, rainfall, vegetation, physical properties of the soil, sediments, and rock and other factors that determine the erosive energy of the surface runoff and the resistance to erosion of the surface materials.
Drainage Density = (sum of stream lengths) / (basin area)
Dd = L / A
|
hypothetical morphometric parameter values
(Easterbrook, 1993) |
||||
| stream order | number of streams | average length (km) | average slope | average drainage (sq km) |
|
1
|
243
|
1
|
0.3333
|
2
|
|
2
|
81
|
1.6
|
0.1111
|
4
|
|
3
|
27
|
2
|
0.0370
|
8
|
|
4
|
9
|
4
|
0.0123
|
16
|
|
5
|
3
|
8
|
0.0041
|
32
|
|
6
|
1
|
16
|
0.0014
|
64
|