Types of Drainage System

Drainage systems can fall into several categories, depending on the topography and geology of the land. He outlines the types of drainage system as followings.

1.      Dendritic drainage system.

2.      Parallel drainage system.

3.      Trellis drainage system.

4.      Rectangular drainage system.

5.      Radial drainage system.

6.      Deranged drainage system.

7.      Annular drainage system.

Dendritic Drainage System 

Dendritic drainage system is the most common form of drainage systems. In a dendritic drainage system, there are many contributing streams (analogous to the twigs of a tree), which are then joined together into the tributaries of the main river (the branches and the trunk of the tree, respectively). They develop where the river channel follows the slope of then the terrain. Dendritic system form V-shaped valleys as a result, the rock types must be impervious and non-porous.

Parallel Drainage System

A parallel drainage system is a pattern of rivers caused steep slopes with some relief. Because of the steep slopes, the streams are swift and straight, with very few tributaries, and all flow in the same direction. This system forms on uniformly sloping surface, for example, rivers following southeast from the Abandare Mountains in Kenya.

Trellis Drainage System

The geometry of a trellis drainage system is similar to that of a common garden trellis used to grow vines. As the river flows along a strike valley, smaller tributaries feed into it from the steep slopes on the sides of the mountains. These tributaries enter the main river at approximately 90 degree angles, causing a trellis-like drainage system. Trellis drainage is characteristic of folded mountains, such as the Appalachian Mountains in North America. De Jong (1979).

Rectangular Drainage System

Rectangular drainage develops on rock that are of approximately uniform resistance -to erosion but which have two directions of jointing at approximately right angles. The joints are usually less resistant to erosion than the bulk rock so erosion tends to preferentially open the joints steams consist mainly of straight line segments with right angle bends, and tributaries join larger streams at right angles.

Radial Drainage System

In a radial drainage system the streams radiate outwards from a central high point. Volcanoes usually display excellent radial drainage. Other geological features the drainage may exhibit a combination of radial and annular patterns.

Deranged Drainage System

A deranged drainage system is a drainage system in drainage basins where there are no coherent pattern rivers and lakes. It happens in areas where there has been much geological disruption. The classic example is the Canadian Shield. During the last ice age, the topsoil was scraped off, leaving mostly bare rock. The melting of the glaciers left land with many irregularities of elevation, and a great deal of water to collect in the law point explaining the large number of lakes which are found in Canada. The water sheds are young and are still sorting themselves out. Eventually the system will stabilize.

Annular Drainage System

In an annular drainage pattern streams follow a roughly circular or concentric path along a belt of weak rock, resembling in plan a ring like pattern. It is best displayed by streams drainage a maturely dissected structural dome or basin where erosion has exposed rimming sedimentary strata of greatly varying degree of hardness, as in the red valleys, which nearly encircles the dome structure of the block hills of South Dakota. 

References

De Jong, M.H. (1979); “Drainage of Structured Clay Soil” Netherlands, Wageningen Publication.