CBSE Class 9 Answered

The following are the four major drainage patterns:

Dendritic: This drainage system is formed when the river channel follows the slope of the terrain. Because many tributaries join the main river, this drainage system appears like the branches of trees. 

Trellis: The trellis pattern is developed when many tributaries join the main river at right angles and the hard and the soft rock exist parallel to each other.  

Rectangular: It develops on the strongly jointed rocky terrain which are resistant to erosion. Such rocks have joints at right angles which can be eroded. The joints are cracked opened by erosion, and hence, the streams of rivers develop along these joints. 

Radial:  When the streams of rivers flow in different directions from a central peak or a dome-like structure, the radial drainage pattern is developed.