Class 9 Geography


Drainage: The river system of an area is called drainage. The area drained by a single river system is called the drainage basin.

Types of Drainage Pattern

(1) Dendritic Drainage Pattern, (2) Trellis Drainage Pattern, (3) Rectangular Drainage Pattern, (4) Radial Drainage Pattern

Drainage Patterns

Depending on the slope of land, underlying rock structure and climate of an area, the streams in a drainage basin form certain patters. Different types of drainage pattern are as follows:

  1. Dendritic Drainage Pattern: When the river channel follows the slope of the terrain, it develops dendritic pattern. The stream and its tributaries resemble the branches of a tree. Hence, it is called dendritic pattern.
  2. Trellis Drainage Pattern: When a river is joined by its tributaries at almost right angles, it develops a trellis pattern. Trellis pattern develops where hard and soft rocks exist parallel to each other.
  3. Rectangular Drainage Pattern: When rocks are strongly joined, then rectangular pattern develops.
  4. Radial Drainage Pattern: When the streams flow in different directions from a central peak or dome like structure, a radial pattern is developed.

It is important to note that a combination of different patterns may develop in the same drainage basin.

The drainage systems in India can be divided into two major groups, viz. the Himalayan Rivers and the Peninsular Rivers.

The Himalayan Rivers:

Most of the Himalayan Rivers are perennial, i.e. they have water throughout the year.

A river along with its tributaries forms a river system. There are three river systems in the Himalayas, viz. Indus, Ganga and Brahmaputra River Systems.

The Indus River System

Indus River System Map