Drainage System of India: Drainage Pattern Part-I

Drainage System of India: Drainage Pattern| Part-I

In this article, we will discuss the drainage system of India which is a very Important Topic in the Geography section for all civil services exam purposes. In this article, we will know, what is the drainage system and many more things about the drainage system. The drainage pattern of an area depends upon the geological time period, nature and structure of the rock, topography, slope, amount of water flowing, and the periodicity of the floor.

Drainage System: An Introduction

• The flow of water through well defined channels is known as drainage and the network of such channels is called drainage system.
• Drainage system is system of rivers which is spread over a particular area with specific water capacity
• The area drained by a single river system called drainage basin.
• Drainage basins are also known as catchment, catchment area, catchment basin, drainage area and river basin.

• The drainage pattern of an area depends upon geological time period, nature and structure of rock, topography, slope, amount of water flowing and the periodicity of the floor.
• The world's largest drainage basin is of Amazon River and the Ganga River has the largest basin in India.

Drainage System:

• Water Divide- Any elevated area, such as a mountain or an upland which separates two drainage basins. Such an upland is called a water divide.
• It is also called Drainage divide.
• Water divide is usually a ridge or a high platform.

Water divides in India:

In India, there are mainly four water divides:

• Aravallis- Water divide for Luni river
• Himalayas- Water divide for Indus river
• Satpura and Vindhya Range- Water divide for Narmada and Tapi
• Western Ghats- Water divide for peninsular rivers

Difference between river basin and watershed:

• Though both river basins and watersheds are areas of land that drain to a particular water body, such as a lake, stream, river or estuary.
• The term watershed is used to describe a smaller area of land that drains to a smaller stream, lake or wetland. There are many smaller watersheds within a river basin.
• Example: watershed of Yamuna + watershed of Chambal + watershed of Gandak + …. = Drainage basin of Ganga

• The catchments of large rivers are called river basins while those of a small rivulet and rails are known as watershed.
• Watersheds are small in area while the basins cover large area. 
• River basins and watershed are marked by Unity, what happens in one part of the basin or watershed directly affects the other parts and the unit as a whole. That is why, they are accepted as the most appropriate micro, meso or macro planning figure .

Drainage pattern:

There are various pattern which are followed by the various river basin in accordance with their water capacity and flow pattern.

1. Dendritic
2. Trellis
3. Angular
4. Rectangular
5. Radial
6. Annular
7. Parallel
8. Centripetal

Dendritic  Drainage Pattern:

• The drainage pattern resembling the branches of a tree is known as dendritic drainage.
• This is an irregular tree branch shaped pattern.
• There are many contributing streams, which are then joined into the tributaries of the main river.
• A dendritic pattern develops in a terrain which has uniform lithology, and where faulting and jointing are insignificant.

Examples: Rivers of northern Plains.

Trellis Drainage Pattern:

• When the primary tributaries of a river flow parallel to each other and secondary tributaries join them at right angles the pattern is known as Trellis.

Examples: The old folded mountains of the Singhbhum (Chotanagpur Plateau)

Angular Drainage Pattern:

• Angular drainage patterns form where bedrock joints and faults intersect at more acute angles than rectangular drainage patterns. Angles are both more and less than 90 degrees.
• This pattern is common in Himalayan foothill regions.

Rectangular  Drainage Pattern:

• Pattern formed in which the main stream bends at right angles and the tributaries join at right angles creating rectangular patterns.
• Example: Streams found is the Vindhyan Mountains.

Radial Drainage Pattern:

• When the river originate from a hill and flow in all directions, the drainage pattern is known as Radial drainage.
• Also known as  centrifugal pattern.
• A good example of a radial drainage pattern is provided by the rivers originating from the Amarkantak Mountain.
• Rivers like Narmada, Son and Mahanadi originating from Amarkantak Hills flow in different directions and are good examples of radial pattern.

Annular drainage Pattern:

• In an annular drainage pattern streams follow a roughly circular or concentric path along a belt of weak rock, resembling in plan a ringlike pattern. 
• Example: This is not a very common drainage pattern in India. Some examples of this are however found in Pithoragarh (Uttarakhand), Nilgiri Hills in Tamil Nadu and Kerala.

Parallel drainage pattern:

• Rivers flow parallel to each other for a long distance. E.g. River Ganga and Yamuna flow parallel to each other before joining at Allahabad.
• The tributaries seem to be running parallel to each other in a uniformly sloping region.
• Example: Rivers of lesser Himalayas and rivers originating in the Western Ghats that flow into Arabian Sea.

Centripetal drainage pattern:

• When the rivers discharge their waters from all the directions in a lake or depression the pattern is known as centripetal drainage.
• Examples: Streams of Ladakh, Tibet, and the Baghmati and its tributaries in Nepal.

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