PPT: Drainage System | Geography for UPSC CSE PDF Download

 Page 1


Drainage System Of 
India
Page 2


Drainage System Of 
India
Some basic 
terms
? Source of a river: The beginning or start of a river.
? Confluence: The point at which two rivers or 
streams join.
? Distributary: The small river that branches out 
from the main river and then never meets again. It 
thus decreases the river’s water volume. 
Distributaries are commonly found on deltas but 
are also important in the formation of alluvial fans 
and cones.
? Tributary: A stream or smaller river which joins a 
larger stream or river and thus increases its water 
volume.
Page 3


Drainage System Of 
India
Some basic 
terms
? Source of a river: The beginning or start of a river.
? Confluence: The point at which two rivers or 
streams join.
? Distributary: The small river that branches out 
from the main river and then never meets again. It 
thus decreases the river’s water volume. 
Distributaries are commonly found on deltas but 
are also important in the formation of alluvial fans 
and cones.
? Tributary: A stream or smaller river which joins a 
larger stream or river and thus increases its water 
volume.
River basin, 
catchment 
area and 
watershed
? River Basin: All the area drained by a river and its 
tributaries.
? Catchment area: It refers to all the area of land over 
which rain falls and is caught to serve a river basin.
? The catchment area of large rivers or river system is 
called a river basin while those of small rivers, a lake, a 
tank is often referred to as a watershed. Watersheds 
are small in area, generally less than 1000 ha.
? There are many smaller watersheds within a river 
basin. Example: watershed of Yamuna + water shed of 
Chambal + watershed of Gandak + …. = Drainage basin 
of Ganga.
Page 4


Drainage System Of 
India
Some basic 
terms
? Source of a river: The beginning or start of a river.
? Confluence: The point at which two rivers or 
streams join.
? Distributary: The small river that branches out 
from the main river and then never meets again. It 
thus decreases the river’s water volume. 
Distributaries are commonly found on deltas but 
are also important in the formation of alluvial fans 
and cones.
? Tributary: A stream or smaller river which joins a 
larger stream or river and thus increases its water 
volume.
River basin, 
catchment 
area and 
watershed
? River Basin: All the area drained by a river and its 
tributaries.
? Catchment area: It refers to all the area of land over 
which rain falls and is caught to serve a river basin.
? The catchment area of large rivers or river system is 
called a river basin while those of small rivers, a lake, a 
tank is often referred to as a watershed. Watersheds 
are small in area, generally less than 1000 ha.
? There are many smaller watersheds within a river 
basin. Example: watershed of Yamuna + water shed of 
Chambal + watershed of Gandak + …. = Drainage basin 
of Ganga.
Drainage 
patterns
Drainage 
patterns
Discordant 
Drainage
Antecedent Superimposed
Concordant
Page 5


Drainage System Of 
India
Some basic 
terms
? Source of a river: The beginning or start of a river.
? Confluence: The point at which two rivers or 
streams join.
? Distributary: The small river that branches out 
from the main river and then never meets again. It 
thus decreases the river’s water volume. 
Distributaries are commonly found on deltas but 
are also important in the formation of alluvial fans 
and cones.
? Tributary: A stream or smaller river which joins a 
larger stream or river and thus increases its water 
volume.
River basin, 
catchment 
area and 
watershed
? River Basin: All the area drained by a river and its 
tributaries.
? Catchment area: It refers to all the area of land over 
which rain falls and is caught to serve a river basin.
? The catchment area of large rivers or river system is 
called a river basin while those of small rivers, a lake, a 
tank is often referred to as a watershed. Watersheds 
are small in area, generally less than 1000 ha.
? There are many smaller watersheds within a river 
basin. Example: watershed of Yamuna + water shed of 
Chambal + watershed of Gandak + …. = Drainage basin 
of Ganga.
Drainage 
patterns
Drainage 
patterns
Discordant 
Drainage
Antecedent Superimposed
Concordant
Antecedent 
Drainage or 
Inconsequent 
Drainage
?A part of a river slope and the surrounding 
area gets uplifted and the river sticks to its 
original slope, cutting through the uplifted 
portion like a saw [Vertical erosion or 
Vertical down cutting], and forming deep 
gorges: this type of drainage is called 
Antecedent drainage.
?Example: Indus, Sutlej, Brahmaputra and 
other Himalayan rivers that are older than 
the Himalayas themselves. There are 
usually called as ANTECEDENT RIVERS.