Drainage patterns are formations created by streams, rivers, and lakes within a drainage basin, influenced by geological factors and topography. Various types of drainage patterns include dendritic, rectangular, angular, parallel, trellis, annular, radial, centripetal, barbed, and deranged, each exhibiting unique characteristics based on the geological structure of the region. Understanding these patterns is crucial as they reflect the geological history and modifications of an area, offering insights into the underlying geologic structures.

1. DRAINAGE PATTERNS
Hydrology and Fluvial Morphology

2. Mashrup Hasan | GEE | SUST

3. What is
Drainage Pattern?
Drainage pattern is the pattern
formed by the streams, rivers,
and lakes in a particular
drainage basin. The drainage
pattern of an area is the outcome
of the geological time period,
nature and structure of rocks,
topography, slope, amount of
water flowing and the periodicity
of the flow.

4. How are
Drainage
Patterns formed?
Drainage channels develop where surface runoff is
enhanced, and earth materials provide the least
resistance to erosion. Their patterns develops in
response to the local topography and subsurface
geology.

5. Types of Drainage
Pattern
Dendritic Rectangular Angular Parallel Trellis
Annular Radial Centripetal Barbed Deranged

6. Dendritic pattern
A dendritic drainage pattern is
the most common form and looks
like the branching pattern of
tree roots. It develops in
regions underlain by homogeneous
material. That is, the
subsurface geology has a similar
resistance to weathering so
there is no apparent control
over the direction the
tributaries take.

7. Rectangular
pattern
Rectangular pattern is drainage
pattern in which the main streams
and their tributaries display many
right-angle bends and exhibit
sections of approximately the same
length. The rectangular drainage
pattern is found in regions that
have undergone faulting. Streams
follow the path of least
resistance and thus are
concentrated in places where
exposed rock is the weakest.
For example, in Bangladesh the
rectangular drainage pattern is
mostly seen in the eastern hilly
region where sedimentary rocks are
very much controlled by structural
features like faults and joints.

8. Angular drainage patterns
form where tributaries and
mainstreams joins 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.
Angular pattern

9. Parallel pattern
Parallel drainage pattern
is a pattern of rivers
caused by 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.
For example, in Bangladesh
The Dharla and Dudhkumar
flow parallel to Tista.

10. Trellis
Pattern
Trellis Drainage Pattern
looks similar to the
common garden trellis.
These develop where
sedimentary rocks have
been folded or tilted and
then eroded to varying
degrees depending on
their strength.
Tributaries join at high
angles often right

12. Annular
Pattern
An Annular Drainage
Pattern is a drainage
pattern in which streams
flow in a nearly
circular or concentric
pattern along with a
weak rock band,
resembling a ring in the
plane. This pattern
typically develops in
domes.

13. Radial pattern: Centripetal pattern:
When the rivers originate from a hill and flow in
all directions, the drainage pattern is known as
'radial’. The radial drainage pattern develops
around a central elevated point and is common
to conically shaped features such as
volcanoes.
Centripetal drainage pattern is formed when rivers
discharge their waters from all directions into a
lake or a depression. This is the opposite of a radial
pattern, and here the rivers drain in towards the center
of a basin, like the spokes of a wheel.

14. Barbed Drainage
Pattern
Barbed is the result of
capture of the main
river which completely
reverses its direction
of flow, while the
tributaries continue to
point in the direction
of former flow.
Arun River (Nepal) is a
good example of this
type of drainage
pattern.

15. Deranged drainage
pattern
Deranged drainage system is a
drainage system in drainage
basins where there is no
coherent pattern to the rivers
and lakes. It happens in areas
where there has been much
geological disruption.

16. Why is
drainage
pattern
important?
The patterns which streams form are
determined by inequalities of surface slope
and rock resistance. This being true, it is
evident that drainage patterns may reflect
original slope and structure or the
successive episodes by which the surface
has been modified, including uplift,
depression, tilting, warping, folding,
faulting, and jointing, as well as
deposition by the sea, glaciers, volcanoes,
winds, and rivers.
Since drainage patterns are the reflection
of so many factors, it is evident that they
form one of the most immediate approaches
to an understanding of geologic structure.

17. Thank you.