DRAINAGE BASINS AND STREAM PATTERNS compiled by PIBANTU.

1. DRAINAGE BASINS AND
STREAM PATTERNS
GRADE 12: GEOMORPHOLOGY
GEOGRAPHY TERM TWO

2. AT THE END OF THESE SLIDES, YOU
SHOULD BE ABLE TO
 Define what a drainage basin is
 List and identify characteristics of a drainage basin
 Define what a stream pattern is
 List and identify the different types of stream
patterns
 Discuss factors that influence the characteristics of
different stream patterns

3. WHAT IS A DRAINAGE BASIN?
 is an area of land from which all precipitation (such as
rainfall or snowmelt) drains into a common outlet, such
as a river, stream, lake, or ocean.
 It is a natural hydrological feature that encompasses the
entire network of water bodies, including rivers, streams,
and their tributaries, as well as the surrounding land that
contributes water to those water bodies.

4. FEATURES OF A DRAINAGE BASIN

7. DISCUSSION:
 Why do you think drainage basins important in
understanding the movement of water on the
earth's surface?

8. STREAM PATTERNS
 Stream patterns refer to the shape and
configuration of a river or stream channel
and its associated features.
 Streams can take on different patterns,
depending on factors such as the underlying
geology, topography, climate, and land use.

9. TYPES OF STREAM PATTERNS

10. 1. DENDRITIC STREAMS
 These streams have a branching, tree-like pattern, with
smaller tributaries feeding into larger, main channels.
 Dendritic streams are common in areas with uniform geology
and topography, such as in flat, sedimentary basins.

11. DENDTRIC STREAM PATTERN

12. 2. RECTANGULAR STREAMS
 occurs when the rock structure steers streams into a
parallel course, with tributaries joining at almost right
angles.

13. RECTANGULA STREAM PATTERN

14. 3. PARALLEL STREAMS
 are a type of stream pattern characterized by multiple streams
running roughly parallel to each other.
 In this pattern, the streams maintain a consistent direction and
spacing between them.
 Parallel streams often develop in regions with parallel or sub-
parallel geological structures, such as tilted sedimentary rock
layers or fault lines.

15. PARALLEL STREAM PATTERN

16. 4. TRELLIS STREAMS
 A trellis stream pattern is a type of drainage pattern
characterized by a network of parallel main streams with
shorter tributaries flowing perpendicular into them.
 This pattern resembles a trellis, which is a framework of
intersecting lines or bars.

17. TRELLIS STREAM PATTERN

18. 5. DERANGED STREAMS
 refers to a type of stream network that lacks any discernible
pattern or organization.
 In a deranged pattern, streams and rivers flow in various
directions without a clear hierarchical arrangement or
consistent alignment.

19. 6. RADIAL STREAMS
 Radial streams originate from a central high point and flow
outward in different directions, similar to the spokes of a
wheel.
 This pattern is often seen in volcanic or mountainous regions
where streams radiate from a central peak or crater.

20. FACTORS INFLUNCING THE
CHARACTERISTICS OF STREAM PATTERNS
 The underlying geological features, such as rock type, structure,
and resistance to erosion
 Vegetation, including forests, grasslands, and wetlands, affects
stream patterns in several ways and plays a role in shaping
stream patterns.
 The slope and elevation of the land affect stream patterns.
 Climate and precipitation patterns influence stream patterns
through the amount, intensity, and seasonal distribution of
rainfall.
 The composition, texture, and permeability of soil and sediments
in a watershed can impact stream patterns.

21. HUMAN FACTORS
 Urbanization
 Deforestation
 Agriculture
 Channel modifications

22. DISCUSS:
 HOW DO YOU THINK DEFORESTATION
HELPS ALTER OR DEFINE A STREAM
PATTERN?

23. NATURAL DISASTERS?
 Events like floods or landslides can have a
significant impact on stream patterns.
 Intense flooding can reshape stream channels,
altering their patterns and routes.

24. FOR ADDITIONAL INFORMATION:
 https://www.youtube.com/watch?v=SCFcSLAwB30
&pp=ygUhZHJhaW5hZ2UgYmFzaW4gZ2VvZ3Jhc
Gh5IGdyYWRlIDEy
 https://www.youtube.com/watch?v=OI-
M1li9N4M&pp=ygUhZHJhaW5hZ2UgYmFzaW4gZ
2VvZ3JhcGh5IGdyYWRlIDEy