Streams shape the land through erosion and deposition via fluvial processes. A stream system typically has three courses - upper, middle, and lower. The upper course has steep valleys and gorges due to erosion. The middle course features meandering streams and floodplains. The lower course is dominated by depositional landforms like deltas. A stream erodes until it reaches its base level, which can be an ocean, lake, or resistant rock layer.

1. Fluvial ProcessesFluvial Processes
and Landformsand Landforms
Stream systems

2. StreamsStreams
Flowing water exerts great influence in
shaping landforms.
Water is more effective than any other
gradational process
Running water modified existing landforms
through erosion and deposition.
Water flows overland surface or in
confined channels.

3. Stream SystemStream System
Streams
are bodies of water that flow in
well defined channels.
In Earth Sciences the Term
Stream means water flowing in
natural channel of any size.

4. ProcessesProcesses
Processes associated with work of streams.
These are known as Fluvial Processes.
From Latin means Fluvius, river.

5. Sources of waterSources of water
Three main sources
◦ Precipitation
◦ melted water from ice and snow
◦ ground water from springs
Each of these contribute to the flow of
water on land surface called Runoff.

6. RillsRills
For short distance runoff may occur in
sheets [as sheet wash ]
Or un concentrated flow
Or it may from tiny channels
called Rills .
Tributaries are smaller
streams that feed into a larger one.

7. Stream SystemStream System
three major sub systems
◦ Catchments system
◦ Transport system
◦ Depositional or dispersal system
Drainage basin are surface areas that feed
runoff into a stream and exist for every
channel.

8. Inter fluveInter fluve
From Latin , inter----between,
fluvius----river
Higher land between two tributary valleys
of a drainage basin is referred as an
interfluves.
An imaginary line that separates two
drainage basins called Divide.

9. InfiltrationInfiltration
Process of water seeping into surface is
called Infiltration.
Ability of a ground surface to hold water is
called Infiltration Capacity.
In times of high flow streams over flow
their banks ,flat low lands on either sides
known as Flood plains.

10. Stream DischargeStream Discharge
 The volume of water flowing in a section
of channel in a given unit of time.
Stream Hydro graph is a record of
changes in discharge of stream over
time.
These hydro graphs indicate high and fast
water levels due to precipitation.

11. Hydro GraphHydro Graph
Discharge of a stream is recorded by a
gagging station in form of a hydro graph
curve.
Hydro graph curve plotted on a graph
which represents
◦ The rising limb
◦ Peak flow or flood crest
◦ The receding limb

12. Erosion by StreamErosion by Stream
Force of gravity affect stream water in
two ways
◦ Gravitational force causes water to flow down
slope.
◦ Gravity causes water to exert pressure on the
stream bed.

13. Causes of ErosionCauses of Erosion
When volume of flow in a stream increase
,the amount of energy to shape the land
also increases.
Ability of a stream to pick material
determined by the volume of water, its
depth, its friction with stream bed,
strength and size of rocks over which it
flows, and degree of stream turbulance.

14. Types of erosionTypes of erosion
There are three types of erosion.
◦ Hydraulic action
◦ Stream abrasion
◦ Solution [or dissolution]

15. Hydraulic ActionHydraulic Action
Hydraulic action occurs as
◦ As turbulent river currents wedge under rock
slabs on the bed
◦ Pound away at river banks
◦ Below water falls
Hydraulic action displaces loose particles from
stream bed or channel walls .
Sediments range in size from clay to silt ,sand ,
pebbles, cobbles .Gravel ,a general term for
rock particles larger than sand.

16. Stream AbrasionStream Abrasion
Rock particles bounce, scrape , and drag
along bottom and side of channels and
break off additional fragments is stream
abrasion.
This process make round depressions in
the rock of the stream bed is called
pot holes.

17. Solution or DissolutionSolution or Dissolution
Chemically dissolving the bed rock is a
process of solution.
Limited effect on rocks but may be
significant in limestone area.
Rock particles gradually reduce in size and
shape changes from angular to rounded is
called attrition .[ wear and tear on
sediments as they tumble and bounce
against one another and against stream
channel.

18. Stream TransportationStream Transportation
A greater proportion of sediments eroded
by surface run off .
The material transported by fluvial
processes are called Stream load.
Stream transport its load in several way
Solution
Suspension
Traction
Saltation

19. SolutionSolution
Some materials dissolved in water and
carried in solution like;
 lime , calcium, and ions of sodium and
other minerals.
Suspension are finest solid particles
which carried in suspension .
 Such particles remain suspended as long
as the force of upward turbulence is
stronger than downward settling tendency
of particles.

20. TractionTraction
“Sliding or rolling of particles along with
river bed” is traction.
Traction breaks down pebbles into
gravels, sand size.
Saltation is a combination of
suspension and traction.
When large particles hop and bounce
along the channel bottom is called
saltation.

21. Stream loadStream load
Three types of stream load
Suspended Load the material carried in
suspension. The largest portion of
sediments load is suspended load.
Bed Load the particles that roll or
saltate along the stream bed.
Dissolved Load is held in solution.

22. Stream transportStream transport
Two terms used to convey relation ship of
load and transportation
Stream Capacity refers how much load
a stream can carry.
Stream Competence is determined by
the diameter of the largest particles it
can transport as bed load.
Both increase in response of velocity,
discharge, and gradient increase.

23. Stream DepositionStream Deposition
A reduction in velocity and discharge will
cause a stream to reduce its load through
deposition.
Aggradations [deposition] occurs where
velocity is slow such as inside of bends in
channels, on floods plains, at river mouths
[deltas] ,and where stream gradient
abruptly flattens.
Alluvium is a general name of fluvial
deposits .

24. Land Forms made by StreamsLand Forms made by Streams
As the study of river course from its
headwaters to its mouth , three stages
are to be observed;
◦ Upper
◦ Middle
◦ Lower
Erosion tends to be significant in upper
stage, while deposition in lower course .

25. Features of upper courseFeatures of upper course
Steep sided valleys , a gorge, a ravine
created by erosion when stream channel
in the bottom of valley cuts deeply into
the land.
Steep sided valleys encourage mass
movement of rock material directly into
the flowing stream.
Many streams spills from lake to lake in
upper course .

26. Features of upper courseFeatures of upper course
V shaped valleys
valleys dominated by down cutting
activity of the streams , called v shaped
valleys because of their shape.

27. Features of middle courseFeatures of middle course
When a stream reduces its gradient ,
smoothed out its channel bed and begins
to approach its base level , vertical erosion
becomes less significant and lateral
erosion of channel sides assumes a more
important role.
It produces a narrow flood plain along the
banks.
Vertical erosion is minimized because the
stream is flowing over a gentle gradient

28. Features of Middles FeaturesFeatures of Middles Features
Vertical erosion become less significant and
lateral erosion assumes more important role.
Produces a valley floor with a smoother
stream gradient.
Produces a narrow flood plain along the
banks.
Verticals erosion is minimized.
River valley contains a floodplain but
maintain definite valley walls.
The stream course is meandering , loops
oxbow lakes ,and flood plains.

29. Features of lower courseFeatures of lower course
Dominated by depositional land forms.
Sediment – laden water deposits alluvium
on valley floor called alluvial plains.
Oxbow lakes
Natural leaves

30. Base LevelBase Level
The level below which a stream can not
erode its bed , is base level.
Three types of base level.
◦ Absolute base level
◦ Local base level
◦ Temporary base level

31. Absolute base levelAbsolute base level
When the capacity to erode ends, near
the ocean, is absolute level
Stream slows down
Deposits its sedimentary load
Erosion is terminated

32. Local base levelLocal base level
A stream that flows into a lake does not
relate the global sea level, the lake
becomes local base level.
Some times a stream erodes downward,
reaches a resistant rock barrier, that
keeps the river from developing a smooth
profile.
It creates a temporary base level.