Mr. Dhawale Ganesh Madhukar
Hydrologic cycle - the movement and interchange of water between the sea, air, and land
• Solar radiation provides energy
• Rain or snow
– Hydrologic cycle – the movement and interchange of water between the sea, air, and land.
• Evaporation from plants
• Water flowing over land surface
• Water soaking into the ground
Click to view animation
• Stream – a body of running water that is confined in a channel and moves
downhill under the influence of gravity.
Water velocity is the key factor in stream erosion, transportation, and deposition.
• Stream velocity – the distance water travels in a stream per unit time.
– Expressed in ft./sec.
– The stream reaches its maximum velocity near the middle of the channel.
Types of River
What processes occur in a river?
There are 3 processes taking place in
(The wearing away of the land)
Transportation (The movement of
Deposition (The laying down of eroded
There are also two other processes that shape the river valley. These are
weathering and mass movement.
Ganga river- Length :-2,525 km Discharge( Farakka Barrage ) - average 12,500 m3/s
Shaping the river valley.
There are also two other processes that
shape the river valley. These are weathering
and mass movement.
Weathering = the breakdown of rock material.
Mass movement = the movement downslope of
broken down rock material due to gravity.
Abrasion (Corrasion) is when the river is loaded with material in suspension
and scours away at the river banks. (Sandpaper effect)
Hydraulic Action is the shear force of the river impacting on the sides of
the river banks.
Corrosion is substances carried in solution such as acids. They dissolve
rocks away over long periods of time.
Attrition is when bed load collides into each other with the current flow and
breaks down into smaller particles.
Key words - Transportation.
• Traction – where large rocks and boulders are
rolled along the river bed. Happens most in times of
flood, when the current is strongest.
• Saltation – where smaller stones are bounced along
the river bed in a leap frogging motion
• Suspension – where very small grains of sand or silt
are carried along with the water
• Solution – where some material is dissolved (like
sugar in a cup of tea) and is carried downstream.
Occurs often in limestone landscapes where the
water if very acidic.
Methods of transportation.
Shows the rate of flow needed
What is a drainage basin?
Where the river
flows into the
sea, or sometimes
A river which joins a larger river.
from another- a
ridge of high
The point at which two rivers join.
The area from
drains into a
The upland area
where the river
0 50 100 150 200 250
Height above sea level in meters.
Distance from sea in Kms.
Valley & Channel Cross-Sections
Upper Course Middle Course
The Work of Rivers
The work of a river depends on its energy
Energy a function of
a. Volume of water
b. Speed of water flow (dependent on
c. Types of rocks
The Upper Course of a river
•To know and
landforms in a river’s
•To understand the
operate in a river’s
Upper valley characteristics
landslides very active
Large bed load
Upper valley characteristics -River load
Material that is
a river is called its
River load in upper course
Why are they rounded?
Boulders are large and semi-rounded,
due to attrition within the load and
abrasion with the stream bed and
The Middle and Lower Course of a River
•To understand the main processes that operate
in the middle and lower course of a river.
•To understand how meanders and oxbow lakes
Processes operating in the middle course
of a river
Erosion is still an important process.
The river is now flowing over flatter land and so the
dominant direction of erosion is lateral (from side to side).
The river has a greater discharge and so has more energy to
transport material. Material that is transported by a river is
called its load.
Deposition is also an important process and occurs when the
velocity of the river decreases or if the discharge falls due
to a dry spell of weather.
The Lower Course of a River
To be able to describe and explain the formation of a flood plain,
levees, delta .
• A flood plain is the wide, flat area of land on
either side of the river in its middle and
• Levees are natural embankments of silt along
the banks of a river, which are often several
metres higher than the flood plain.
Floodplain & Levee formation
Floodplains and leveés are formed by deposition in times of river flood.
The river’s load is composed of different sized particles.
When a river floods, the river water overflows the banks of the river and
immediately slows down due to friction.
This drops the larger particles first, building up a raised river bank called a
The sands, silts and clays are similarly sorted with the sands being deposited
next, then the silts and finally the lightest clays. This builds up the floodplain.
Deltas form at the mouths of many of the
world’s larger rivers, e.g the Nile (Egypt),
the Ganges (Bangladesh), the Mississippi
A delta is a flat area of sand and silt built into the
sea. It is formed by deposition.
1. When a river enters a sea or lake carrying large
volumes of fine material, the velocity slows and
causes the load to be deposited in layers.
2. Over time, the deposited material blocks
channels and forms small islands separated by
river channels called distributaries.
Deltas – a body of sediment deposited at the mouth of a river when the river’s velocity decreases.
– A stream flowing into quiet water usually builds a delta.
– The surface is usually marked by distributaries – small, shifting channels that carry water away
from the main river channel and distributes it over the surface of the delta.
Human Aspects of Rivers :1.
Chief highway of commerce and transport
2. Fertile soil
3. Generation of hydro-electric power
4. Construct dams (for irrigation, power generation,
control on flood)
5. Fresh water – fishing, domestic consumption,
sewerage, and industrial purpose
6. Political boundaries
Dam Construction- (Disturbing present ecosystem),
Festival (Ganesh Utsav),
Ganga Action Plan
Launched in April 1986 in order to reduce the pollution load on the river.
Spending Rs 901.71 Crores.
Withdrawn on 31 March 2000.
Phase-II of the program was approved in stages from 1993 onwards, and included
the following tributaries of the Ganges: Yamuna, Gomti, Damodar and Mahananda.