Rivers. Long Profile Height above sea level in meters.0 50 100 150 200 250 35 30 25 20 15 10 5 0 Distance from sea in Kms. Source. Upland stream. Lowland.
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Rivers
Long ProfileH
eig
ht
abo
ve s
ea l
evel
in
m
eter
s.
0 5
0 1
00
150
200
25
0
35 30 25 20 15 10 5 0
Distance from sea in Kms.
Source.
Upland stream.
Lowland river.
Mouth.
Gradient/slope decreasing
Velocity/flow increasing
Cumecs/discharge increasing
Energy increases
Erosion Processes
• is when the river is loaded with material in suspension and scours away at the river banks. (Sandpaper effect)
• is the shear force of the river impacting on the sides of the river banks.
• is substances carried in solution such as acids. They dissolve rocks away over long periods of time.
• is when bed load collides into each other with the current flow and breaks down into smaller particles.
Abrasion (Corrasion)Abrasion (Corrasion) - - Hydraulic ActionHydraulic Action --
CorrosionCorrosion - -
AttritionAttrition --
Waterfall formationLook at the diagram, How is a waterfall formed?
High Force Waterfall R. Tees
Middle course, R. TeesMiddle course, R. TeesHOW DOES THIS DIFFER FROM THE UPPER SECTION?HOW DOES THIS DIFFER FROM THE UPPER SECTION?
Middle course, R. Tees
Valley opens out, more gentle slopes, wider valley bottom
First signs of meanders
River channel wider, deeper, greater velocity and discharge
WHAT DO YOU THINK THE ARROWS POINT TO?WHAT DO YOU THINK THE ARROWS POINT TO?
Meandering Rivers
WHAT IS A MEANDER?
Formation of Meanders
Point bar deposits
1
23
4
5
Match the feature/process to the correct definition. Add the number of the arrow alongside each feature / process.
Deep water A gently sloping area of land on the inside of a meander
Slip off slope Formed on the outside bend of the meander due to erosion.
River cliff Because of the gentle slope, there is a lot of frictional drag and so therefore the river flows at this speed
Fastest flow Maximum depth of the channel. (Note the asymmetrical cross-profile)
Slowest flow There is little frictional drag from the bed and bank at this point and so the river can flow at this speed.
Point Bar Deposits
Point bar deposits grows laterally through time
Meander, R. Lavant, Chichester
Meander, R. Lavant, Chichester
Floodplain
Point bar deposits on the inner meander bend where there is low energy
River Cliff Slip-Off Slope
WHAT DO THE ARROWS POINT TO?WHAT DO THE ARROWS POINT TO?WHICH WAY IS THIS
MEANDER MOVING?WHICH WAY IS THIS MEANDER MOVING?
Cut bank erosion (River Cliff)
Point bar deposits }Meander
loop
WHERE IS EROSION TAKING PLACE?WHERE IS EROSION TAKING PLACE?
WHERE IS DEPOSTION TAKING PLACE?WHERE IS DEPOSTION TAKING PLACE?
A
B
C
D
E
F
Meander on the R. Colorado
WHY IS DEPOSITION OCCURING HERE?WHY IS DEPOSITION OCCURING HERE?
How did these
meanders form?
REVISION: What River features do you get here?
Migrating meanders, R. Gongola, Nigeria
WHY ARE THEY MIGRATING?WHY ARE THEY MIGRATING?
What happens to the river when it moves to the middles course
• Gradient becomes less steep• River continues to erode vertically but
LATERAL erosion now occurs in MEANDERS
• What is MEANDER MIGRATION ?• Name three effects it have on the valley?• What factors effect how much load is
being carried?
Key words - Transportation.
• Traction – where large rocks and boulders are rolled along the river bed.
• 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.
Traction
Heavy rocks and boulders are rolled along the river bed. Happens most in times of flood, when the current
is strongest.
Saltation.
Small stones and pebbles are ‘bounced’ along the river
bed. Saltation can take place when the river flow is
less than that needed for ‘Traction’ to take place.
Suspension
Very small particles of sand or clay that are ‘suspended’ in the
water. These particles will ‘settle’ if kept in a jar of water overnight
and the water will look clear.
Solution.
Takes place when material is dissolved in the water, it is invisible and does not colour the
water. Occurs often in limestone landscapes where the water if very acidic. Some
pollutants like weedkiller are also held in solution in the water
Methods of transport
Copy this picture into your books and add the title above and labels for each type of transport
Traction Saltation Suspension Solution
Shows the rate of flow needed
Lower Course: Severn Valley
Lower Severn Valley
Well developed meanders with bars in the channel indicating high sediment load
Very gentle valley side gradients
HOW DOES IT DIFFER FROM THE MIDDLE COURSE?
Very wide floodplain
Flood Plains
The entire floodplain can become covered with water during floods.
HOW DO YOU THINK THE TERRACES WERE FORMED?
Ox Bow Lake FormationLOOK AT THE DIAGRAM & EXPLAIN THERE FORMATIONLOOK AT THE DIAGRAM & EXPLAIN THERE FORMATION
Formation of an Oxbow
Ox Bow lake on Mississippi
Levee formation
LeveesWHAT DO YOU THING HUMANS MIGHT HAVE DONE TO THIS LEVEE?WHAT DO YOU THING HUMANS MIGHT HAVE DONE TO THIS LEVEE?
Delta Formation
WHAT IS A DELTA?WHAT IS A DELTA?
DEPOSITON OF MATERIAL BY THE RIVER WHEN IT ENTERS THE SEADEPOSITON OF MATERIAL BY THE RIVER WHEN IT ENTERS THE SEA
WHY DOES IT DROP ITS SEDIMENTWHY DOES IT DROP ITS SEDIMENT
Mississippi Delta from Space
MISSISSIPPI
The Nile Delta from space
River NileRiver Nile
Estuary Formation
The Lower Course of a river valley has been DROWNED by a rise in sea level or a fall in the land level.
HOW DOES THIS DIFFER FROM A DELTA?HOW DOES THIS DIFFER FROM A DELTA?
RAISED VALLEY SIDESRAISED VALLEY SIDES
USING YOUR ATLASFIND AN ESTUARY (LOOK AT THE RIVER THAMES)
USING YOUR ATLASFIND AN ESTUARY (LOOK AT THE RIVER THAMES)
USING YOU ATLASLOCATE THE RHONE DELTA
USING YOU ATLASLOCATE THE RHONE DELTA
The Rhone Delta
The Rhone Delta S. FranceLook at p39 and identify the KEY FEATURES CAN YOU SEE IN THE SATELLITE PHOTO?
Look at p39 and identify the KEY FEATURES CAN YOU SEE IN THE SATELLITE PHOTO?
The Rhone Delta
WHY HAS A DELTA FORMED HERE? LOOK AT P 39 WHY HAS A DELTA FORMED HERE? LOOK AT P 39
Summary of valley characteristics
Upper Interlocking spurs “V” shaped valley Waterfall Gorge
Middle Wider valley Gentler valley sides
Meanders
Lower Widest part of valley
Floodplain Terraces Ox Bow & Levees Delta, Estuary
Lower Course: Severn Valley
Lower Severn Valley
Well developed meanders with bars in the channel indicating high sediment load
Very gentle valley side gradients
HOW DOES IT DIFFER FROM THE MIDDLE COURSE?
Very wide floodplain
Flood Plains
The entire floodplain can become covered with water during floods.
HOW DO YOU THINK THE TERRACES WERE FORMED?
Ox Bow Lake FormationLOOK AT THE DIAGRAM & EXPLAIN THERE FORMATIONLOOK AT THE DIAGRAM & EXPLAIN THERE FORMATION
Formation of an Oxbow
Ox Bow lake on Mississippi
Levee formation
LeveesWHAT DO YOU THING HUMANS MIGHT HAVE DONE TO THIS LEVEE?WHAT DO YOU THING HUMANS MIGHT HAVE DONE TO THIS LEVEE?
Delta Formation
WHAT IS A DELTA?WHAT IS A DELTA?
DEPOSITON OF MATERIAL BY THE RIVER WHEN IT ENTERS THE SEADEPOSITON OF MATERIAL BY THE RIVER WHEN IT ENTERS THE SEA
WHY DOES IT DROP ITS SEDIMENTWHY DOES IT DROP ITS SEDIMENT
Mississippi Delta from Space
MISSISSIPPI
The Nile Delta from space
River NileRiver Nile
Estuary Formation
The Lower Course of a river valley has been DROWNED by a rise in sea level or a fall in the land level.
HOW DOES THIS DIFFER FROM A DELTA?HOW DOES THIS DIFFER FROM A DELTA?
RAISED VALLEY SIDESRAISED VALLEY SIDES
USING YOUR ATLASFIND AN ESTUARY (LOOK AT THE RIVER THAMES)
USING YOUR ATLASFIND AN ESTUARY (LOOK AT THE RIVER THAMES)
USING YOU ATLASLOCATE THE RHONE DELTA
USING YOU ATLASLOCATE THE RHONE DELTA
The Rhone Delta
The Rhone Delta S. FranceLook at p39 and identify the KEY FEATURES CAN YOU SEE IN THE SATELLITE PHOTO?
Look at p39 and identify the KEY FEATURES CAN YOU SEE IN THE SATELLITE PHOTO?
The Rhone Delta
WHY HAS A DELTA FORMED HERE? LOOK AT P 39 WHY HAS A DELTA FORMED HERE? LOOK AT P 39
Summary of valley characteristics
Upper Interlocking spurs “V” shaped valley Waterfall Gorge
Middle Wider valley Gentler valley sides
Meanders
Lower Widest part of valley
Floodplain Terraces Ox Bow & Levees Delta, Estuary
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