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.

Rivers

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Distance from sea in Kms.

Source.

Upland stream.

Lowland river.

Mouth.

Gradient/slope decreasing

Velocity/flow increasing

Cumecs/discharge increasing

Energy increases

Upper course

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