WHAT CAN YOU REMEMBER?

landocean

4) _________

5) __________1) ________

2) _________

3) _________

6) ________

WHAT CAN YOU REMEMBER?

landocean

transpiration

surface runoffevaporation

condensation

precipitation

ground water

PHYSICAL LANDSCAPE

SINTRODUCING RIVERS

WHAT ARE WE GOING TO LEARN?

1.What is a drainage basin?

2.Why is a drainage basin like a kitchen sink?

3.What are the four processes of erosion in rivers?

4.What are the four processes of transportation in rivers?

THE DRAINAGE BASIN

A drainage basin is an

area of land that is

drained by a river and its tributaries.

Dyfi

DRAINAGE BASIN

THE DRAINAGE BASIN

Nature’s ‘kitchen sink’

The higher

land that forms the edge, or boundary

, of a drainage basin is

called the watershe

d.WATERSHED

THE DRAINAGE BASIN

All the rain that

falls within a drainage

basin flows into a single

river channel

that flows to the sea

(or lake).Drainage

basins act like nature’s

kitchen sinks.

River Basin Features

• Watershed the area of high land forming the edge of a river basin.

• Source where a river begins.

• Mouth where a river meets the sea.

• Confluence the point at which two rivers meet.

• Tributary a small river or stream that joins a larger river.

• Channel this is where the river flows.

• Drainage Basin this is the area of land drained by a river and its tributaries.

DRAINAGE BASIN TERMSSOURC

E

CONFLUENCE

TRIBUTARY

CHANNEL

MOUTH

PHYSICAL LANDSCAPE

STHE RIVER COURSE

UPPER COURSE

MIDDLE COURSE

LOWER COURSE

THE RIVER COURSE

Rivers play a big role in shaping our landscape.

They are able to do this because they have energy.

This means that they can do work.

The work they do is erosion and transportation.

When they run out of energy they have to stop doing work, so they drop what they are carrying. This is called deposition.

RIVER PROCESSES

EROSION PROCESSES

Erosion is the wearing away of the river bed, river

There are four processes of river erosion:•attrition •corrasion •corrosion •hydraulic action

TRANSPORTATION PROCESSES

There are four processes of transportation:

•traction

•saltation

•suspension

•solution

TRANSPORTATION PROCESSES

Saltation Traction

SuspensionSolution

RIVER EROSION

THE SOURCE

• The source is the start or beginning of a river.

• The source of a river is usually found in the hills or mountains.

SPRINGS

rainWater can sink through gaps in

the rocksPermeable

rock ie Limestone

Rocks are saturated

Impermeable rock ie Clay Spring

Underground water

emerges where the rock type changes

UPPER COURSE

MIDDLE COURSE

LOWER COURSE

THE RIVER COURSE

UPPER COURSE CHARACTERISTICSsteep channel

gradientnarrow valley floor

narrow, shallow channel

steep valley sides

Upper Course Characteristi

cs

large, angular stones

and boulders

UPPER COURSE CHARACTERISTICS

turbulent river flow at a section of rapids

Upper Course Landforms

a typical V-shaped valley

Key Features:

• V-shaped valley

A steep sided and narrow valley that is formed due to vertical erosion. The load of the river cuts downwards and deepens the bed of the river.

Upper Course Landforms

a typical V-shaped valley

Upper Course Landforms

interlocking spurs

interlocking spurs

Upper Course Landforms

interlocking spurs

interlocking spurs

Angel Falls, Venezuela

Hopetoun Falls, Australia

Victoria Falls, Zambia/Zimbabwe

Jog Falls, India

Niagara Falls, Canada/USA

PLUNGE POOLUNDERCUTTIN

G OF SOFT ROCK

OVERHANG

WATERFALL RETREATS . .UPSTREAM . .

Upper Course Landforms

interlocking spurs

interlocking spurs

• Rapids

A series of gentle breaks in the slope of a river bed due to different types of rock.

Hydro-electric power

River Model

UpperCourse

MiddleCourse

LowerCourse

The Middle The Middle CourseCourse

S3 S3 Rivers:Rivers:

• At the middle stage of the river At the middle stage of the river the valley sides become less steepthe valley sides become less steep

• The river is now wider and The river is now wider and deeperdeeper

• It does not flow at the same It does not flow at the same speed throughout its middle speed throughout its middle

course, some parts are course, some parts are slower, some are fasterslower, some are faster

Meander ( = bend in a river’s channel)

What do you notice about the bank of the river channel on the outside of the bend?

Which is the fastest side of a river?

Why do rivers meander (bend)?

1. Copy the diagram above and put the following labels in the correct place:

Deposition Fast flow of river Shallow water

River Cliff Lateral Erosion Slow flow of river Deeper water River beach (Slip-off slope)

2. Describe why one side of the river bend is different from the other.

The Lower The Lower CourseCourse

S3 S3 Rivers:Rivers:

• At its lower stagelower stage, the river is in a wide flat valley with gentle valley

sides

• The river is closest to its mouth

A

D

FB

C

E

Ox-bow Lakes

1. The river erodes the outside of the bend and deposits on the inside so its course is changing. This erosion narrows the neck of the meander.

2. Often during a flood the river will cut through the neck.

3. The river continues in the new bed and the meander is abandoned. New deposition seals off the ends and the cut-off becomes an ox-bow lake.

Ox-bow lake on Mississippi

Levee formation

Built-up levees

1. When a river with a

very low gradient

floods a lot of silt is

deposited on the river

banks and much less on

the flood plain.

2. Frequent flooding

continues this build up of silt. When the river is

flowing normally it deposits in

the river bed.

3. This raises the

river above the flood plain but,

usually the built up levées

protect the plain from flooding.