River features
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River features?. Are facial features the same thing for rivers?. River Features. Rivers are eroding, transporting and depositing constantly. The river can be divided into 3 sections – Upper Course at the Source, Middle Course and Lower Course at the Mouth of the river.

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River features

River features?

Are facial features the same thing for rivers?


River features1

River Features

  • Rivers are eroding, transporting and depositing constantly.

  • The river can be divided into 3 sections – Upper Course at the Source, Middle Course and Lower Course at the Mouth of the river.

  • The river displays different characteristics at each section.


River structure

River Structure


Upper valley characteristics

Upper valley characteristics

“V”shape valley, mostly vertical erosion

Narrow, shallow channel, low velocity and discharge

Interlocking spurs

Large rocksthat come from upstream and from valley sides


Interlocking spurs robinson lake district

Interlocking spurs, Robinson, Lake District

An upper course valley often has interlocking spurs, and steep valley sides


River load in upper course

River load in upper course

Why are they rounded?


River load in upper course1

River load in upper course

Why are they rounded?

Boulders are large and semi-rounded, due to attritionwithin the loadand abrasion with the stream bed and banks


Waterfall formation

Waterfall formation

Look at the diagram, How is a waterfall formed?


Upper course waterfalls gorges

Upper Course: Waterfalls & Gorges

Waterfall and Gorge 1

(OBLIQUE AERIAL VIEW)

EROSION TYPE: Vertical and Headward


High force waterfall r tees

High Force waterfall, R. Tees

Waterfall creates gorge as it recedes upstream by eroding the base and neck

Plunge pool


Upper course potholes

Upper Course: Potholes

Potholes

EROSION TYPE: Vertical

(by EDDY CURRENTS)

Boulders broken off by erosion that sit on the river bed create swirling eddy currents as the water flows past as the river is not strong enough yet to move the boulders by TRACTION. These eddies swirl the boulder round and erode a pothole in the river bed by ABRASION.


Potholes human scale

Potholes, human scale!!


Middle course r tees

Middle course, R. Tees

HOW DOES THIS DIFFER FROM THE UPPER SECTION?


Middle course r tees1

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


Meandering rivers

Meandering Rivers

WHAT IS A MEANDER?


Middle course meanders

Middle Course: Meanders

Meanders 1

(Aerial View)

Meanders are formed because the current swings to the outside of a bend and concentrates the erosion there. Deposition occurs on the inside of the bed where there is not enough energy to carry load.

EROSION TYPE: Lateral


Middle course meanders 2

Middle Course: Meanders 2

Meanders 2

(Profile View / Cross Section X - Y)

EROSION TYPE: Lateral

This cross section clearly shows the eddy current (near ’X’) formed by the velocity of the river being concentrated on the outside of the bend. These UNDERCUT the bank causing the formation of a RIVER CLIFF. On the inside (NEAR ‘Y’), a SLIP-OFF-SLOPE is formed where current is too slow to carry any load.


Meander r lavant chichester

Meander, R. Lavant, Chichester

WHICH WAY IS THIS MEANDER MOVING?

Floodplain

Slip-Off Slope

River Cliff

Pebble deposits on the inner meander bend where there is low energy


River features

WHERE IS EROSION TAKING PLACE?

River Cliff

F

A

E

B

Slip-off slope

}

Meander loop

C

D

WHERE IS DEPOSTION TAKING PLACE?


What happens to the river when it moves to the middle course

What happens to the river when it moves to the middle course

  • Gradient becomes less steep

  • River continues to erode vertically a bit but more LATERAL erosion now occurs in MEANDERS

  • The meanders MIGRATE. What do you think that means?

  • Name three effects it have on the valley.


Lower course severn valley

Lower Course: Severn Valley

HOW DOES IT DIFFER FROM THE MIDDLE COURSE?


Lower severn valley

Lower Severn Valley

Very wide floodplain

Well developed meanders with bars in the channel indicating high sediment load

Very gentle valley side gradients


Lower course ox bow lake

Lower Course: Ox-bow lake

Ox-Bow Lake 1

(Aerial View)

Ox-bow lakes are formed when two meander RIVER CLIFFS are being eroded towards each other. These will eventually meet, causing the river to then flow across the bottom of the diagram.

EROSION TYPE: Lateral


Lower course ox bow lake 2

Lower Course: Ox-bow lake 2

Ox-Bow Lake 2(Aerial View)


Ox bow lake on mississippi

Ox Bow lake on Mississippi


The nile delta from space

The Nile Delta from space

River Nile


Estuary formation

Estuary Formation

HOW DOES THIS DIFFER FROM A DELTA?

RAISED VALLEY SIDES


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