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RIVER STUDIES. The Changes downstream in a river valley. The Hydrologic Cycle. Infiltration = Groundwater System. Runoff = Surface Water System. Satellite view of river drainage, Middle East. What is this features?. Upper valley characteristics. Upper valley characteristics.

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River studies l.jpg

RIVER STUDIES

The Changes downstream

in a river valley


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The Hydrologic Cycle

  • Infiltration = Groundwater System

  • Runoff = Surface Water System





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Upper valley characteristics

“V”shape valley, vertical erosion dominant


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Upper valley characteristics

“V”shape valley, vertical erosion dominant

Interlocking spurs


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Upper valley characteristics

“V”shape valley, vertical erosion dominant

Interlocking spurs

Slumping and landslides - very active hill slopes


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Upper valley characteristics

“V”shape valley, vertical erosion dominant

Narrow, shallow channel, low velocity and discharge

Interlocking spurs

Slumping and landslides - very active hill slopes


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Upper valley characteristics

“V”shape valley, vertical erosion dominant

Narrow, shallow channel, low velocity and discharge

Interlocking spurs

Slumping and landslides - very active hill slopes

Large bed load derived from upstream and from valley sides


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Interlocking spurs, Robinson, Lake District

A typical upper course valley with interlocking spurs, steep valley sides and active slope processes


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River load in upper course

Why are they rounded?

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



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High Force waterfall, R. Tees

WHAT IS A WATERFALL?


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High Force waterfall, R. Tees

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

What is this feature called?

HOW IS A GORGE FORMED?

Plunge pool


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Waterfall formation

Look at the diagram, How is a waterfall formed?



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Close-up of potholes

How are these formed?



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Erosion Processes

Corrosion -

Attrition-

Abrasion (Corrasion) -

Hydraulic Action-

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.


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Middle course, R. Tees

HOW DOES THIS DIFFER FROM THE UPPER SECTION?


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Middle course, R. Tees

WHAT DO YOU THINK THE ARROWS POINT TO?

Valley opens out, more gentle slopes, wider valley bottom

First signs of meanders

River channel wider, deeper, greater velocity and discharge


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Meandering Rivers

WHAT IS A MEANDER?




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Point Bar Deposits

Point bar deposits grows laterally through time



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Meander, R. Lavant, Chichester

WHAT DO THE ARROWS POINT TO?

WHICH WAY IS THIS MEANDER MOVING?

Floodplain

Slip-Off Slope

River Cliff

Point bar deposits on the inner meander bend where there is low energy


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WHERE IS EROSION TAKING PLACE?

Cut bank erosion (River Cliff)

F

A

E

B

Point bar deposits

}

Meander loop

C

D

WHERE IS DEPOSTION TAKING PLACE?


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Meander on the R. Colorado

WHY IS DEPOSITION OCCURING HERE?





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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?


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Transportation course

  • What are the four methods of transportation?

  • Traction- is when large particles roll along the river bed

  • Saltation - is when smaller particles bounce and collide in a leapfrog manner across the river bed.

  • Suspension - is when the river holds even smaller particles and carries them in its current. This is when the river appears to be murky.

  • Solution - is when dissolved material is carried.



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Lower Severn Valley course

Very wide floodplain

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?


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Flood Plains course

HOW DO YOU THINK THE TERRACES WERE FORMED?

The entire floodplain can become covered with water during floods.


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Ox Bow Lake Formation course

LOOK AT THE DIAGRAM & EXPLAIN THERE FORMATION




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Lev courseee formation


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Levees course

WHAT DO YOU THING HUMANS MIGHT HAVE DONE TO THIS LEVEE?


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Delta Formation course

WHAT IS A DELTA?

DEPOSITON OF MATERIAL BY THE RIVER

WHEN IT ENTERS THE SEA

WHY DOES IT DROP ITS SEDIMENT



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The Nile Delta from space course

River Nile


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Estuary Formation course

HOW DOES THIS DIFFER FROM A DELTA?

The Lower Course of a river valley has been DROWNED by a rise in sea level or a fall in the land level.

RAISED VALLEY SIDES

USING YOUR ATLAS

FIND AN ESTUARY

(LOOK AT THE RIVER THAMES)


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The Rhone Delta course

USING YOU ATLAS

LOCATE THE RHONE

DELTA


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The Rhone Delta S. France course

Look at p39 and identify the

KEY FEATURES CAN YOU

SEE IN THE SATELLITE PHOTO?


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The Rhone Delta course

WHY HAS A DELTA

FORMED HERE? LOOK AT P 39



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The River Tees course

TRY AND FIND THE RIVER TEES

IN YOUR ATLAS

HINT LOOK AT THE MAP


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Land Use in Drainage Basin of River Tees course

WHAT IS THE AREA IN EACH BOX?


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Upper Tees course

COW GREEN RESERVOIR

WHAT HUMAN INFLUENCES EXIST IN THE MAPS?


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The Upper Tees Cronkley Scar course

WHAT ARE THE KEY GEOGRAPHCIAL FEATURES

YOU CAN SEE IN THE PHOTOGRAPH

MOORLAND

STEEP VALLEY

TURBULENT RIVER

CHANNEL

SLOPE DEBRIS

WHAT LAND USES CAN YOU SEE IN THE PHOTO?


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Upper Tees course

WHAT IS THE NAME OF THE WATERFALL?


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The Lower Course Tees course

FLAT VALLEY FLOOR

URBAN

SETTLEMENT

WIDE MEANDERS

HOW HAS THE RIVER AND

LAND USE CHANGED?


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The Lower Tees course

TEESMOUTH ESTUARY

WHAT LAND USE CAN YOU SEE IN THE PHOTOGRAPH?



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River Management course

WHAT IS THE FUNCTIONOF THE BARRAGE?

LOOK AT P42

WHAT DO YOU THINK

THE PHOTOS SHOW?


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Formation of the Mississippi River Delta course

More recent delta sediments

Modern delta

Earlydelta


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Causes of Floods course

A Flood can occur when a river exceeds its bank full stage and water will subsequently inundate the adjacent surrounding area.

Heavy rainfall - long periods of heavy rainfall will lead to an increase in surface runoff and increase in river level.

Snow melt and heavy rainfall - water in storage may be freed by Spring melts increasing surface runoff.

Deforestation - cutting down of trees leads to a reduction in interception rates and an increase in surface runoff. This may also lead to rapid erosion rates due to a lack of stability in the soil subsurface.

Urbanisation - tarmac and concrete surfaces are impermeable and lead to an increase in surface runoff.


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Flood Control and Management course

There are a number of ways managing floods:

1. Afforestation - planting trees increases interception rates and reduces surface runoff.

2. Dams and Reservoirs - these hold back and regulate the flow of river water. Can be used as fresh water supply and generation of HEP.

3. Diversion Channels - overflow channels which take surplus water out of a river in times of flood.

4. Channel Straitening and Dredging - smoothens the channel to increase the speed (velocity) of the river and get water out of the drainage basin as quickly as possible.

5. Artificial Levees - makes river banks higher therefore holding more water.

6. Culverts - semi circular, smooth channels increase velocity and gets water away from urban areas as quickly as possible.

7. Revetments and Channel Walls - strengthen river banks from erosion.


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