The Changes downstreamThe Changes downstream

in a river valleyin a river valleyRIVER RIVER STUDIESSTUDIES

The Hydrologic CycleThe Hydrologic Cycle

Infiltration = Groundwater SystemInfiltration = Groundwater System

Runoff = Surface Water SystemRunoff = Surface Water System

Satellite view of river Satellite view of river drainage, Middle Eastdrainage, Middle East

What is this features?

Upper valley Upper valley characteristicscharacteristics

Upper valley Upper valley characteristicscharacteristics

Upper valley Upper valley characteristicscharacteristics

“V”shape valley, vertical erosion dominant

Upper valley Upper valley characteristicscharacteristics

“V”shape valley, vertical erosion dominant

Interlocking spurs

Upper valley Upper valley characteristicscharacteristics

“V”shape valley, vertical erosion dominant

Interlocking spurs

Slumping and landslides - very active hill slopes

Upper valley Upper valley characteristicscharacteristics

“V”shape valley, vertical erosion dominant

Interlocking spurs

Slumping and landslides - very active hill slopes

Narrow, shallow channel, low velocity and discharge

Upper valley Upper valley characteristicscharacteristics

“V”shape valley, vertical erosion dominant

Interlocking spurs

Slumping and landslides - very active hill slopes

Narrow, shallow channel, low velocity and discharge

Large bed load derived from upstream and from valley sides

Interlocking spurs, Interlocking spurs, Robinson, Lake DistrictRobinson, Lake District

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

River load in upper River load in upper coursecourse

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

Why are they rounded?

Rapids in the Upper Tees Rapids in the Upper Tees ValleyValley WHAT IS A RAPID?WHAT IS A RAPID?

High Force waterfall, R. High Force waterfall, R. TeesTees

WHAT IS A WATERFALL?

High Force waterfall, R. High Force waterfall, R. TeesTees

Plunge pool

What is this feature called?

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

HOW IS A GORGE FORMED?

HOW IS A GORGE FORMED?

Waterfall formationWaterfall formationLook at the diagram, How is a waterfall formed?

High Force Waterfall R. High Force Waterfall R. TeesTees

Close-up of potholesClose-up of potholesHow are these formed?

Potholes, human scale!!Potholes, human scale!!

Erosion ProcessesErosion Processes

is when the river is loaded with material in suspension is when the river is loaded with material in suspension and scours away at the river banks. (Sandpaper and scours away at the river banks. (Sandpaper effect)effect)

is the shear force of the river impacting on the sides of is the shear force of the river impacting on the sides of the river banks.the river banks.

is substances carried in solution such as acids. They is substances carried in solution such as acids. They dissolve rocks away over long periods of time.dissolve rocks away over long periods of time.

is when bed load collides into each other with the is when bed load collides into each other with the current flow and breaks down into smaller particles.current flow and breaks down into smaller particles.

Abrasion (Corrasion)Abrasion (Corrasion) - - Hydraulic ActionHydraulic Action --

CorrosionCorrosion - -

AttritionAttrition --

Middle course, R. TeesMiddle course, R. TeesMiddle course, R. TeesMiddle course, R. TeesHOW DOES THIS DIFFER FROM THE UPPER SECTION?HOW DOES THIS DIFFER FROM THE UPPER SECTION?

Middle course, R. TeesMiddle 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 RiversMeandering Rivers

WHAT IS A MEANDER?

Formation of MeandersFormation of Meanders

Point bar deposits

Point Bar DepositsPoint Bar Deposits

Point bar deposits grows laterally through time

Meander, R. Lavant, Meander, R. Lavant, ChichesterChichester

Meander, R. Lavant, Meander, R. Lavant, ChichesterChichester

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. Meander on the R. ColoradoColorado

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. Migrating meanders, R. Gongola, NigeriaGongola, Nigeria

WHY ARE THEY MIGRATING?WHY ARE THEY MIGRATING?

What happens to the river What happens to the river when it moves to the when it moves to the middles coursemiddles course

Gradient becomes less steepGradient becomes less steep River continues to erode vertically but River continues to erode vertically but

LATERAL erosion now occurs in LATERAL erosion now occurs in MEANDERSMEANDERS

What is MEANDER MIGRATION ?What is MEANDER MIGRATION ? Name three effects it have on the valley?Name three effects it have on the valley? What factors effect how much load is What factors effect how much load is

being carried?being carried?

TransportationTransportation

What are the four methods of transportation?What are the four methods of transportation? TractionTraction - is when large particles roll along the river - is when large particles roll along the river

bedbed

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

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

SolutionSolution - is when dissolved material is carried. - is when dissolved material is carried.

Lower Course: Severn Lower Course: Severn ValleyValley

Lower Severn ValleyLower 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 PlainsFlood Plains

The entire floodplain can become covered with water during floods.

HOW DO YOU THINK THE TERRACES WERE FORMED?

Ox Bow Lake FormationOx Bow Lake FormationLOOK AT THE DIAGRAM & EXPLAIN THERE FORMATIONLOOK AT THE DIAGRAM & EXPLAIN THERE FORMATION

Formation of an Oxbow

Ox Bow lake on Ox Bow lake on MississippiMississippi

LevLevee formationee formation

LeveesLeveesWHAT 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 Mississippi Delta from Space Space

MISSISSIPPI

The Nile Delta from spaceThe Nile Delta from space

River NileRiver Nile

Estuary FormationEstuary 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 DeltaThe Rhone Delta

The Rhone Delta S. The Rhone Delta S. FranceFranceLook 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 DeltaThe 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 Summary of valley characteristicscharacteristics

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

The River TeesThe River Tees

TRY AND FIND THE RIVER TEESIN YOUR ATLAS

HINT LOOK AT THE MAP

TRY AND FIND THE RIVER TEESIN YOUR ATLAS

HINT LOOK AT THE MAP

Land Use in Drainage Basin Land Use in Drainage Basin of River Teesof River Tees

WHAT IS THE AREA IN EACH BOX?WHAT IS THE AREA IN EACH BOX?

Upper TeesUpper Tees

WHAT HUMAN INFLUENCES EXIST IN THE MAPS?WHAT HUMAN INFLUENCES EXIST IN THE MAPS?

COW GREEN RESERVOIRCOW GREEN RESERVOIR

The Upper Tees Cronkley The Upper Tees Cronkley ScarScar

WHAT LAND USES CAN YOU SEE IN THE PHOTO?WHAT LAND USES CAN YOU SEE IN THE PHOTO?

WHAT ARE THE KEY GEOGRAPHCIAL FEATURES YOU CAN SEE IN THE PHOTOGRAPHWHAT ARE THE KEY GEOGRAPHCIAL FEATURES YOU CAN SEE IN THE PHOTOGRAPH

MOORLANDMOORLAND

STEEP VALLEY

SLOPE DEBRISSLOPE DEBRIS

TURBULENT RIVER

CHANNEL

TURBULENT RIVER

CHANNEL

Upper TeesUpper Tees

WHAT IS THE NAME OF THE WATERFALL?WHAT IS THE NAME OF THE WATERFALL?

The Lower Course TeesThe Lower Course TeesThe Lower Course TeesThe Lower Course Tees

HOW HAS THE RIVER AND LAND USE CHANGED?HOW HAS THE RIVER AND LAND USE CHANGED?

FLAT VALLEY FLOORFLAT VALLEY FLOOR

WIDE MEANDERSWIDE MEANDERS

URBAN SETTLEMENTURBAN SETTLEMENT

WHAT LAND USE CAN YOU SEE IN THE PHOTOGRAPH?WHAT LAND USE CAN YOU SEE IN THE PHOTOGRAPH?

The Lower TeesThe Lower TeesTEESMOUTH ESTUARYTEESMOUTH ESTUARY

The River meets the SeaThe River meets the Sea

LOOK AT P42WHAT DO YOU THINK THE PHOTOS SHOW?

LOOK AT P42WHAT DO YOU THINK THE PHOTOS SHOW?

WHAT IS THE FUNCTIONOF THE BARRAGE?WHAT IS THE FUNCTIONOF THE BARRAGE?

River ManagementRiver Management

Formation of the Formation of the Mississippi River DeltaMississippi River Delta

Early delta

More recent delta sediments Modern

delta

Causes of FloodsCauses of Floods

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

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

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

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

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

Flood Control and Flood Control and ManagementManagement

There are a number of ways managing floods:There are a number of ways managing floods: 1. 1. Afforestation Afforestation - planting trees increases interception rates and reduces - planting trees increases interception rates and reduces

surface runoff.surface runoff. 2. 2. Dams and ReservoirsDams and Reservoirs - these hold back and regulate the flow of river - these hold back and regulate the flow of river

water. Can be used as fresh water supply and generation of HEP.water. Can be used as fresh water supply and generation of HEP. 3. 3. Diversion ChannelsDiversion Channels - overflow channels which take surplus water out of a - overflow channels which take surplus water out of a

river in times of flood.river in times of flood. 4. 4. Channel Straitening and DredgingChannel Straitening and Dredging - smoothens the channel to increase - smoothens the channel to increase

the speed (velocity) of the river and get water out of the drainage basin as the speed (velocity) of the river and get water out of the drainage basin as quickly as possible.quickly as possible.

5. 5. Artificial LeveesArtificial Levees - makes river banks higher therefore holding more water. - makes river banks higher therefore holding more water. 66. Culverts. Culverts - semi circular, smooth channels increase velocity and gets - semi circular, smooth channels increase velocity and gets

water away from urban areas as quickly as possible.water away from urban areas as quickly as possible. 7. 7. Revetments and Channel WallsRevetments and Channel Walls - strengthen river banks from erosion. - strengthen river banks from erosion.