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RIVER STUDIES. Channel processes and features Valley slope processes and landforms. Satellite view of river drainage, Middle East. Microscale drainage basin. Upper valley characteristics. Upper valley characteristics. Upper valley characteristics.

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river studies

RIVER STUDIES

Channel processes and features

Valley slope processes and landforms

upper valley characteristics6
Upper valley characteristics

“V”shape valley, vertical erosion dominant

upper valley characteristics7
Upper valley characteristics

“V”shape valley, vertical erosion dominant

Interlocking spurs

upper valley characteristics8
Upper valley characteristics

“V”shape valley, vertical erosion dominant

Interlocking spurs

Slumping and landslides - very active hillslopes

upper valley characteristics9
Upper valley characteristics

“V”shape valley, vertical erosion dominant

Terracettes formed by soil creep

Interlocking spurs

Slumping and landslides - very active hillslopes

upper valley characteristics10
Upper valley characteristics

“V”shape valley, vertical erosion dominant

Terracettes formed by soil creep

Narrow, shallow channel, low velocity and discharge

Interlocking spurs

Slumping and landslides - very active hillslopes

upper valley characteristics11
Upper valley characteristics

“V”shape valley, vertical erosion dominant

Terracettes formed by soil creep

Narrow, shallow channel, low velocity and discharge

Interlocking spurs

Slumping and landslides - very active hillslopes

Large bedload derived from upstream and from valley sides

interlocking spurs robinson lake district
Interlocking spurs, Robinson, Lake District

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

choked runnel n pennines
Choked runnel, N. Pennines

Ephemeral stream or runnel - water present only during high rainfall events

choked runnel n pennines14
Choked runnel, N. Pennines

Ephemeral stream or runnel - water present only during high rainfall events

Debris brought downslope towards channel - dropped when water disappears after storm

choked runnel n pennines15
Choked runnel, N. Pennines

Vertical erosion creating steep, bare slopes vulnerable to further erosion - an example of positive feedback in a slope system

Ephemeral stream or runnel- water present only during high rainfall events

Debris brought downslope towards channel - dropped when water disappears after storm

river load in upper course
River load in upper course

Load is dumped in summer due to the low discharge unable to carry the c________and c__________of load at higher flow levels

river load in upper course17
River load in upper course

Load is dumped in summer due to the low discharge unable to carry the capacity and competence of load at higher flow levels

river load in upper course18
River load in upper course

Load is dumped in summer due to the low discharge unable to carry the capacity and competence of load at higher flow levels

river load in upper course19
River load in upper course

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

Load is dumped in summer due to the low discharge unable to carry the capacity and competence of load at higher flow levels

rapids in the upper tees valley21
Rapids in the Upper Tees Valley

Rapids are mini-waterfalls

Protruding bands of more resistant strata create steps over which rapids fall - the river bed is ungraded

rapids in the upper tees valley22
Rapids in the Upper Tees Valley

Rapids are mini-waterfalls

Shallow, slow flowing river due to large amount of friction.

Protruding bands of more resistant strata create steps over which rapids fall - the river bed is ungraded

rapids in the upper tees valley23
Rapids in the Upper Tees Valley

Rapids are mini-waterfalls

Shallow, slow flowing river due to large amount of friction.

Wetted perimeter is large compared to cross sectional area of water - resulting in a low ????????????

Protruding bands of more resistant strata create steps over which rapids fall - the river bed is ungraded

rapids in the upper tees valley24
Rapids in the Upper Tees Valley

Rapids are mini-waterfalls

Shallow, slow flowing river due to large amount of friction.

Wetted perimeter is large compared to cross sectional area of water - resulting in a low hydraulic radius(low efficiency)

Protruding bands of more resistant strata create steps over which rapids fall - the river bed is ungraded

high force waterfall r tees26
High Force waterfall, R. Tees

Huge step in river bed due to igneous intrusion of dolerite into the limestone.

high force waterfall r tees27
High Force waterfall, R. Tees

Huge step in river bed due to igneous intrusion of dolerite into the limestone.

Plunge pool where the dolerite wall is undercut, causing rockfalls and recession of the waterfall upstream

high force waterfall r tees28
High Force waterfall, R. Tees

Huge step in river bed due to igneous intrusion of dolerite into the limestone.

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

Plunge pool where the dolerite wall is undercut, causing rockfalls and recession of the waterfall upstream

high force waterfall r tees29
High Force waterfall, R. Tees

The long profile will be graded over time

Huge step in river bed due to igneous intrusion of dolerite into the limestone.

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

Plunge pool where the dolerite wall is undercut, causing rockfalls and recession of the waterfall upstream

headward erosion offa s dyke31
Headward erosion, Offa’s Dyke

Spring erodes ground over which it flows and lubricates base of cliff, causing slumping and headward erosion

headward erosion r colorado33
Headward erosion, R. Colorado

River seeps out from spring at base and undermines steep cliff, causing rockfalls and headwall recession

headward erosion r colorado34
Headward erosion, R. Colorado

Rivers erode in a headward direction, eating back into plateau

River seeps out from spring at base and undermines steep cliff, causing rockfalls and headwall recession

potholes in r wharfe
Potholes in R. Wharfe

Smooth sculpturing of rock by abrasion, showing evidence of water levels during high discharge events

Vertical erosion is dominant

close up of potholes38
Close-up of potholes

Circular potholes due to eddying motion when river energy is high

close up of potholes39
Close-up of potholes

Circular potholes due to eddying motion when river energy is high

Potholes will join together by abrasion, and deepen by verticalerosion

close up of potholes40
Close-up of potholes

Circular potholes due to eddying motion when river energy is high

Potholes will join together by abrasion, and deepen by verticalerosion

Load is picked up and used to scour or abrade pothole. Load itself becomes rounded by attrition

middle course r tees43
Middle course, R. Tees

Valley opens out, more gentle slopes, wider valley bottom

middle course r tees44
Middle course, R. Tees

Valley opens out, more gentle slopes, wider valley bottom

First signs of meanders

middle course r tees45
Middle course, R. Tees

Valley opens out, more gentle slopes, wider valley bottom

First signs of meanders

Floodplain

middle course r tees46
Middle course, R. Tees

Valley opens out, more gentle slopes, wider valley bottom

First signs of meanders

Floodplain

River channel wider, deeper, greater velocity and discharge

meander r lavant chichester49
Meander, R. Lavant, Chichester

Floodplain

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

meander r lavant chichester50
Meander, R. Lavant, Chichester

Floodplain

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

Steep bank known as the river bluff or cliff, caused by concentrated erosion due to the

meander r lavant chichester51
Meander, R. Lavant, Chichester

Floodplain

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

Steep bank known as the river bluff or cliff, caused by concentrated erosion due to the thalweg

meander r lavant chichester52
Meander, R. Lavant, Chichester

Floodplain

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

Steep bank known as the river bluff or cliff, caused by concentrated erosion due to the thalweg and

helicoidal flow

meander r lavant chichester53
Meander, R. Lavant, Chichester

Floodplain

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

Steep bank known as the river bluff or cliff, caused by concentrated erosion due to the thalweg and

pool

riffle

pool

helicoidal flow

Pools develop at meander bends and riffles in the stretches between bends

meander on the r colorado55
Meander on the R. Colorado

Meander incised into plateau due to rejuvenation

meander on the r colorado56
Meander on the R. Colorado

Meander incised into plateau due to rejuvenation

Different strata show evidence of past climates or hydrological events

meander on the r colorado57
Meander on the R. Colorado

Meander incised into plateau due to rejuvenation

Different strata show evidence of past climates or hydrological events.

Stratum with large boulders must have formed in wetter conditions when higher river discharge carried a greater competence of load

migrating meanders r gongola nigeria59
Migrating meanders, R. Gongola, Nigeria

Former course marked by white sediments

Current channel is braided

lower severn valley61
Lower Severn Valley

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

Very wide floodplain

Very gentle valley side gradients

river terraces r agri s italy63
River terraces, R. Agri, S. Italy

River has been rejuvenated causing renewed vertical erosion - base level has dropped either due to rising land or falling sealevel

river terraces r agri s italy64
River terraces, R. Agri, S. Italy

Flat terraces represent former floodplains

River has been rejuvenated causing renewed vertical erosion -base level has dropped either due to rising land or falling sealevel

flooding in the severn valley66
Flooding in the Severn Valley

Floodplain can be mapped into risk zones high to low

flooding in the severn valley67
Flooding in the Severn Valley

Floodplain can be mapped into risk zones high to low

Floods can be beneficial - they renew soil fertility by depositing sediment on floodplain

flooding in the severn valley68
Flooding in the Severn Valley

Floodplain can be mapped into risk zones high to low

Floods can be beneficial - they renew soil fertility by depositing sediment on floodplain

Floods result in large amounts of sediment transported in the channel

padstow estuary
Padstow estuary

Estuaries are tidal, dominated by marine sediments

At low tide, mudflats are exposed

alluvial fan buttermere lake district72
Alluvial fan, Buttermere, Lake District

Lake Buttermere acts as a local baselevel for the stream, leading to deposition of load in a triangular shape - an alluvial fan

This is the same process that forms major deltas at the coast e.g. R. Nile

braided river swiss alps75
Braided river, Swiss Alps

Daytime snowmelt in summer produces flashyregime

Vast amounts of sediment supplied from frost-shattered valley sides

braided river swiss alps76
Braided river, Swiss Alps

Daytime snowmelt in summer produces flashyregime

Vast amounts of sediment supplied from frost-shattered valley sides

Channel course can change daily due to changes in discharge and loose sediments

summary of channel characteristics 2 landforms83
Summary of channel characteristics(2) Landforms
  • Rapids
  • Waterfall
  • Pothole
  • Meander
  • Bluff/cliff
  • Point bar
  • Pool
  • Riffle
summary of channel characteristics 2 landforms84
Summary of channel characteristics(2) Landforms
  • Rapids
  • Waterfall
  • Pothole
  • Meander
  • Bluff/cliff
  • Point bar
  • Pool
  • Riffle
  • Knick point
  • Braids
  • Alluvial fan
  • Delta
summary of channel characteristics 3 concepts and technical terms86
Summary of channel characteristics(3) Concepts and technical terms
  • Discharge
  • Regime
  • - flashy
  • - regular
  • Capacity
  • Competence
summary of channel characteristics 3 concepts and technical terms87
Summary of channel characteristics(3) Concepts and technical terms
  • Discharge
  • Regime
  • - flashy
  • - regular
  • Capacity
  • Competence
  • Hydraulic radius
  • - cross sectional
  • area
  • - wetted
  • perimeter
summary of channel characteristics 3 concepts and technical terms88
Summary of channel characteristics(3) Concepts and technical terms
  • Discharge
  • Regime
  • - flashy
  • - regular
  • Capacity
  • Competence
  • Hydraulic radius
  • - cross sectional
  • area
  • - wetted
  • perimeter
  • Long profile
  • Graded profile
  • Rejuvenation
  • Base level
summary of channel characteristics 3 concepts and technical terms89

Discharge

  • Regime
  • - flashy
  • - regular
  • Capacity
  • Competence
  • Hydraulic radius
  • - cross sectional
  • area
  • - wetted
  • perimeter
  • Long profile
  • Graded profile
  • Rejuvenation
  • Base level
  • Thalweg
  • Helicoidal
  • flow
  • Meander
  • migration
Summary of channel characteristics(3) Concepts and technical terms