6Upper valley characteristics “V”shape valley, vertical erosion dominant
7Upper valley characteristics “V”shape valley, vertical erosion dominantInterlocking spurs
8Upper valley characteristics “V”shape valley, vertical erosion dominantInterlocking spursSlumping and landslides - very active hill slopes
9Upper valley characteristics “V”shape valley, vertical erosion dominantNarrow, shallow channel, low velocity and dischargeInterlocking spursSlumping and landslides - very active hill slopes
10Upper valley characteristics “V”shape valley, vertical erosion dominantNarrow, shallow channel, low velocity and dischargeInterlocking spursSlumping and landslides - very active hill slopesLarge bed load derived from upstream and from valley sides
11Interlocking spurs, Robinson, Lake District A typical upper course valley with interlocking spurs, steep valley sides and active slope processes
12River load in upper course Why are they rounded?Boulders are large and semi-rounded, due to attrition within the load and abrasion with the stream bed and banks
13Rapids in the Upper Tees Valley WHAT IS A RAPID?
14High Force waterfall, R. Tees WHAT IS A WATERFALL?
15High Force waterfall, R. Tees Waterfall creates gorge as it recedes upstream by eroding the base and neckWhat is this feature called?HOW IS A GORGE FORMED?Plunge pool
16Waterfall formationLook at the diagram, How is a waterfall formed?
21Erosion ProcessesCorrosion -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.
22Middle course, R. TeesHOW DOES THIS DIFFER FROM THE UPPER SECTION?
23Middle course, R. Tees WHAT DO YOU THINK THE ARROWS POINT TO? Valley opens out, more gentle slopes, wider valley bottomFirst signs of meandersRiver channel wider, deeper, greater velocity and discharge
35Migrating meanders, R. Gongola, Nigeria WHY ARE THEY MIGRATING?
36What happens to the river when it moves to the middles course Gradient becomes less steepRiver continues to erode vertically but LATERAL erosion now occurs in MEANDERSWhat is MEANDER MIGRATION ?Name three effects it have on the valley?What factors effect how much load is being carried?
37Transportation What are the four methods of transportation? Traction - is when large particles roll along the river bedSaltation - 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.
50Estuary FormationHOW 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 SIDESUSING YOUR ATLASFIND AN ESTUARY(LOOK AT THE RIVER THAMES)
51The Rhone DeltaUSING YOU ATLASLOCATE THE RHONEDELTA
52The Rhone Delta S. France Look at p39 and identify theKEY FEATURES CAN YOUSEE IN THE SATELLITE PHOTO?
53The Rhone DeltaWHY HAS A DELTAFORMED HERE? LOOK AT P 39
64River Management WHAT IS THE FUNCTIONOF THE BARRAGE? LOOK AT P42 WHAT DO YOU THINKTHE PHOTOS SHOW?
65Formation of the Mississippi River Delta More recent delta sedimentsModern deltaEarly delta
66Causes of FloodsA 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.
67Flood Control and Management 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.