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The Changes downstream in a river valley in a river valley RIVER STUDIES.

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Presentation on theme: "The Changes downstream in a river valley in a river valley RIVER STUDIES."— Presentation transcript:

1 The Changes downstream in a river valley in a river valley RIVER STUDIES

2 The Hydrologic Cycle Infiltration = Groundwater System Infiltration = Groundwater System Runoff = Surface Water System Runoff = Surface Water System

3 Satellite view of river drainage, Middle East What is this features?

4 Upper valley characteristics

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6 Vshape valley, vertical erosion dominant

7 Upper valley characteristics Vshape valley, vertical erosion dominant Interlocking spurs

8 Upper valley characteristics Vshape valley, vertical erosion dominant Interlocking spurs Slumping and landslides - very active hill slopes

9 Upper valley characteristics Vshape valley, vertical erosion dominant Interlocking spurs Slumping and landslides - very active hill slopes Narrow, shallow channel, low velocity and discharge

10 Upper valley characteristics Vshape 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

11 Interlocking spurs, Robinson, Lake District A typical upper course valley with interlocking spurs, steep valley sides and active slope processes

12 River load in upper course Boulders are large and semi-rounded, due to attrition within the load and abrasion with the stream bed and banks Why are they rounded?

13 Rapids in the Upper Tees Valley WHAT IS A RAPID?

14 High Force waterfall, R. Tees WHAT IS A WATERFALL?

15 High Force waterfall, R. Tees 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?

16 Waterfall formation Look at the diagram, How is a waterfall formed?

17 High Force Waterfall R. Tees

18 Close-up of potholes How are these formed?

19 Potholes, human scale!!

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21 Erosion Processes is when the river is loaded with material in suspension and scours away at the river banks. (Sandpaper effect) 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 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 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. is when bed load collides into each other with the current flow and breaks down into smaller particles. Abrasion (Corrasion) - Hydraulic Action - Corrosion - Attrition -

22 Middle course, R. Tees HOW DOES THIS DIFFER FROM THE UPPER SECTION?

23 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 WHAT DO YOU THINK THE ARROWS POINT TO?

24 Meandering Rivers WHAT IS A MEANDER?

25 Formation of Meanders

26 Point bar deposits

27 Point Bar Deposits Point bar deposits grows laterally through time

28 Meander, R. Lavant, Chichester

29 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? WHICH WAY IS THIS MEANDER MOVING?

30 Cut bank erosion (River Cliff) Point bar deposits } Meander loop WHERE IS EROSION TAKING PLACE? WHERE IS DEPOSTION TAKING PLACE? A B C D E F

31 Meander on the R. Colorado WHY IS DEPOSITION OCCURING HERE?

32 How did these meanders form?

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34 REVISION: What River features do you get here?

35 Migrating meanders, R. Gongola, Nigeria WHY ARE THEY MIGRATING?

36 What happens to the river when it moves to the middles course Gradient becomes less steep Gradient becomes less steep River continues to erode vertically but LATERAL erosion now occurs in MEANDERS River continues to erode vertically but LATERAL erosion now occurs in MEANDERS 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 being carried? What factors effect how much load is being carried?

37 Transportation What are the four methods of transportation? What are the four methods of transportation? Traction - is when large particles roll along the river bed 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. 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. 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. Solution - is when dissolved material is carried.

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39 Lower Course: Severn Valley

40 Lower 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

41 Flood Plains The entire floodplain can become covered with water during floods. HOW DO YOU THINK THE TERRACES WERE FORMED?

42 Ox Bow Lake Formation LOOK AT THE DIAGRAM & EXPLAIN THERE FORMATION

43 Formation of an Oxbow

44 Ox Bow lake on Mississippi

45 Levee formation

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

47 Delta Formation WHAT IS A DELTA? DEPOSITON OF MATERIAL BY THE RIVER WHEN IT ENTERS THE SEA DEPOSITON OF MATERIAL BY THE RIVER WHEN IT ENTERS THE SEA WHY DOES IT DROP ITS SEDIMENT

48 Mississippi Delta from Space MISSISSIPPI

49 The Nile Delta from space River Nile

50 Estuary 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? RAISED VALLEY SIDES USING YOUR ATLAS FIND AN ESTUARY (LOOK AT THE RIVER THAMES) USING YOUR ATLAS FIND AN ESTUARY (LOOK AT THE RIVER THAMES)

51 USING YOU ATLAS LOCATE THE RHONE DELTA USING YOU ATLAS LOCATE THE RHONE DELTA The Rhone Delta

52 The Rhone Delta S. France Look 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?

53 The Rhone Delta WHY HAS A DELTA FORMED HERE? LOOK AT P 39 WHY HAS A DELTA FORMED HERE? LOOK AT P 39

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55 Summary of valley characteristics

56 The River Tees TRY AND FIND THE RIVER TEES IN YOUR ATLAS HINT LOOK AT THE MAP TRY AND FIND THE RIVER TEES IN YOUR ATLAS HINT LOOK AT THE MAP

57 Land Use in Drainage Basin of River Tees WHAT IS THE AREA IN EACH BOX?

58 Upper Tees WHAT HUMAN INFLUENCES EXIST IN THE MAPS? COW GREEN RESERVOIR

59 The Upper Tees Cronkley Scar WHAT LAND USES CAN YOU SEE IN THE PHOTO? WHAT ARE THE KEY GEOGRAPHCIAL FEATURES YOU CAN SEE IN THE PHOTOGRAPH WHAT ARE THE KEY GEOGRAPHCIAL FEATURES YOU CAN SEE IN THE PHOTOGRAPH MOORLAND STEEP VALLEY SLOPE DEBRIS TURBULENT RIVER CHANNEL TURBULENT RIVER CHANNEL

60 Upper Tees WHAT IS THE NAME OF THE WATERFALL?

61 The Lower Course Tees HOW HAS THE RIVER AND LAND USE CHANGED? HOW HAS THE RIVER AND LAND USE CHANGED? FLAT VALLEY FLOOR WIDE MEANDERS URBAN SETTLEMENT URBAN SETTLEMENT

62 WHAT LAND USE CAN YOU SEE IN THE PHOTOGRAPH? The Lower Tees TEESMOUTH ESTUARY

63 The River meets the Sea

64 LOOK AT P42 WHAT DO YOU THINK THE PHOTOS SHOW? LOOK AT P42 WHAT DO YOU THINK THE PHOTOS SHOW? WHAT IS THE FUNCTIONOF THE BARRAGE? River Management

65 Formation of the Mississippi River Delta Early delta More recent delta sediments Modern delta

66 Causes of Floods A Flood can occur when a river exceeds its bank full stage and water will subsequently inundate the adjacent surrounding area. 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. 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. 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. 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. Urbanisation - tarmac and concrete surfaces are impermeable and lead to an increase in surface runoff.

67 Flood Control and Management There are a number of ways managing floods: There are a number of ways managing floods: 1. Afforestation - planting trees increases interception rates and reduces surface runoff. 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. 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. 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. 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. 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. 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. 7. Revetments and Channel Walls - strengthen river banks from erosion.


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