How do rivers change downstream? (the long (river) profile)

What processes can you see happening in these 3 river landscapes?

The long (river) profile Source Make a sketch of the long river profile in your book Upper Height above sea level Middle Lower Mouth Distance from source

UPPER COURSE OF RIVER VERTICAL EROSION LOWER COURSE OF RIVER LATERAL EROSION Why do you think there is vertical erosion in the upper course (near the source, in the upland areas) and lateral erosion in the lower course (near the mouth)?

The diagram here shows the changes that happen in a river from its source (upper course) to its mouth (lower course) Using the diagram to help you, complete the missing words on the worksheets “what processes occur in a river?” and “the long profile of a river” Upstream Downstream Discharge Occupied channel width Channel depth Average velocity Load quantity Load particle size Channel bed roughness Slope angle (gradient)

The long profile of a river The long profile of a river runs from its _________ to the point where it enters the sea, a lake or joins another and larger river. The character of the long profile changes d_______. Overall it has a smooth concave shape. It is steep and in places irregular where the river is flowing well above _______ level in upland country. The irregularities occur where _____ rock outcrops run across the valley. Natural _______ and reservoirs can also disrupt the smoothness of the long profile. However, the profile becomes much gentler and smoother as the river runs through _____ land country and reaches its destination. Changes in the character of river landforms are associated with these changes in the long profile.

The long profile of a river The long profile of a river runs from its source to the point where it enters the sea, a lake or joins another and larger river. The character of the long profile changes downstream. Overall it has a smooth concave shape. It is steep and in places irregular where the river is flowing well above sea level in upland country. The irregularities occur where hard rock outcrops run across the valley. Natural lakes and reservoirs can also disrupt the smoothness of the long profile. However, the profile becomes much gentler and smoother as the river runs through lowland country and reaches its destination. Changes in the character of river landforms are associated with these changes in the long profile.

Erosion takes place in various ways throughout the course of the river Erosion takes place in various ways throughout the course of the river. In the _______ course of the river, the gradient is much steeper and therefore there tends to be more _________ erosion (downwards). However, in the middle and ________ courses of the river, the land becomes flatter and therefore there is more ______ erosion (side to side). Material is transported throughout the river. In the upper course, the river has more energy so it can transport ________ material. As this material is transported downstream, it is subject to more erosion so it ______ in size. Further ______ stream the river also begins to loose its’ energy, so much more of the material gets ____________ In the upper course of the river, the gradient of the slopes are ________. There is generally also much more active w__________ taking place, so this area is sometimes referred to as a sediment supply zone. There are usually a higher density of tributaries in the upland areas and these collect the _________ to transport it further d_____________.

Erosion takes place in various ways throughout the course of the river Erosion takes place in various ways throughout the course of the river. In the UPPER course of the river, the gradient is much steeper and therefore there tends to be more VERTICAL erosion (downwards). However, in the middle and LOWER courses of the river, the land becomes flatter and therefore there is more LATERAL erosion (side to side) Material is transported throughout the river. In the upper course, the river has more energy so it can transport MORE material. As this material is transported downstream, it is subject to more erosion so it DECREASES in size. Further DOWNstream the river also begins to loose its’ energy, so much more of the material gets DEPOSITED In the upper course of the river, the gradient of the slopes are STEEP. There is generally also much more active WEATHERING taking place, so this area is sometimes referred to as a sediment supply zone. There are usually a higher density of tributaries in the upland areas and these collect the MATERIAL to transport it further DOWNSTREAM.

How do the river landforms and processes change in different parts of the river? Read p.10-13 of Longman Geography for IGCSE and complete the table to show how the characteristics of a river change in the upper, middle and lower courses.

In which part of the river have these images been taken? 1 3 4 2 6 7 8 5 10 11 12 9

Task In groups work out the cause of the following landforms Use the correct terminology and 3 diagrams for each Think… 4 mark question… Upper Course V shaped valley Interlocking Spurs Waterfall Lower Course Meander Ox-Bow lake Flood Plain Levee

Fieldwork – how would you measure Depth, width, bedload size, velocity?