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River Profiles
Waterfalls form when water erodes soft rock and undercuts hard rock.

River Profiles

In GCSE Geography students will look in depth at rivers. This is one of several quizzes on that subject and it looks at river profiles and the features found in each stage of their course.

The course of a river is split into three areas - the upper stage, the middle stage and the lower stage. In the upper course the river is close to its source and is commonly in the hills or valleys travelling down a step gradient. At this stage the rocks it is carrying are large and angular. In the middle course the river is eroding its banks and starting to create the meanders that will carve out a floodplain. In the lower course the river is now close to the mouth, it can’t erode down into the land anymore and now it starts to deposit some of the load that was eroded from high above and that the river has been carrying. The rocks deposited here are smaller and smoother than those in the earlier parts of the river's course.

1 .
How do levees form?
As a river floods, once it leaves the channel the velocity drops and the heaviest material is deposited along the banks, causing a natural build-up of alluvium
As the river under cuts the bank the hydrostatic pressure forces the bank and bed to rise up
As rivers meander they leave behind high deposits of silt on the side of the rivers. These move out into the river and protect the banks
As rivers change levels, the change in velocity causes the river to drop its sediment load and a wall to form across the river
Sediment is dropped from suspension when the river velocity lowers. At the point a river over-tops its banks the velocity drops sharply. Levees are often reinforced or increased artificially as flood protection
2 .
Waterfalls are defined as water cascading from a height. But how do these river features often form?
Waterfalls form when rocks start to swirl round in the current and drill down through the hard layers of rock
Waterfalls form when rivers pick up velocity and need to distribute excess energy
Waterfalls only form when rock splits due to mountain forming processes
Waterfalls form when water flows over different bands of rock, eroding the soft rock and undercutting the hard rock
As the river runs down a hillside it can pass over alternating layers of hard and soft rock, this will mean it erodes the softer rock, eventually undercutting the harder rock and causing it to collapse under its own weight
3 .
As a river moves from the mountains towards the sea its valley shape changes. How might you describe those changes?
The steep sided valley with a narrow channel becomes a wider valley and channel as the river moves towards the sea
The wide channel and the shallow valley become narrower and steeper as the river moves towards the sea
The river gains extra energy as it moves towards the sea and it cuts into the valley making it steeper
The river in the upper section cuts back the valley sides to form a wide u-shaped valley. As the river moves towards the sea the valley narrows but the channel widens
As the river moves towards the coast the river valley becomes wider as the meanders cut back the valley sides
4 .
If you took a slice of a river from the source to the mouth this would be called what?
A cross profile
A long profile
A transect
A course line
The long profile measures the changes in the river from the source to the baseline - the lowest point the river can erode to, normally sea level
5 .
What is a levee?
A wall built across a river to increase the height of the water up river
A structure built at right angles to the flow to build up sediment to protect a beach or wall
A ridge of sediment deposited alongside a river, or a manmade embankment to stop the river overflowing
The build-up of sediment in the middle of a river raising the river bed and causing the river to flood
Levees are natural or artificial barriers to flooding. Often the river flow and channel may be higher than the land surrounding them due to deposition building up the bed of the river and the height of the levees
6 .
Which of the following is the typical order of features in a river, from its start to discharging into the sea?
Source, waterfall, meanders, rapids, estuary
Source, waterfall, rapids, meanders, estuary
Waterfall, estuary, meanders, rapids, source
Source, estuary, waterfalls, meanders, rapids
A river starts at its source and normally finishes at the sea at its estuary. Meanders are only found in the middle and lower sections whilst rapids and waterfalls are commonly found in the upper sections
7 .
What shape would a typical cross section of a river in its upper course be?
Narrow and shallow
Wide and shallow
Narrow and deep
Wide and deep
Try and imagine the river when you are answering questions like this. In the mountains you can imagine the narrow shallow stream that you can often wade across, or ford
8 .
Which of these areas is the most suitable for dams and reservoirs?
A very shallow and wide valley with soft geology on either side
A wide and shallow valley with settlements and structures built inside
A flat flood plain
A steep valley with hard geology on either side
Dams are normally built in valleys where the water can be contained on two sides by the valley itself. Steep valleys with hard geology increase the amount of water that can be stored behind the dam, and the geology decreases the risk of dam collapse
9 .
What sort of features would you find in the upper course of a river?
Rapids, wide shallow river, and high energy meanders
V-shaped valley, interlocking spurs, and waterfalls
Deep incised valleys and U shaped profiles
Depositional structures, steep sided valleys, and sharp angular rocks
In the upper course of the river the river tends to erode vertically down, winding round tougher rock structures, leading to the interlocking spurs and V-shaped valleys
10 .
In the upper course, as the river erodes rock away, tapering ridges are formed. What are these known as?
Meanders
Glaciers
Interlocking spurs
Breccias
As the river erodes it takes the path of least resistance, often winding between sections of tougher rocks, leading to these tapering ridges of interlocking spurs
You can find more about this topic by visiting BBC Bitesize - River environments

Author:  Ruth M

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