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GET
THAT GRADE!
Unit 03 |
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Topic
Task 3
You must make sure that you know the features and processes of a river system. |
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Explain
each of the following key terms
• drainage basin (or catchment area)
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watershed
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source
• tributary
• confluence
• mouth
or estuary
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A diagram or sketch would help you remember these |
What
are the inputs into a river system?
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precipitation (link this to the hydrological cycle)
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eroded rock and soil (the load of the river)
How
is water transferred in the river system?
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overland flow or run off
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throughflow
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groundwater flow
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uptake by plants
Water gets into the soil or down to the water table by infiltration.
How can water
be stored in the system?
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lakes, reservoirs, ponds, etc.
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groundwater
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soil moisture
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ice caps and glaciers
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plant moisture
What are
the outputs from the system?
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flow to the sea
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use by the population for farming, industry or domestic use
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evaporation from the surface
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transpiration by plants
How do rivers
erode?
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hydraulic action
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attrition
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corrasion
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corrosion
How do rivers transport eroded material?
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suspension
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saltation (or bouncing)
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traction (rolling or dragging)
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solution
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A labelled diagram would certainly help you remember these! |
| Deposition | |
| 1. | Why do rivers sort material when they deposit it? |
| 2. | When is material deposited? (Think about changes in the amount of energy that the river has.) |
| 3. | What type of material is deposited first? |
| 4. | What type of material can be carried furthest? (Think what the river can still carry, even when it has lost almost all of its energy.) |
| River valleys | |
| 1. | River valleys in highland regions are often deep, narrow and with steep sides. Why? |
| 2. | Lowland river valleys are usually broad with flat bottoms and wide floodplains. Why? |
Explain both these answers by referring to the balance between sideways (lateral) erosion and downwards (vertical) erosion.
| Waterfalls | |
| Label
this diagram of a waterfall to show: • how it was formed • why it retreats upstream |
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| . then learn it. |
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Your syllabus probably lists the features that you need to learn. Ask your teacher for a list of these, or look at a copy of the syllabus. |
River
floodplains
This diagram shows some of the features to be found on a river floodplain.
Label them and make notes around the diagram on a printed copy to show
how each labelled feature was formed.
This is an enlargement of a meander from the diagram above. Print it out
and label the diagram to show where:
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the current is strongest, and weakest
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erosion and deposition are taking place
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how the two points above are linked
Storm
hydrographs
The following diagram shows a storm hydrograph. Print
it out and label:
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peak rainfall
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peak flow
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lag time
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rising limb
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falling limb
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base flow
1.
When will this river cause most erosion?
2. When will it be most likely to deposit material?
Storm hydrographs have a short lag time and a high peak flow if water gets to the river quickly. Anything that speeds up run-off and/or slows down infiltration will reduce the lag time and make floods more likely.
3.
List six ways that the lag time could be reduced in a river basin.
4.
When is erosion most likely to happen on the hydrograph? (When is there
most energy available to do the work of erosion?)
How
can a river basin best be managed?
The proper management of a river basin should aim to:
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provide enough water for all people in the basin
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control flooding
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control erosion and deposition
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conserve habitats and wildlife
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manage waste disposal and control pollution
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make water available for leisure pursuits
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allow boats to navigate the basin
| For a named river basin find out about as many of these management priorities as possible. In particular you should find out about how floods are controlled. Flood control might include: | |
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storing water in reservoirs • storing water in flood overspill areas • speeding up run off from some areas by: |
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straightening the channel - deepening the channel - putting drains in some areas to take water off the land - reducing blockages in the river by: - clearing debris trapped under bridges - clearing vegetation from growing in the river channel - dredging the river - slowing down the flow of the river in some places (usually upstream) so that it does not all reach critical points at the same time. |
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There are obviously going to be conflicts between the different aims. For instance, one way to reduce flooding may be to clear all the vegetation growing on the river banks in order to speed up the river's flow. However, this will destroy wildlife habitats. You should be able to discuss such issues clearly. Make sure that you can put forward the views of both sides. Sometimes examiners ask you to give the views of different groups who might be interested in an issue. Do try to give the names and views of real groups. For example, try not to write about 'environmentalists' without being specific. You could write about local county Wildlife Trust, who try to conserve wildlife habitats in your area; or the Environment Agency, which is a government organisation which manages all the different interests in a river basin; or Greenpeace, an organisation which sometimes takes direct action to try and protect the environment. |
