Exam-style Questions: River Profiles

  1. For any named drainage basin, explain the main processes operating within it.

    (Marks available: 15)

    Answer

    Answer outline and marking scheme for question: 1

    A long answer that you will need to plan, and should spend approximately half an hour answering. Careful consideration of the ways processes interact to result in a high or low probability of flooding is vital. Figures and reference to a storm event should be used to support your answer.

    Begin with a brief outline of the main characteristics of your drainage basin:

    "The drainage basin of the River X is located in... It has an elongated shape, and the relief is predominantly low lying. The climate is mild with winter temperatures rarely falling below freezing."

    Reference to the following is required:

    • Basin size / shape / relief
    • Land use and vegetation (farming, forestry etc.)
    • Any urban areas
    • Climate
    • Rock and soil type

    How these factors influence the processes of infiltration, evapotranspiration, soil moisture stores etc.

    For example: " Discharge for the river is highest from October to January when numerous depressions pass over the area. Evapotranspiration is reduced at this time as a result of low temperatures and limited interception a result of leaf loss from deciduous trees. These factors combine to increase the flood risk at this time of the year. An example of this was shown in..."

    (Marks available: 15)

  2. a) What are the chief processes operating in a drainage basin system?

    (6 marks)

    b) How can change to land use in a river channel limit flooding? You should include references to a named river.

    (12 marks)

    (Marks available: 18)

    Answer

    Answer outline and marking scheme for question: 2

    a) You need a diagram - without it the maximum marks will be 4. The following are required with some brief explanation.

    • Outputs: transpiration, evaporation, river runoff
    • Inputs
    • Stores
    • Transfers

    b) Modification you should relate to in your named drainage basin include:

    • Zoning of land use
    • Measures to conserve soil (forestation to reduce runoff)
    • Land use planning measures, for example, house building limited to higher land away from flood risk
    • Lower density of building on flood plain
    • Land uses that keep the floodplain for its intended use (water storage and wetland) these lower the flood risk
    • Reservoirs to store water
    • Channels cut to divert flow in times of heavy rainfall
    • Channel realignment
    • Banks and levees constructed
    Marks: What to look for:
    9 - 12 Annotated diagram of measures, which explains clearly land use and channel modifications and how these reduce flood risk. A deep understanding is displayed.
    4 - 8 Diagram, but incomplete annotation. Links to how methods reduce flood risk is less clear.
    1 - 3 Poor diagram, very little annotation. Little understanding demonstrated.

    (Marks available: 18)