Lesson Y7-U03-L07

Y7-U03-L07 Reading the Flow: Hydrographs Quiz: KS3 Geography, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson Y7-U03-L07, Reading the Flow: Hydrographs: 20 multiple choice questions for the KS3 Geography (National Curriculum), Unit 3: Year 7: Rivers and the Water Cycle, written with Revision Ninja.

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The 20 questions

  1. What unit is river discharge measured in?

    • Cumecs, cubic metres of water per second
    • Degrees of slope per kilometre of the valley floor
    • Kilometres of channel that the river flows each day
    • Millimetres of rain falling on the basin each hour

  2. What do the bars at the top of a hydrograph show?

    • The width of the river channel at each hour
    • The river's discharge at each hour
    • The rainfall in millimetres for each hour
    • The height of the land above sea level

  3. What does the curved line on a hydrograph show?

    • The gradient of the valley sides over time
    • The temperature of the river at each hour
    • The rainfall in millimetres for each hour
    • The discharge, or how much water flows in the river

  4. What is peak discharge?

    • The time gap between peak rainfall and the moment the river flow starts to rise
    • The highest point of the discharge curve, when the river is fullest
    • The lowest point of the river before a storm arrives over the basin, at the start
    • The total rainfall that falls during the storm across the whole drainage basin

  5. What is lag time?

    • The gap in time between peak rainfall and peak discharge
    • The number of hours the river stays at its lowest
    • The time it takes for the rain to start falling
    • The time between two storms in the same week

  6. Which peak happens first on a hydrograph?

    • Peak storage, when the water sinks into the soil
    • Peak lag time, when the gap is biggest
    • Peak discharge, when the river is at its fullest
    • Peak rainfall, when the rain bars are tallest

  7. When reading a value on a hydrograph, which order should you follow?

    • Up to the line first, then along to the hour
    • Down from the top bars, then along the bottom axis
    • Along to the hour, up to the line, then across to the number
    • Across to the number first, then down to the time

  8. What does the bottom axis of a hydrograph show?

    • The rainfall in millimetres for each bar
    • Time, in hours, going from left to right
    • The height of the land above sea level
    • The discharge in cumecs at each point

  9. A hydrograph shows peak rainfall at hour 6 and peak discharge at hour 16. What is the lag time?

    • 22 hours
    • 10 hours
    • 6 hours
    • 4 hours

  10. Peak rainfall is at hour 5 and peak discharge at hour 14. What is the lag time?

    • 9 hours
    • 5 hours
    • 14 hours
    • 19 hours

  11. Peak rainfall is at hour 4 and peak discharge at hour 12. Which answer gives the lag time correctly?

    • 3 hours, found by dividing the difference between the two peaks in half
    • 8 hours, subtracting peak rainfall from peak discharge
    • 16 hours, found by adding the two peak hours together to make a total
    • 12 hours, which is simply the hour of peak discharge with nothing taken away

  12. On a hydrograph, the discharge at hour 0, before a storm, is about 8 cumecs. What does that tell you about the river at that time?

    • The river was low, flowing gently before the rain arrived
    • The river was completely dry with no water in it
    • The river was already at its peak flood level
    • The river had just reached its source in the hills

  13. A hydrograph's discharge peaks at hour 16 at about 38 cumecs. What is the best description of the river at that hour?

    • The river is at its fullest, carrying the most water
    • The river is at its lowest, after the storm has passed
    • The river is at its source, high in the hills
    • The river has no water flowing, so the channel is dry

  14. Why does peak discharge happen hours after the rain has fallen?

    • The rain takes hours to start falling after the storm
    • The river is frozen until the rain has stopped falling
    • The river must fill its channel before any water can move
    • Rainwater takes time to flow over the land and soil into the river

  15. A storm falls on a city with many hard, paved surfaces. How would its hydrograph most likely change?

    • A shorter lag time, because water runs off quickly into the river
    • Peak discharge would happen before peak rainfall
    • No change, because paving has no effect on run-off
    • A longer lag time, because water soaks into the paving

  16. Which change to a hydrograph would most likely show a flood arriving quickly?

    • A river with no rainfall recorded on its bars
    • A lower peak discharge with the same rainfall
    • A longer gap between peak rainfall and peak discharge
    • A shorter gap between peak rainfall and peak discharge

  17. Explain why a hydrograph shows discharge continuing to rise after the rain has stopped.

    • The rain bars are still growing after the storm ends, adding more water to the river
    • The river has been dammed by the sea and cannot flow out until the tide turns
    • The discharge is measured in mm, so the number keeps going up as the hours pass
    • Water from far upstream and the land still takes time to reach the river

  18. Two rivers had the same storm, but one peaked after 4 hours and the other after 12 hours. Which reason best explains this?

    • The 12 hour river must have had more rain than the 4 hour river during the storm
    • Rivers in the same storm always peak at the same hour, so the difference is a mistake
    • The 12 hour river may have a bigger, slower catchment, so water takes longer to reach it
    • The 4 hour river has far less rain falling on its basin than the other river did

  19. Which statement about a hydrograph's peaks is correct?

    • Peak rainfall always comes after peak discharge on a storm graph
    • Peak discharge and peak rainfall always happen in the same hour
    • Peak rainfall is measured in cumecs, and discharge in millimetres
    • Peak discharge comes after peak rainfall, with the lag time between them

  20. A pupil says the river floods the moment it rains. Which correction is right?

    • The river floods before the rain, because the lag time comes first
    • Floods happen only in winter when the rivers are frozen
    • The river floods at the same moment as the rain, but only briefly
    • The river rises after the rain, because water must flow to it, creating a lag

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