Hydrographs and Flooding (OCR GCSE Geography A (Geographical Themes)): Flashcards
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Practise the cards
15 cards from this deck
River discharge definition
River discharge definition
Volume of water flowing in a river per second
River discharge measurement unit
River discharge measurement unit
Cubic metres per second
What hydrographs show
What hydrographs show
Discharge changes over time in relation to rainfall
Peak discharge meaning
Peak discharge meaning
Maximum amount of water held in the channel
Peak rainfall meaning
Peak rainfall meaning
Maximum amount of rainfall (millimetres)
Lag time definition
Lag time definition
Time between peak rainfall and peak discharge
Rising limb on hydrograph
Rising limb on hydrograph
Shows the increase in discharge
Falling limb on hydrograph
Falling limb on hydrograph
Shows return of discharge to normal/base flow
Base flow meaning
Base flow meaning
The normal discharge of the river
Effect of no vegetation on lag time
Effect of no vegetation on lag time
Water runs off quicker, creating short lag time
Effect of vegetation on lag time
Effect of vegetation on lag time
Plants intercept rain, creating longer lag time
What does short lag time increase?
What does short lag time increase?
Flood risk
How prolonged rainfall affects flood risk
How prolonged rainfall affects flood risk
Soil becomes saturated, increasing runoff and discharge
How deforestation affects flood risk
How deforestation affects flood risk
Removes trees that intercept and absorb water, increasing risk
How impermeable surfaces affect runoff
How impermeable surfaces affect runoff
Concrete/roads increase runoff to rivers