Faster water on the outside of the bend causes erosion (river cliff); slower water on the inside causes deposition (slip-off slope) — over time the channel shifts laterally. Learn it step by step →
Rivers & Coasts is a core part of GCSE Geography. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
Hydraulic actionForce of water hits and breaks rock
AbrasionRocks scrape and grind against bedrock
AttritionRocks knock together and become smoother/smaller
Solution (erosion)Acidic water dissolves rocks (limestone, chalk)
TractionHeavy rocks rolled along river/sea bed
SaltationPebbles bounce along the bed
Hard engineeringBuilt structures (sea wall, groynes, dam)
Soft engineeringWorking with nature (beach nourishment, planting)
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Learn Rivers & Coasts step by step
Free interactive mini-lessons: short screens, worked examples and quick checks. Pick your exam board:
Questions where students often pick the tempting wrong answer — make sure you know the right one:
Why do meanders migrate across a floodplain?✗ Meanders form because rivers flow around obstacles like rocks.✓ Faster water on the outside of the bend causes erosion (river cliff); slower water on the inside causes deposition (slip-off slope) — over time the channel shifts laterally.
What is lag time on a storm hydrograph?✗ Lag time is how long the storm itself lasts.✓ The time between peak rainfall and peak river discharge — affected by drainage basin shape, land use, soil saturation and vegetation.
What is hydraulic action in a river?✗ Hydraulic action is when rocks in the river smash into each other.✓ The force of moving water itself compressing air into cracks in the river bank or bed, weakening rock until pieces break off — no sediment needed.
How do waves erode a cliff?✗ Waves erode cliffs by pushing water against the rock until it breaks.✓ Through hydraulic action (water compressing air in cracks), abrasion (waves hurling rocks against the cliff) and solution (dissolving rocks such as chalk and limestone); attrition wears down the eroded rocks themselves, not the cliff.
What is longshore drift?✗ Sand moves along the beach because tides pull it sideways.✓ The zigzag movement of sediment along a coast caused by waves approaching at an angle (swash up the beach) and gravity returning water perpendicular (backwash).
Practise Rivers & Coasts — free games
Test yourself with these quick revision games for this topic:
