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Edexcel GCSE Geography

River landscapes and flooding — Edexcel GCSE Geography revision

Free revision notes, key terms, common exam traps and 5 practice questions with answers. About 8 minutes to read.

Processes

  • Erosion: hydraulic action (water force), abrasion (load scraping the bed), attrition (load colliding and rounding) and solution (chemical dissolving).
  • Transport: traction, saltation, suspension and solution. Deposition happens when velocity falls — inside meander bends, at the mouth and on the floodplain during floods.
  • The long profile steepens upstream; the cross profile widens and deepens downstream as discharge and efficiency increase, even though gradient falls.

Landforms

  • Upper course: V-shaped valleys, interlocking spurs, waterfalls and gorges formed where hard rock overlies softer rock and a plunge pool undercuts the cap rock.
  • Middle course: meanders with fast flow and erosion on the outer bend (river cliff) and deposition on the inner bend (slip-off slope); oxbow lakes form when the neck is cut through during a flood.
  • Lower course: floodplains built by repeated overbank deposition, levees from coarse material dropped at the channel edge, and estuaries with mudflats.

Key terms

Hydraulic action
Erosion by the sheer force of water forcing air into cracks.
Attrition
Load particles colliding and becoming smaller and rounder.
Discharge
Volume of water passing a point per second, in cumecs.
Lag time
Time between peak rainfall and peak discharge.
Meander
A bend in a river with erosion outside and deposition inside.
Oxbow lake
A cut-off meander loop left as a curved lake.

Common exam traps

  • Saying rivers get shallower downstream — the channel gets wider AND deeper even though the gradient falls.
  • Confusing attrition (load hitting load) with abrasion (load hitting the bed and banks).
  • Describing an oxbow lake as forming slowly by deposition alone — the neck is usually breached during a flood.

Practice questions with answers

  1. 1. Which process rounds pebbles as they travel downstream?

    • • Hydraulic action
    • • Abrasion
    • • Attrition
    • • Solution

    Answer: Attrition

    Particles collide with each other and become smaller and rounder.

  2. 2. Deposition on the inside of a meander bend forms a:

    • • River cliff
    • • Slip-off slope
    • • Levee
    • • Gorge

    Answer: Slip-off slope

    Slower flow inside the bend drops sediment as a gentle shelf.

  3. 3. Explain how a waterfall retreats to form a gorge.

    Answer: Softer rock is undercut, the hard cap collapses into the plunge pool and the waterfall retreats upstream leaving a steep gorge

    Sequence undercutting, collapse and retreat for full marks.

  4. 4. Which transport process carries fine particles within the flow?

    • • Traction
    • • Saltation
    • • Suspension
    • • Solution

    Answer: Suspension

    Fine silt and clay stay held within the moving water.

  5. 5. Explain why urbanisation increases flood risk.

    Answer: Impermeable surfaces and drains reduce infiltration and speed run-off, shortening lag time and raising peak discharge

    Link surface change to hydrograph shape.

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