The river long profile and how processes change downstream; the formation of erosional landforms (waterfalls, gorges, interlocking spurs) and landforms of erosion and deposition (meanders, ox-bow lakes, floodplains, levees); and a UK river landscape case study.

What this dot point is asking

This is OCR GCSE Geography B (J384) Component 1, Our Natural World, within Distinctive Landscapes. OCR expects you to describe the river long profile and how processes change from source to mouth, explain how erosional landforms (waterfalls, gorges, interlocking spurs) and landforms of erosion and deposition (meanders, ox-bow lakes, floodplains, levees) develop, and study one UK river landscape in detail. As with the coast, OCR sets the requirement and your school chooses the river.

The long profile and changing processes

The cross-section also changes: a narrow, deep, V-shaped valley upstream becomes a wide, flat-floored valley downstream.

Upper-course landforms

In the upper course, the river has little water but a steep gradient, so it cuts down into the land. The valley is a steep-sided V-shape, and where the river winds around bands of resistant rock it leaves interlocking spurs of higher land projecting from alternate sides.

Middle and lower-course landforms

In the middle course, lateral erosion forms meanders: faster flow on the outside of a bend erodes a steep river cliff, while slower flow on the inside deposits a gentle slip-off slope. Where a meander becomes very pronounced, erosion narrows its neck; during a flood the river cuts straight across, and deposition seals off the old loop to leave an ox-bow lake.

In the lower course, the river is wide and slow but heavily laden, so it deposits.

• A floodplain is the wide, flat valley floor built up by repeated flooding, which spreads fine silt (alluvium) and makes the land fertile.
• Levees are raised banks of coarser sediment deposited at the channel edge when the river floods and suddenly loses energy; over time they build up natural embankments.
• A delta can form where the river meets the sea or a lake and drops its remaining load.

A distinctive UK river

OCR requires one UK river landscape studied in depth. A common choice is the River Tees in north-east England: it rises in the high Pennines, where the gradient is steep and the river cuts the spectacular waterfall High Force over hard whinstone and a gorge below it; in its middle and lower courses it develops large meanders and a broad floodplain before reaching the North Sea at Middlesbrough. Learn how the landforms change down the profile and how people use and manage the valley.

Try this

Q1. Describe how a river's long profile changes from source to mouth. [3 marks]

• Cue. Steep gradient near the source, gradually flattening to a gentle gradient at the mouth.

Q2. Explain how an ox-bow lake forms from a meander. [4 marks]

• Cue. Erosion narrows the meander neck, a flood breaks through the shorter route, deposition seals off the old loop, leaving an ox-bow lake.