RIVER PROCESSES + LANDFORMS

How do rivers shape the land?

Recap quiz

River drainage basins

• A drainage basin = an area of land drained by one river

• Part of the hydrological cycle where water is transferred in a continuous cycle between the sea, atmosphere and the land.

• As the river flows downstream its characteristics and landforms change through the three main sections of:

The Upper Course The Middle CourseThe Lower Course

What is it? What stage of the river is it found in?

What is it like?

Watershed N/A

Source

V-shaped valley

Interlocking spurs

Tributory + Confluence

N/A

Waterfalls

Meanders

Oxbow lakes

Floodplain

Mouth

Delta

Tributary: A small river that flows into a larger river

Confluence: The point where two rivers meet

Watershed: the high land that separates two drainage basins

THE UPPER COURSEStages of the River

The Source

• The start of the river

• E.g. This trickle is the start of the River Amazon

Vertical erosion in the upper course of the river. The river is steep and gravity pulls it downhill so it erodes deeply in to the soil. The rocks on the valley sides slide down to make a V shape.

Interlocking SpursLike a zip.

The river erodes deeply in the upper course (vertical erosion) but does not have the energy to erode the harder spurs of rock so it flows around them.

Waterfalls

When a river crosses over a band of harder rock it cannot erode but erodes softer rock underneath. Forms a ledge which will eventually collapse.

MIDDLE COURSEStage of the river

MEANDERS

•Water in a river has slower and faster bits

•This means that there is more erosion on one side than the other

•Water is fastest on the outside edge of the bend so erodes more, it is slower on the inside and so deposits material

•So you get curves and bends in the river

Oxbow lakesWhen meander bends get too tight the water really slows down and too much deposition occurs. Then when a storm happens a new fast channel is eroded straight past the old bend which gets left behind as a lake.

LOWER COURSEStages of the River

FLOODPLAINS

The area of land either side of the river in the lower course that gets flooded.

Very fertile land because of rich soils that get deposited after floods.

Mouth: the end of a river where it flows into a lake or the sea

DELTA:• When the river reaches the sea water slows down rapidly and deposits its material. The load builds up and the river gets broken up into lots of smaller tributaries.

Rivers game

• Noughts and crosses

Hydro song/poem

• Using the textbook and all the keywords, write a song or poem to describe the hydro cycle

• Use pages 66 and 67 to help with terms

Common exam Qs

• These Qs come up often in exams:

- Locate features on diagram of river- Explain the main ways rivers erode- Explain how rivers transport material- Describe and explain how landforms

changed along the course of a river

What features can you tell from a map?

Stages of a River

Upper Stage Middle Stage Lower Stage

Erosion

Gradient

Depth

Velocity

Width

Volume

Landforms