Geography- Rivers

Geography Revision

~ Rivers ~

Definition of Rivers: A river is fresh water flowing over the surface of the land usually to the sea. It flows in a channel.

• Around 97.5% of the world's water is ocean
• Around 2.5% of the world's water is fresh

Key words:

The source: is where the river begins

a Channel: is where a river flows

The mouth: is where a river flows into a lake or the sea

Watershed: is an area of highland forming the edge of a river basin

Tributaries: is a stream or small river flowing in to a main river

The drainage basin: is the area of land drained by a river and its tributaries

Confluence: is the point where 2 rivers join

Advantages:

• transport
• resources (food, water)
• less chance of flooding

Disadvantages:

• May be difficult to cross
• Dangerous (fast flowing rivers, animals)
• Polluted rivers
• Fights over the river
• Flooding

Erosion:- is when the water is removed from the bank and breaks down objects in its way

Hydraulic Action: The water forces air to be trapped and pressured into cracks in the rock on the river bank. The constant pressure eventually causes the rocks to crack and break apart.

Abrasion: The erosion of the river bottom and the river bank by material being carried by the river itself

Attrition/corrasion: The rocks and pebbles being carried by the river crash against each other, wearing down to become smaller, rounded pebbles

Solution/corrosion: The chemical erosion of the rocks of the river bank by the slightly acidic water. This occurs in streams running through rocks such as chalk and limestone.

Transportation:- is the way water is moved from one part of the river to another

Traction: The largest rocks in the river are slowly rolled along the bottom of the river by the force of the water

Suspension: The water carries smaller particles of material

Solution: Materials dissolved within the water and carried along by it

Saltation: Smaller rocks are bounced along the river bed

Deposition:- is when materials are put down or dropped

Rivers deposit when:

• Theres a decrease in speed e.g. at the mouth - meets the sea

• Deposits food onto the flood plain

• Flatter land

and more...