Geography yr 10 EOY -> Rivers

NO CASE STUDY

How does the shape of the valley change at each course of the river?

Upper - V-shaped valley

Middle - slightly more curved + floodplain

Lower - very flat + U-shaped + levees

How does the gradient change at each course of the river?

Upper - source, steep gradient

Middle - gentle gradient

Lower - very gentle gradient → mouth

What is a drainage basin?

An area of land drained by a river and its tributaries

What is the source?

The start of the river

What is a tributary?

A small stream that joins a larger river

What is the confluence?

Where a tributary joins a larger river

What is the watershed?

The edge of the drainage basin

What is the mouth?

The end of a river, usually where a river joins the sea

What is vertical vs lateral erosion

Vertical - downwards

Lateral - sideways

What are the 4 types of erosion?

Hydraulic action

Solution

Attrition

Abrasion

What are the 4 types of transportation?

Traction

Solution

Saltation

Suspension

What is deposition?

Sediment is deposited on the bed and banks of the river and its mouth, where velocity reduces

How are waterfalls formed?

River erodes soft rock underneath hard rock first (undercutting) → hard rock overhang eventually collapses → waterfall retreats

In the plunge pool, pebbles stones and boulders cause erosion

How are gorges formed?

Waterfalls retreating

How are meanders formed?

Erosion on the outer bend end deposition on the inner bend

What is the thalweg?

The fastest current in the river

How are ox-bow lakes formed?

The neck of a meander is gradually eroded → water takes the shortest route + deposition seals off the meander → meander is cut off

What are levees?

Banks on either side of the river caused by flooding + deposition

What are examples of hard engineering + why they are bad?

Dams +reservoirs - expensive+flood risk

Channel straightening - unattractive + unnatural + destroy habitats

Embankments

Flood-relief channels - flooding further down the river

What are examples of soft engineering + why are they bad?

Floodplain zoning - can only be implemented on new builds

River restoration

Preparing for floods - cause insurance premiums to increase