RIVER TRANSPORT

A river carries or transports eroded materials such as mud, sand, boulders and dissolved materials on its journey.

These materials are known as its load.

The load is carried along by four processes

1.Traction– large boulder rolled and slided along the river bed.

2.Saltation– small stones and pebbles bounced along the river bed.

3.Suspension-light and fine rocks is carried along by the river

4.Solution-minerals are dissolved in water.

River Transport

River Landform- EROSION

Potholes
Potholes are holes in the river bed.
They vary in size from a few centimetres to several metres in diameter.
Potholes are formed by corrasion.
Pebbles carried by the river are swirled around on the river bed. This action erodes the rock on the river bed forming potholes.
Over time, they may widen and join with other potholes to form larger potholes, and the whole river bed is deepened.
Potholes
Rapids
Rapids are stretches of fast-flowing water tumbling over a rocky-shallow riverbed.
Different resistance among rocks cause rapids.
They are formed when the water goes from one hard rock that resists the water’s erosion to a softer rock that is easier eroded.
As result, the rapids form a series of steps.
Rapids

The Rapids

Waterfalls
Waterfalls occur when a band of hard rock lies across the river with softer rock downstream which is more rapidly eroded.
At first rapids would form but then develop into a waterfall as the softer rock erodes further.
Variations may be caused by the rock structure.
The formation of waterfalls have two ways;
Waterfalls (vertical) formation
The river erodes the less resistant rock more rapidly and this result in a change in the gradient.

The vertical waterfalls

Waterfalls (horizontal) formation
A waterfall is formed where there is the sudden fall in height. The river plunges and hits the bottom of the river bed with great force.
Rocks are swirled around to form a deep pool at the river bed known as a plunge pool

Waterfall Horizontal formation

Gorges
Gorges are formed when rivers erode vertically through resistant rocks.
Since these rocks are not easily erode , the sides of the valley remain steep.
Gorges is a deep valley, narrow and steep sided.

The Gorges

RIVER EROSION

River Erosion is the river erodes away the bed and banks of its channel vertically and laterally.
Vertical erosion is the downward erosion which deepens the river channel
Lateral erosion is sideward erosion which widens the river channel

The vertical and lateral erosion

There are four ways how the river erode the bed and the bank( EROSIONAL PROCESS)
1. Hydraulic action– the force of river flow helps to break the rock and dragging them away from the bed and the banks of the river.
2. Corrasion/abrasion– the grinding of the rock fragments carried by the river against the banks and bed of the channel. This grinding action will widens and deepens the channel.

Corrasion

3. Attrition– the knocking of rock fragments in the water against each other. The fragments are broken into smaller and become smoother pebbles.

Attrition

4. Solution/corrosion– the process of the water reacts chemically with soluble minerals in the rocks and dissolve them.