Book Creator

Higher Hydrosphere

by Mr Bell


Physical Environments 3

1. Formation of erosional and depositional features in river landscapes:

— V shaped valley
— waterfall
— meander
— oxbow lake

2. Hydrological cycle within a drainage basin

3. Interpretation of hydrographs
1. Formation of erosional and depositional features in river landscapes:
River Features
A typical river process can be split into 3 sections, Upper, Middle & Lower courses.

As the river flows downstream much of the energy is used up overcoming friction from the riverbed & banks.

Energy comes from the volume & velocity (speed) of the river. 
Traction - quite large stones can be rolled or dragged along the riverbed by the force of the water.

Saltation - small stones which the water cannot lift, bounce off each other and are carried forward for short distances by the water above the riverbed.

Suspension - if particles are small enough the river can lift them and carry them long distances.
Solution - when the river dissolves minerals from the rocks they are carried in the water itself.
Processes of Erosion
Hydraulic action which is when air is compressed into the riverbank (1) causing materials to be dislodged (1)

Abrasion when the force of the water (1) throws bedload against the banks causing erosion (1)

Attrition when rocks & boulders collide and break up (1) these smaller pieces can aid with abrasion (1).
Solution when the river water dissolves minerals from the rocks (1) and washes them away (1). 
This occurs where the river looses the surplus energy it requires to transport material and it is deposited. This can occur due to:

•Rivers reach a sea or loch
•Rivers overflow their banks
•On the inside of a river bend
•Flood water subsiding or drought
•Sudden decrease in gradient (plunge pool)

When this happens the river will deposit the heaviest material first and transport lighter material (load) further. In this way the load is sorted by weight.