Rivers

• Attrition - material is moved along the river bed, collides with other material and breaks into smaller pieces.

• Abrasion - fine material rubs against the river bank, the bank is worn away by a sandpapering action.

• Solution - rocks from the banks and the river bed are dissolved by acids in the river.

• Hydraulic action - the sheer force of the water hitting the river banks.

• Traction - large rocks are rolled along the river bed.

• Saltation - smaller stones are bounced along the river bed.

• Suspension - small grains of sand are carried in the water.

• Solution - material is dissolved and carried downstream.

The Finer --> The Fragments --> The Futher --> They Flow.

Deposition occurs when a river can no longer support material.

Material is put down when the river no longer has the energy to carry the load.

• Watershed - a boundary that separates drainage basins.

• Main channel - the main river.

• Confluence - Where the tributary meets with the main channel.

• Tributary - a small stream flowing into the main channel.

• Mouth - where the river meets the sea.

• Slope/relief - the steeper the slopes, the faster the runoff, so more water in the river.
• Rock type - impermeable rock will mean a surface runoff.
• Soil - thin soil, less infiltration. Deeper soil, more infiltration.
• Land use - rural areas with little tarmac/concrete or drains there will be a higher level of infiltration.
• Precipitation - more intense rain, the shorter the lag time/more rain in the river.
• Temperature - in the summer, dry soil, longer lag time as rain infiltrates. In the winter, frozen or saturated soil, shorter lag time as water cannot infiltrate so runs off quickly.
• Previous weather - large amounts of rain, saturated soil, cannot allow any more infiltration so run-off increases.

• Dams and Reservoirs - used to save/manage the flow of excess water. Some are used to generate hydropower.

• Man-made Levees - stop water flooding over. Commonly used in rivers near the sea.

• Straightening Meanders - Involves digging a shorter channel. This can cause flooding downstream.

• Dredging Channels - Can allow importing and exporting. But can cause a mess in the sea traffic.

• Do nothing - The natural habitat is left, doesn't interfere with the rivers flow, it's cheaper to maintain.

• Flood warnings and preparation - Buildings will be saved and people will be prepared. However unexpected floods will mean the equipment won't be available.

• Floodplain zoning - Identifies areas of varying flood hazards.

• Re-afforestation/plant tree - Replacing of forests and woodlands that have been destroyed. Trees intercept the rain and slow down the run-off to the river.