AS River Environments

What processes and factors are resposible for distinctive fluvial landforms?

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  • Created on: 14-04-13 20:16
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River Environments
What processes and factors are responsible for distinctive fluvial
Slope Processes
Slopes are defined as any part of the solid land surface where there is an incline. Processes
operating on slopes have a major impact on fluvial landscapes. Slope processes transfer
material downslope to the river.
Slow Movements
Soil creep
Individual soil particles are pushed or heaved to the surface by wetting or freezing of water.
Terracettes are created, these are small terraces from a few centimeters to 0.5m across
the face of a slope caused by soil creep or solifluction.
Rain-splash erosion
This is when individual raindrops compact the soil and dislodge particles equally in all
directions. In contract in some case solifluction takes place. The term solifluction literally
means `flowing soil' and if effected by freezing and thawing in cold periglacial environments.
Flow Movements
Surface Wash
This occurs when the soil's infiltration capacity is exceeded and can lead to the formation of
Sheetwash is the unchannelled flow of water over a soil surface. ON most slpes sheetwash is
divided into areas of high velocity separated by areas of lower velocity.
Through Flow
Through flow is water moving down through the soil. It is channeled din to natural pipes in the
soil. This gives it sufficient energy to transport material.
Fast Mass Movements

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Sliding material maintains its shape and cohesion until it impacts at the bottom of a slope
and leads to large, slumped terraces.
Rock falls occur on steep slopes. The initial cause of the fall may be weathering, for example
Slumps occur when weaker rocks especially clay, and have a rotational movement along a
curved slip plane. Clay absorbs water, and becomes saturated, and exceeds its liquid limit. It
then flows along the slip plane.…read more

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Rate of weathering varies with climate. Peltier's diagram shows how weathering is related to
moisture availability and average annual temperature. Frost shattering increases as the
number of freeze-thaw cycles increase. Chemical weathering increases with moisture and
Rock type influences the rate and type of weathering in many ways due to:
Chemical composition
The nature of cements in sedimentary rock
Joints and bedding planes.…read more

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There are a number of types of erosion on a river, these include:
Hydraulic action
There are also a number of factors affecting the rate of erosion, these include:
Human impact.
Deposition occurs when a river loses energy.…read more

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