Chapter 2 4.6 Flashcards
What is meant by the long profile of a river
Long Profile means showing the gradient of the river and
how this changes with distance from source
How does the River Eden change along its long profile
The river Eden starts off with the upper course with a small channel shape, a very steep valley profile, with a low amount of gradient, with large sediment size and shape, with a high amount of velocity, low river discharge.
The middle course has a medium channel shape, no valley profile, a medium gradient, medium amount of discharge, medium amount of velocity, medium size and shaped of sediment.
In the lower course there is high river discharge, a wide channel shape, no valley profile, low gradient, high velocity, low sediment size and shape.
What are the reasons for these changes?
The main reasons these changes are happening are vertical erosion which is the deepening the river valley (and the channel), making the river valley v-shaped. As well as lateral erosion, this widens the river valley and channel, it mainly occurs in the middle and lower courses.
Define weathering
Weathering breaks down rocks especially on the valley sides, e.g. freeze-thaw weathering breaks down rock when the temperature alternates above and below 0°C, (the freezing point of water).
Compare hydraulic action with abrasion
Hydraulic action is just the force of water acting alone to break up the rock were as abrasion is were the the water picks up the rocks and carries them to the river channel wearing them away. Also, abrasion occurs more than hydraulic action.
Compare traction with suspension transport
With traction large rocks like boulders have to pushed along the river bed by the force of the water, whereas small particles like silt and clay are carried along by the water, this is called suspension.
Compare a flashy and subdued hydrograph
A flashy hydrograph would have a large amount of rainfall in a short amount of time compared to a subdued hydrograph which would have still have a large amount of rainfall but in a longer period of time. The flashy hydrograph would also have a smaller lag time than the subdued hydrograph. The fla
Explain two ways climate, geology and slope processes change the river landscape
All of the things above can influence the upper course landscape such as v-shaped valleys because the climate brings weather patterns on it and then the weather acts on the geology of the rock and the slope processes carry the scree away. They can also influence the shape of the river in the upper course the scree from the weathering processes got deposited there and this can block the path of the water.
Compare freeze thaw and biological weathering
Biological weathering is the breakdown of the rock by living things e.g. plant roots. On the other hand, freeze thaw weathering happens when the temperature alternates above and below 0°C (the freezing point of water). The plant roots begin to break down the rocks by growing into cracks on their surface and pushing them apart. The freeze thaw weathering also really acts quickly when the water is below 0°C because this puts pressure on the rock, when the water thaws it releases this pressure. Repeated freezing and thawing widens the cracks and eventually leads to parts of the rock breaking up. In conclusion, biological weathering uses plants to break up rock were as freeze thaw weathering uses pressure on the rocks to break them up.
Explain how physical factors (geology, soil, slope, basin type, antecedent conditions) can affect flood hydrographs.
Geology can affect the flood hydrographs because the rocks can be impermeable and not let any water get into them creating surface run off.
Soil can also create surface run off from too much saturation
Slopes can also affect hydrographs as water can only go down the slope making a large amount of potential flood water.
If the basin has a semi circular shape then the water would just build up in the middle of it and there would be a flashy hydrograph.
