Paper 2 (UK): Topic 4 EQ4-4.6 – Landscapes and processes Flashcards
What is meant by the long profile of a river?
The long profile of a river shows changes in the height (altitude) of the course of a river from its source to its mouth. A long profile is usually concave and the slope becomes more gentle towards the mouth of the river.
How does the river Eden’s landscape change along its long profile
(upper/middle/lower). Consider: channel shape, valley profile, gradient, discharge, velocity and sediment size and shape?
Along the upper course of the river eden the river would be at a increased gradient and the river would generally be flowing slower and down to the middle course of the river it would be a little larger but not too big and the velocity of the water would be a little bit faster due to there being more mass of water and the river discharge would be more. Towards the bottom of the river there would be a larger and increased area of the river, the river discharge would be a lot greater however there would be smaller sediment within the river with a larger velocity of the water flowing in the lower courses.
What are the reasons for these changes?
These changes could be due to the change in altitude and the change in the amount of rain and amount of water that comes down from the river source changing the sediment size and river discharge within the river.
Compare hydraulic action with abrasion
Hydraulic action is where the force of the water breaks rock particles away from the river channel. Abrasion is where eroded rocks picked up by the river scrape and rub against the channel, wearing it away. Most erosion happens by abrasion
Define weathering
Weathering is the breakdown of rocks where they are and erosion is when the rocks are broken down and carried away by something, e.g. by seawater. There are three types of weathering: mechanical, chemical or biological weathering.
Compare freeze thaw and biological weathering
Freeze thaw weathering happens when the temperature alternates above and below 0°C (the freezing point of water). Water gets into rock that has cracks, e.g. granite. When the water freezes it expands, which puts pressure on the rock. When the water thaws it contracts, which releases the pressure on the rock. Repeated freezing and thawing widens the cracks and causes the rock to break up. Freeze thaw weathering is a type of mechanical weathering. Biological weathering is the breakdown of rock by living things, e.g. plant roots break down rocks by growing into cracks on the surface and pushing them apart.
Compare traction with suspension transport
Traction is where sediment is pulled along the bed of the river whereas suspension transport is where the sediment is small and light enough to be moved along the surface of the water and transported along the rivers courses and downstream towards the place where the sediment will rest.
Explain the stages and processes responsible for waterfall formation, v shaped valleys and interlocking spurs, meanders, ox-bow lakes, flood plains, levees and deltas. Do each of these in turn – this is a big question!
Waterfalls are formed when rivers move from a hard rock to a soft rock, this happens when the rock which is soft breaks and erodes downwards, after this the waterfall would carry on the process and retreat backwards along the river forming a gorge, V shaped valleys are formed by rivers when the river runs through the valley and the valley would be eroded into a V shape. Interlocking spurs are mixes between hard rock and soft rock, when this happens a river runs around the hard rock to form the spurs within the river. Ox-bow lakes are formed when a river meander becomes so large that it can no longer flow and cuts through to form the new river, the old part of the river would form to become the oxbow lake. Flood plains are formed when a river overflows and the discharge of the river would overflow onto the flood plain, this is the area where it is most likely to flood. A levee is an embankment on a river which would stop water from flooding within a river. A delta is where a river deposits sediment so that the water creates land around the river.
Explain two ways climate, geology and slope processes change the river landscape
The climate could change the river landscape as it changes where the water molecules may be expanding or get smaller which could affect the amount the river floods and the floodplains increase in size. The slope processes changes the landscape from being flat, to a valley all the way to waterfalls and gorges which are all formed this way.
Label the key features (lag time, rising limb and peak discharge) of a flood hydrograph
On goodnotes
Compare a flashy and subdued hydrograph
A flashy hydrograph is different to a subdued hydrograph, this is because a flashy hydrograph would show a flood coming in a short period of time whereas a subdued hydrograph show us a flood which may be greater but over a longer period of time making it seem even worse.
Explain how physical factors (geology, soil, slope, basin type,
antecedent conditions) can affect flood hydrographs.
A physical factor such as the type of basin and how large it is would affect the flood hydrograph as if it is a larger basin then more water would enter the flood plain, the soil type may also affect the flood hydrograph as a more solid soil type may allow less water to permeate through the ground therefore causing more surface run off and larger flood risk.
