Physical landscapes (Incl. Rivers) Flashcards
1
Q
What is interception?
A
The process of storing water, possibly through vegetation.
2
Q
What is infiltration?
A
When vegetation catches water and stores it.
3
Q
What is percolation?
A
When water flows from the soil moisture to the ground water.
4
Q
What is surface runoff?
A
The flow of water as water travels from surface to river.
5
Q
What is throughflow?
A
The flow of water from soil to river.
6
Q
What is groundwater flow?
A
Water that travels through the ground back to the river.
7
Q
How was the UK landscape been created?
A
It has been created over millions of years by the action of water, wind and ice through the processes of erosion, transportation and deposition.
8
Q
What is the pattern relating relief of land and population?
+ Give examples of places and include numbers.
A
- Areas that have a low relief (e.g. Manchester, London) are more densely populated with over 250 people per square kilometre.
- However, places with a higher relief (e.g north Scotland) are much less densely populated with under 50 people per square kilometre.
9
Q
How do high UK landscapes affect peoples’ lifestyles?
A
The high ground nay cause surplus in supplies such as water, but also may have limited access to things like food as it is more difficult to transport / find somewhere to sell it.
10
Q
What advantages and disadvantages might low landcapes like London have?
A
- They might have an advantage in areas such as transport as its easier to build roads on flat land.
- But, water may be more difficult to obtain as extensive water transfer schemes have to be used which can easily go wrong.
11
Q
What is a drainage basin?
A
The land that is drained by a river and its tributaries. It contains different flows of water, including input and output.
12
Q
Define the source.
A
Where a river starts, usually in the mountains.
13
Q
Define the mouth.
A
Where a river ends, at a lake or the sea.
14
Q
Define tributary.
A
A smaller river that joins a larger one.
15
Q
Define confluence.
A
The point at which rivers meet.
16
Q
Define watershed.
A
The highland separating one river basin from another.
17
Q
Define drainage basin.
A
The land that is drained by a river and its tributaries.
18
Q
Define input.
A
The addition of water into a drainage basin.
19
Q
Define flows / transfers.
A
The process by which water moves from one point to another.
20
Q
Define storage.
A
Where water is held for a period of time.
21
Q
Define output.
A
The loss of water from the drainage basin.
22
Q
What does the long profile of a river show?
A
The long profile shows how a river’s height above sea level changes from its source to its mouth. it is plotted as a line graph.
23
Q
What happens in the upper course of a river?
A
The river starts high above sea level. The gradient is very steep and the height quickly drops.
24
Q
What happens in the middle course of a river?
A
The gradient is gentler and the height drops more slowly.
25
What happens in the lower course of a river?
The gradient is at its gentlest and the height of the river above sea level drops at its slowest reaching sea level at the mouth.
26
What is a valley profile?
A cross section view across the whole river valley from one side to the other. The river channel itself sits in the bottom of the valley.
27
What happens to the cross profile in the upper course?
In the upper course, the cross profile is narrow. The valley is relatively deep. It is V shaped with steep valley sides. The river occupies the whole valley floor.
28
What happens to the cross profile in the middle course?
In the middle course, the cross profile is wider and the river no longer occupies the whole valley floor. It meanders around in the flatter valley bottom. The valley is less deep and the valley sides are less steep and further from the river. the valley is more U shaped.
29
What happens to the cross profile in the lower course?
In the lower course, the valley is a its widest with a low lying valley floor. The valley sides are a long way from the river channel and are much gentler. The valley is a very broad U shape.
30
Which part of the river does the most erosion usually occur?
The upper course.
31
Define abrasion.
Rocks carries along by the river wear down the river bed and banks. This has a sandpaper effect causing lateral and vertical erosion.
32
Define lateral erosion and where it usually occurs.
Sideways erosion by a river.
-> Mostly in the middle and lower course.
33
Define attrition.
Rocks being carried by the river smash together and break into smaller, smoother and rounder particles. The river load therefore gets smoother, smaller and rounder as you get closer to the mouth.
34
Define solution.
Soluble particles of rock are dissolved into the river. This only happens with certain, soluble rocks when they react with river water.
35
Define vertical erosion and where it usually occurs.
Downward erosion of a river bed.
-> Mostly in the upper and middle courses.
36
Define hydraulic action.
The force of the river against the banks can cause air to be trapped in cracks and crevices. The pressure weakens the banks and gradually wears it away.
37
Define traction and where it usually happens.
The rolling of large boulders and pebbles along the river bed. Usually happens in the upper course.
-> Heavy bits only move when the river has high levels of energy.
38
Define saltation and where and how it usually happens.
Smaller pebbles are bounced along the river bed in a leap-frog movement. This usually happens in the middle course. When 1 particle lands it sets off more. This usually happens when the river's energy level is high.
39
Define suspension, where it happens and an example using materials.
When very small and lightweight particles are carried in the water flow. This is common in the ower course.
-> E.g silt and clay - this can happen even at really low water speeds - it doesn't need much energy.
40
Define solution.
When dissolved particles of rock are carried by the river (invisible). Soluble rocks include chalk and limestone.
41
What is deposition?
When rivers drop or deposit the river's load, usually in the lower course.
42
When does deposition happen?
- The river moves more slowly (the velocity decreases).
- This means that the river loses energy.
- This might happen where the gradient of the river reduces, for example, when the river flows into a lake or the sea.
43
What order does deposition occur?
The heaviest particles are dropped first, so they don't travel very far. Then the next heaviest and so on until only the very lightest and smallest particles remain - these can travel the furthest distance downstream.
44
How do waterfalls form?
- They form in the upper course.
- As water flows over the hard rock on top and soft rock under, it erodes the softer rock, causing an undercut by the erosion of hydraulic action and abrasion.
- As the water hits the bottom of the floor with great force, a plunge pool is created, which then gradually gets bigger as more erosion happens.
- The undercut also becomes weaker as it erodes more, so it collapses, meaning the waterfall is constantly being pushed back, leaving behind a steep sided valley called a gorge.
45
How are interlocking spurs formed?
- vertical erosion as the river is trying to reach sea level
- the valley sides are prone to weathering such as freeze thaw, which can cause them to collapse
- the deposit is carried away by the river leaving a v-shaped valley
- the upper course has little energy and can’t erode the hard rock so it takes the easiest route, winding round obstacles
- this leaves a zig-zag sort of pattern from above
46
How does a meander / ox bow lake form?
- water travels at different speeds: slower in shallower areas and faster in deeper areas
- this causes the fastest current to move around obstacles in a winding motion
- the fast water has lots of energy so begins to erode at the banks of the river causing the channel to bend
- where there is a slower channel, deposition occurs
- abrasion and hydraulic action continue on the outside bend creating a river cliff
47
How are floodplains and levees formed?
- during a flood, the river discharge is so high that the river can’t hold all the water so the banks burst
- water slows down as it leaves the channel and therefore loses energy and deposits the load
- deposited material is sorted, the courser, heavier material closest to the bank and the finer sediment further away
- after many floods, the banks build up to form levees with layers of material and the floodwaters recede, leaving a layer of alluvium across the flood plain
48
What is a flood plain?
the relatively flat area of land on either side of a river channel forming the valley floor.
49
What marks the edges of the floodplain?
Bluffs.
50
What is an estuary?
where a river meets an ocean and is affected by the tide so saltwater mixes with freshwater.
51
How are estuaries formed?
- the land is at sea level and uses its energy for lateral erosion so estuaries are very wide.
- freshwater mixes with the saltwater from the sea.
- at high tide, the water level rises and the river slows down as the water trying to get out competes with the water trying to get in.
- this causes a reduction in the river’s velocity and the energy levels drop, causing deposition.
- the material being transported is mostly very fine
- the alluvium mixes with the sand and silt and muddy sediment is.
52
What is river flooding?
when there’s too much river to be contained so it overflows onto the floodplain.
53
What are physical features that lead to flooding?
- precipitation
- geology
- relief
54
What are the human factors that lead to flooding?
- deforestation
- urbanistation
55
What is discharge?
the amount of water flowing through a river at any one time.
56
What is CUMECs and how is it calculated?
the amount of discharge and it calculated by the cross sectional area x velocity.
57
What is the lag time?
the time between peak rainfall and peak discharge.
58
What is the discharge line?
the amount of water in a river.
59
What is a flashy hydrograph?
a hydrograph that peaks earlier on and curves upwards and has a high peak discharge and short lag time.
60
When might you have a flashy hydrograph?
- where there’s deforestation
- steep-sided valleys
- lots of surface streams
- urban areas
- rain for prolonged periods of time
- prolonged, heavy rainfall
- temperatures above freezing causing snow to melt
- concrete and artificial channels.
61
What is a subdued hydrograph?
a hydrograph that remains fairly steady and has a low peak discharge and long lag time.
62
When might you have a subdued hydrograph?
- in forested areas
- gently sloping land
- few surface streams
- rural areas
- dry and hot (unless too hot and land can’t absorb water)
- gentle showers
- snow and below 0 degrees
- dams and reservoirs
63
What is hard engineering?
artificial, man made structures to prevent flooding.
64
What is soft engineering?
using natural environments to prevent flooding.
65
What are the benefits in river management?
Financial savings made by preventing flooding along with any environmental improvements.
66
What are the costs in river management?
the financial cost of the scheme, and any negative impacts on the environments and people’s lives.
67
What are hard engineering methods to prevent flooding?
- dams and resevoirs
- channel straightening
- embankments
- flood relief channels
68
What are soft engineering methods to prevent flooding?
- flood warnings and preparation
- flood plain zoning
- planting trees
- river restoration
69
Why does the River Tees need managing?
- high relief land
- high levels of precipitation (2,000mm/yr)
- impermeable rocks
- flashy hydrographs
- 400 year history of flooding
- lots of properties at risk including 12 schools, 8500 homes and 1200 commercial properties
- 687,000 residents nearby
70
How is flooding on the River Tees managed?
- Cow Green reservoir
- Tees Barrage
- Flood defence scheme in Yarm
- Dredging
- Cutting of meanders
71
What is the Cow Green reservoir and what are the social, environmental and economic benefits?
built in 1970 to protect against flooding - regulating reservoir
s - bronze age farming discovered and studied
ec - less cost effective than it used to be and still needs other flood relief measures
en - increased population of brown trout but concerns over protection of rare plant species
72
What is the Tees Barrage and what are the social, economic and environmental benefits?
man made barrier across the river with aims to improve water quality and recreational value and was completed in 1995
s - £500m towards leisure activities and housing
en - reduces flood risk but doesn’t mix with tidal salt water
ec - cost £54m but was a catalyst for £500m of investments
73
What is dredging and what are the social, economic and environmental benefits?
sediment is removed in lower parts of the Tees estuary periodically to improve navigation
s - increased capacity protects schools and businesses from flooding
en - sediment removed reduces flood risk
ec - can be expensive
74
What is the cutting of meanders and what are the social, economic and environmental benefits?
in 1810, Tees Navigation Company cut across the neck of the Mandale Loop, shortening the river by 4km
s - faster channel protects schools and businesses from flooding
en - reduced flood risk due to faster channel
ec - allows more trade as ships can navigate around the river
75
What are the flood defence schemes in Yarm and what are the social, economic and environmental benefits?
after the 1995 flood, a new defence scheme was put in place costing £2.1mil including things such as putting in concerete with metal flood gates, earth embankments and gabions
s - land is used for leisure areas such as playing fields and parks
en - gabions helped reduce erosion
ec - made the area look nicer and more attractive, making more people want to go there
