Water Flashcards
0
Q
Watershed
A
The highland separating one river basin from another
1
Q
V-shaped valley
A
Are usually found in the mountains and hills. They often have very steep sides
2
Q
Mouth
A
The end of the river. The mouth may be where the river meets the sea, a lake or a
A large water way. Most rivers flow into the sea and this is where they end their journey
3
Q
Ox-bow lake
A
A small arc shaped lake formed when a meander is sealed off by decomposition. Ox-bow lakes are only found on liver flood plains
4
Q
Meander
A
A bend in a river
Usually in the middle or lower course
5
Q
Tributary
A
A stream or river that flows into and joins a main river
6
Q
Confluence
A
Where two rivers or streams meet
7
Q
Erosion
A
The degradation and removal of rock material by the river
8
Q
Abrasion
A
Degradation of the river bed through the scouring action of materials being being carried by the river
9
Q
Hydraulic action
A
Form of mechanical weathering caused by the force of moving water currents rushing into a crack
10
Q
Attrition
A
A process of erosion where the collisions between parts of the load lead to them breaking down
11
Q
Corrosion (solution)
A
Soluble particles such as carbonates like limestone and chalk are dissolved into the river by weak acids in the water and are then carried away down the river
12
Q
Transport
A
The movement of sediment load by water
13
Q
Load
A
Any material that is in the river
14
Q
Traction (bed load)
A
The rolling of load along the bed of a river channel
15
Q
Saltation
A
The transport of load by bouncing along the bed of a river channel
16
Q
Suspension (suspended load)
A
The transport of load in the body of water in a river. I.e being carried along in the flow
17
Q
Solution
A
Minerals are dissolved from soil or rocks and carried along in the flow
18
Q
Deposition
A
When a river loses energy it will drop or deposit some of the material it is carrying
19
Q
Drainage basin
A
An area of land drained by a river and its tributaries
20
Q
What does vertical erosion cause and where and why does it happen?
A
Happens in rivers in the mountains as they flows down steep slopes.
Vertical erosion causes a v shaped valley
21
Q
How are interlocking Spurs made?
A
When the river winds around obstacles of hard rock
22
Q
When does a waterfall occur?
A
- river flows over different rock types
- river erodes soft rock faster creating a step
- further hydraulic action and abrasion form a plunge pool beneath
- hard rock above is undercut leaving an unstable top of hard rock
which collapses providing more material for abrasion - process continues - waterfall retreats leaving a steep sided gorge
23
Q
Precipitation
A
Moisture falling from clouds as rain, snow or hail
24
Surface run off
Water flowing over the surface of land into a river
25
Evaporation
Water lost to the atmosphere as water vapour
26
Transpiration
Water lost through stoma in leaves of plants
27
Groundwater flow
Water flowing through deep underlying the rocks
28
Through flow
Water flowing through the soil layer into a river
29
Infiltration
Water absorbed into the soil from the ground
30
What increases surface runoff?
Relief- steep slopes. Water runs straight over land
Rocks- nonpermeable rocks don't allow infiltration so there is surface runoff
Roads- impermeable. Can't soak up water
Deforestation- less trees to soak up water. Ground saturates faster
Cattle- trample soil. Compact it so less water infiltrates
31
CASE STUDY- water fall MEDC
NIAGARA FALLS - border between Canada and USA
Tourism- boat rides, souvenir shops, restaurants etc. More money in area. Negatives- pollution, disturb animals, attracts pests (pigeons)
Hydroelectric plant- produces lots of energy- one of the worlds greatest sources of hydroelectric power, low cost energy
32
What are some causes of flooding
Loss of trees
Heavy rain
Lots of tributaries
Impermeable rock
Built up areas - concrete
Steep slopes
33
What are some effects of flooding
Loss of jobs
Loss of properties
Damage to home and business
People and animals killed or injured
Spread of disease
Disruption to motorway and rail networks
Flood defences damaged
34
What are some responses to flooding?
Demolition of property which is unstable
Improve drainage systems
Repair or build flood defences
Increase and update flood warning systems
Create new water diversions
35
CASE STUDY - waterfall LEDC
SIPI FALLS - Eastern Uganda, near Mt Elgon
major tourist destination
Tourism- campsites , lodges, hiking, climbing etc
creates money and jobs
tourists can be disrespectful, scare animals- birds
36
Hard engineering techniques
Building up of levees (artificial levees)- heightens river so flood water is contained
Dams- control amount of discharge
Straightening the channel- increases velocity to remove flood water
Deepening or widening channel- increases the river's capacity
37
Soft engineering techniques
Do nothing- river is left to flood
Flood surrounding farmland- saves the flooding of urban areas
Afforestation- plant trees, soak up flood water
38
CASE STUDY- flooding MEDC
BOSCASTLE FLOODS - 2004
North coast of Cornwall
Causes-- situated in a valley, stormy weather- ground was saturated, lack of flood control systems, old drainage system
Short term impacts-- Property destroyed, 80 cars washed away, burst sewage mains, roads blocked with flood water- made emergency access difficult.
Long term impacts- Home insurance more expensive, town closed to tourists- loss in revenue
39
CASE STUDY- managing rivers
Three gorges dam - China, River Yangtze
Costed $30 billion
Dam in upper valley stores water and controls flow
causes landslides and seismic activity
1.2 million people forced to relocate
SIGNIFICANTLY REDUCED RISK OF FLOODING
40
CASE STUDY- LEDC flooding
BANGLADESH - south Asia
Causes-- delta, low land, monsoon season, snow melt from Himalayas, deforestation, global warming
Long term impacts- 100,000 suffering with diarrhoea
Short term impacts- 750 deaths, 30 million homeless, rice and sugar crops washed away
Responses-- charities sent boats, food, aid, rebuilding of homes , embankments built along the river, some flood warning systems
41
Should we change our approach to river and flood plain management in the future?
Global warming- increasing number of people at risk
Flood risk made worst as town are built close to rivers- In future don't build on flood plains
Use soft engineering to return river to natural state
Don't pave over gardens- impermeable.
Make home more flood proof
build more flood defences and flood warning systems
42
Describe the formation of a meander
Inner bend- low energy - deposition of sediment- creates a slip off slope. There is a slow current
Outer bend- high energy encourages erosion- abrasion. Steep rive bank. There is a fast current
43
Describe the formation of an oxbow lake
1- Lateral erosion of outer bank forms a river cliff. Deposition on inner bank forms a slip off slope
2- due to further hydraulic action and abrasion of outer banks, neck gets smaller.
3- erosion breaks through the neck so the river takes the fastest route, redirecting the flow
4- evaporation and deposition cut off from main channel leaving an oxbow lake.
44
What land forms and features do you find in the upper course of the river?
v shaped valleys
narrow/shallow channel
interlocking spurs
waterfalls
gorges
45
What land forms and features do you find in the middle course of the river?
open/gentle sloping valley
floodplain
wider/deeper channel
more suspended sediment
meanders/ox bow lakes
river cliffs
slip off slopes
46
What land forms and features do you find in the lower course of the river?
open/gentle sloping valley
flat and wide floodplain
wide, open valley
very wide and deep channel
levees
47
Describe how deltas are formed
caused by deposition at the mouth of the river
When river enters the sea, it loses its energy and can no longer carry so much material. Its load is deposited.
If this happens faster than the sea can carry it away, a delta forms
48
Why do some people chose to live on or near deltas?
They provide rich land for farming
49
What are the 3 types of delta?
arcuate
cuspate
birds foot
50
Describe how levees are formed
levees are natural embankments formed when the river floods
when a river floods, it deposits its load over the floodplain due to a dramatic drop in the rivers velocity
51
Describe the formation of floodplains
as river nears its mouth, it has a large discharge.
Each time the river floods, silt is deposited on the floodplain
52
What factors increase surface run off?
relief- steep slope- water runs straight off land
Rocks- non permeable- do not allow infiltration
Farming- ploughing up and down hills forms channels
roads- impermeable- water straight in drains
Trees- deforestation- ground saturates faster
cattle- trample soil, compacts it so less water infiltrates
machinery- compacts soil- less infiltration
53
What does a hydrograph show?
The river discharge over a period of time
54
On a hydrograph, what is the lag time?
The time between peak rain fall and discharge
55
On a hydrograph, what does a rising limb show?
the rising flood water into the river
56
On a hydrograph, what does the falling limb show?
The declining flood water
57
On a hydrograph, what does the base flow show?
the normal discharge of the river
58
Definition of soft engineering
works with the environment
59
Definition of hard engineering
Uses machinery or defences constructed by people to control natural processes
60
What are some advantages and disadvantages of using soft engineering techniques
environmentally good, cheaper
farmland easily lost, could take a long time for maximum effect (afforestation)
61
What are some advantages and disadvantages of hard engineering techniques
last a long time, people feel safe
expensive, ugly, unnatural
62
What are some soft engineering techniques to manage a river?
afforestation
flood surrounding farmland- saves flooding of urban areas
do nothing
63
What are some hard engineering techniques to manage a river?
straightening the channel- increases velocity to remove flood water
artificial levees- heightens river so flood water is contained
deepening or widening the channel- increases river's capacity
dams- control river discharge
64
Explain how river land forms affect the lives of people who live along rivers
Floodplains- provides ideal land for farming (fertile soils) -eg Bangladesh- and building (flat surface). However flooding can affect farm yield. Therefore buildings and farms need to be protected
Waterfalls- eg Niagara Falls- tourist attraction, provides employment however negatives- attract pests as tourists leave litter
65
Explain how a slip off slope is formed
there is a slower flow of the river as the river has less energy to transport material
this causes the material to be deposited. Large stones are deposited first and then smaller ones
