RIVERS

Question 1

What is a drainage basin?

Answer 1

The area surrounding the river where the rain is falling on the land that flows into the river, also known as the catchment. The boundary of two drainage basins is called the watershed. They are open systems with inputs and outputs.

Question 2

What are the inputs to the drainage basin?

Answer 2

Precipitation, including all the ways moisture comes out of the atmosphere – rain, snow, hail, dew and frost

Question 3

What are the stores in a drainage basin?

5

Answer 3

Interception – when precipitation lands on vegetation or other structures before it reaches the soil, this causes a significant store in woodlands
Vegetation storage – water taken up by plants
Surface storage – puddles, ponds and lakes
Groundwater storage – stored in the ground either in soil or rocks, porous rocks that hold water are called aquifers. The water table is the top surface of the zone of saturation.
Channel storage – water held in a river of stream channel

Question 4

What are the flows in the drainage basin?

10

Answer 4

Surface runoff – water flowing overland, common in arid areas where torrential rain falls on hard baked land
Through fall – water dripping from one leaf to another
Stem flow – water running down a plant stem or tree trunk
Throughflow – water moving slowly downhill through the soil, faster through pipes like crack or animal burrows
Infiltration – water soaking into the soil, rates are influenced by soil type, soil structure and how much water is already in the soil.
Percolation – water seeping down through the soil into the water table
Groundwater flow – water flowing slowly below the water table through permeable rock.
Base flow – groundwater flow that feeds into rivers through banks and river beds
Interflow – water flowing downhill through permeable rock above the water table
Channel flow – water flowing into the river or stream – also called river discharge.

Question 5

What are the outputs of the drainage basin?

4

Answer 5

Evaporation – water turning from a liquid to gas
Transpiration – evaporation from plant leaves from water taken up through roots
Evapotranspiration – process of evaporation and transpiration together
River discharge, river flow

Question 6

What is the water balance?

Answer 6

It shows the difference between the inputs and outputs in a drainage system.
When there is more inputs, precipitation, the soil moisture is either in recharge after a period of evapotranspiration or in surplus. In periods where there is lots of evapotranspiration the soil moisture is in utilisation and then deficit.

Question 7

What are the factors affecting river discharge and the storm hydrograph? (6)

Answer 7

Characteristics of the drainage basin
- Size of basin, how much precipitation can be caught and distance water has to travel into channel
- Gradient of slopes
- Circular basins have watersheds roughly at the same distance from the point where discharge is measure, lots of water will reach this point at the same time
Antecedent condition
- If the ground is waterlogged then infiltration is reduced and surface runoff increases
Rock type
- Impermeable rocks don’t store water or let it flow through them, reducing infiltration and increases surface runoff, reducing lag time
Soil type
- Sandy soils allow lots of infiltration but clay soils have very low infiltration rates
Precipitation
- Amount of precipitation – more will cause a greater peak discharge
- Type of precipitation – snow can melt and run into the river in spring giving a very long lag time
Temperature
- Hot, dry conditions and cold conditions result in hard round, this reduces infiltration and increases surface runoff – reducing lag time and increasing peak discharge
- High temperatures can increase evapotranspiration so less water will reach the channel

Question 8

What are the human factors affecting river discharge and the storm hydrographs? (5)

Answer 8

Building of dams and reservoirs
- Traps water. Reduces volume off water in the channel especially in dry seasons
Deforestation
- Removal of vegetation decreases interception and vegetation storage, increasing surface run off, shorter lag time and higher peak discharge
Urbanisation
- New buildings increase the amount of interception which will decrease surface run off
- Tarmac and concrete stop infiltration into the bellow soils which increases surface run off
Climate change
- Humans are affecting global temperatures and more extreme weather
Agricultural
- Irrigation for plants removes water from the drainage system
- Use of machinery compacts the soil making it less able to infiltrate the water thus increasing surface run off

Question 9

Explain the storm hydrograph

Answer 9

A graph showing:
Peak discharge - greatest recorded discharge
Lag time - delay between peak rainfall and discharge, the time that it takes for the water to flow into the river
Rising limb - the increase in discharge as rainwater flows into the river
Falling limb - decreasing discharge as less water is flowing into the river

Question 10

What are the 3 types of erosion? What stages of a river do they occur in?

Answer 10

Headward erosion - makes the river longer by eroding back upstream, happens near the source as through flow and surface run-off cause erosion
Vertical erosion - makes the river channel deeper, happens in the upper stage of a river
Lateral erosion - makes the river wider, happens in the middle and lower stages of the river

Question 11

What are the five main ways that erosion happens?

Answer 11

Hydraulic action – the pressure of the water breaks rock particles away from the bed and banks, strongest in rapids and waterfalls and during flooding
Abrasion – eroded pieces of rock in the water scrape and rub against the bed and banks, removing material
Attrition – eroded rocks smash into each other and break into smaller fragments, the edges get rounded off as they rub together
Cavitation – air bubbled in turbulent stretches of water implode causing shockwaves that break pieces of rock off the bank and beds
Corrosion – dissolving of rock by chemical processes, carbon dioxide dissolves in water to form a weak acid which reacts with rocks like limestone and chalk to break them down

Question 12

What are the four main ways that eroded material can be carried by the river?

Answer 12

Solution – substances that can dissolve are carried along in the water, for example limestone is dissolved into river water that is slightly acidic
Suspension – very fine material, silt and clay, is whipped up by turbulence and carried along by the water, this is the way most eroded material is transported
Saltation – larger particles, pebbles or gravel, are too heavy to be carried by suspension, instead the force of the water causes them to bounce along the river bed
Traction – very large particles, boulders, are pushed along the river bed by the force of water
*Material transported by saltation or traction is called bedload

Question 13

Why does deposition in a river occur?

Answer 13

Deposition occurs when the river loses energy, it slows down and drops some of its load. The speed and energy can be reduced in many ways:
• Reduced rainfall causes lower discharge, reduces velocity of the river
• Increased evaporation or abstraction causes lower discharge
• Friction reduces the speed of a river
• The see absorbs the rivers energy when they meet

Question 14

What is the capacity of a river?

Answer 14

The total load that a river can transport at a given point, load can be divided into different categories according to particle size which can range from fine silt and clay to big boulders. The competence is the maximum particle size that a river can transport at a given point.

Question 15

Explain the Hjulstrom curve

Answer 15

A graph showing the link between river velocity and competence
The critical erosion velocity curve shows the minimum velocity needed for the river to pick up and transport particles of different sizes.
The mean settling velocity curve show the velocities at which particles of different sizes are deposited.

Question 16

How does the process of erosion change from the source to the mouth?

Answer 16

Upper stage
- Mainly vertical and by abrasion
- Erosion occurs where there are high-energy conditions.
- The rough channel causes turbulence and the large angular bedload is dragged along the river bed, causing intense vertical erosion
Middle stage
- Mainly lateral and by abrasion
- Attrition of larger particles in this stage ,means that sediment size decreases from source to mouth
Lower stage
- Less erosion because turbulence is lower and sediment particle size has been reduced
- Some lateral erosion occurs during the formation of meanders

Question 17

How does the process of transportation change from source to mouth?

Answer 17

Upper stage
- Mainly large particles such as boulders carried by traction or saltation during high-energy condition
Middle stage
- More material carried in suspension as particle size decreases
- Larger particles moved by saltation
Lower stage
- Mainly smaller particles such as silt and clay are carried by suspension or in solution

Question 18

How does the process of deposition change from source to mouth?

Answer 18

Upper stage
- Mainly largest particles deposited in the river bed as energy levels drop
Middle stage
- Sand and gravel are deposited across the flood plain as the river floods and friction reduces the river energy
Lower stage
- Smaller particles such as sand and silt are deposited on the flood plain where the river floods and in the river mouth as the sea absorbs the rivers energy

Question 19

What is the long profile? How does it change downstream?

Answer 19

A long profile shows how the gradient of a river changes from the source to its mouth by showing the height of the river bed above the base level for the length of the river. The base level is the lowest part that a river can erode to, usually sea level.
The upper stages have a steep gradient and the river is high above sea level so has lots of potential energy.
As the gradient decreases towards the middle of the river the energy is converted to kinetic energy giving the river more velocity.
In the lower stages the river has lots of kinetic energy so it flows faster.

Question 20

What is a graded profile?

Answer 20

In a long profile he total amount of erosion and deposition is balance but the rates change along the river causing landforms such as waterfalls. Over time the long profile will change to a smooth curve called a graded profile.

Question 21

What is the cross profile? How does the cross profile change downstream?

Answer 21

The cross profile shows what a cross section of the river channel or valley looks like, it has different shapes during different stages of a rivers long profile.
The upper valley is a steep v shape, vertical erosion creates narrow valley floors and steeply sloped sides.
In the middle stage the valley are wider due to lateral erosion, deposition at this stage creates a flood plain on the valley floor.
In the lower stages of the river the valley is wide with a much wider flood plain caused by further deposition.

Question 22

How and why does velocity and discharge change downstream?

Answer 22

Velocity and discharge increase downstream from source to mouth. Discharge increases as tributaries and more surface runoff join the channel, as there is more water in the channel the water flows faster and a smaller proportion of the water is in contact with the sides and beds there is less friction so the velocity is increased.

Question 23

What is hydraulic radius and how does it change downstream?

Answer 23

The hydraulic radius is a measure of a rivers efficiency. It is calculated by dividing the cross sectional area by the wetted perimeter. The higher the hydraulic radius the less water is in contact with the wetted perimeter, less friction, which reduces energy loss increasing efficiency, velocity and discharge. The wetted perimeter is increased by a rough channel, protruding banks and boulders, this decreases the hydraulic radius.

Question 24

How does channel roughness change downstream?

Answer 24

Channel roughness causes turbulence which is most effective at picking up particles from the river bed so causes greater erosion. The channel is roughest in the upper stages so the river loses a lot of energy to friction which causes discharge and velocity to be lowest here.

Question 25

Erosional landform

What is a potholes and how is it formed?

Answer 25

Small circular hollows in a river bed
Formed by abrasion as turbulence swirls a rivers bedload round in a circular motion causing it to rub and scrape out holes.

Question 26

Erosional landform

What are rapids and how are they formed?

Answer 26

Relatively steep sections of river with turbulent flow where there are several sections of hard rock.
Formed like waterfalls but produced by more gently inclined resistant rock that steepen

Question 27

Erosional landform

How is a waterfall formed?

Answer 27

Form when a band of hard rock meets softer rock which is eroded more creating a step in the river bed. The water flowing over the step speeds up as there is less friction giving the water greater erosive power. This causes further erosion of the soft rock and undercutting of the harder rock. As hard rock is undercut it can collapse and created a deep plunge pool through abrasion from the cut rock in turbulence.

Question 28

Erosional landform

How is a gorge formed?

Answer 28

Over time more undercutting of a waterfall causes more collapse and the water fall will retreat leaving a steep sided gorge.

Question 29

Erosional and deposition

What is a Meander and how is it formed?

Answer 29

Meanders are large sweeping curves found in the middle and lower stages of a river formed by erosion and deposition.
Form where there are alternating pool, deep water, and riffles, shallow water, develop at equally spaced intervals along a stretch of river. The distance between the pools is 5-6 times the width of the river bed.
The river is more efficient in the deeper pools so has greater energy and more erosive power whereas in the riffles energy is lost due to friction. The spacing between riffles and pools causes the rivers flow to become uneven and maximum flow to be concentrated on one side of the river.
Turbulence increases around the pools as water speeds us causing the water to twist and coil. Corkscrew like currents called helicoidal flow spiral from bank to bank between the pools causing more erosion and deepening of the pools and eroded material to be deposited on the inside of the next bend.
The combination of erosion and deposition exaggerates the bends until large meanders are formed and the distinctive asymmetric cross-section is created.
Oxbow lakes are formed when the neck and loop of a meander is broken through often during flooding, deposition dams off the loop leaving an oxbow lake.

Question 30

Fluvial deposition

What is braiding and how is it formed?

Answer 30

Little streams in a river caused by sediment deposition
Occurs when a river is carting a large amount of eroded sediment. If the velocity drops or the loads become too much for the river sediment is deposited in the channel.
This causes the river to divide into small channels which eventually re-join to form a single channel.

Question 31

Fluvial deposition

What are levees and how are they formed?

Answer 31

Natural raised embankments formed as a river overflows its banks. During a flood material is deposited across the flood plain as the river loses velocity and energy due to increased friction. The heaviest material is dropped first closest to the river channel, over time this builds up on the river bank to create a levee.

Question 32

Fluvial deposition

What is a floodplain and how is it formed?

Answer 32

Flat land either side of the river which is flooded when the river overflows.
When the river overflows there is an increase in wetted perimeter and reduction and hydraulic radius. Friction is increased reducing velocity of the river and causing fine silt and sand to be deposited across the flood plain.

Question 33

Fluvial deposition

What is a delta and how is it formed?

Answer 33

Braiding cause by deposition of deposits where a river reaches a lake of the sea.
The energy of the river is absorbed by the slower moving water of the sea or lake. This causes the river to deposit its load which builds up on the sea bed until the alluvium, the deposits, rise above sea level partially blocking the mouth of the river. The river has to braid in order to reach the sea causing a delta.

Question 34

What is rejuvenation?

Answer 34

Rejuvenation is the process where the base level of a river is lowered, caused either by the ground level rising, e.g. tectonic uplift, or by a drop in the sea level, e.g. due to climate change. The river now has greater potential energy which increases the vertical erosion potential. The long profile of the river is extended and a Knick point will form and mark the junction between the original long profile and the new one.

Question 35

What is a knick point?

Answer 35

A sharp change in gradient in a rivers long profile which is often a waterfall

Question 36

What is a river terrace?

Answer 36

former flood plains which are left above the present day level of flooding after increased rapid vertical erosion - rejuvenation

Question 37

What are incised meanders?

Answer 37

Formed when a river keeps its meandering course as vertical erosion increases, resulting in a deep, winding valley with steep side. There are two types;
• Intrenched which occur where down cutting is rapid and there is little erosion and weathering of valley slopes
• Ingrown which develop where there is a slower rate of down cutting and where valley slope decline is more significant.

Question 38

What is the magnitude-frequency analysis of flood risk?

Answer 38

Magnitude is the size of a flood, frequency is how often floods occur. Floods of very high magnitudes don’t occur that often whereas smaller floods do. Larger floods usually are caused by insula amounts of heavy of prolonged rainfall. The Flood return interval can predict how often a flood of a certain magnitude may occur by keeping records over many years.

Question 39

What are the physical causes of flooding? (8)

Answer 39

• Prolonged rainfall, after a long period of rain the ground becomes saturated and any further rainfall cant infiltrate leading to an increase in surface runoff which increases discharge
• Heavy rainfall, leads to rapid surface runoff if the rainfall is too intense for infiltration to occur
• Melting snow and ice
• Sparse vegetation or deciduous trees, sparse vegetation means little interception so more rain reaches the ground increasing the volume of water reaching the river, deciduous trees have no leaves in winter so there is little interception
• Impermeable ground, rocks or baked ground, don’t allow infiltration of surface water which increases surface runoff
• Circular drainage basin, all the water draining into the channel will arrive at the same time because all points are equal distances away
• High drainage density (lots of streams), drain quickly so have short lag times, lots of water flows from streams into the main river in a short space of time, increasing discharge
• Steep slopes, water will reach the channel faster

Question 40

What are the human causes of flooding? (5)

Answer 40

• Urbanisation, impermeable surfaces so surface runoff is very rapid, gutters and drains take runoff into rivers , both reduce lag time and so increase discharge
• Deforestation, reduces interception and evapotranspiration, increases the volume of water that reaches the channel , the soil becomes lose and is eroded and carried to the river reducing channel capacity
• Flood management strategies, e.g. if dams fail they release a huge volume of water all at once giving a huge increase in discharge
• Agriculture, overgrazing leave areas with less vegetation so less interception and more soil erosion, use of machinery compacts soils so it can infiltrate
• Climate change, can cause an increase in rainfall and more storms which can increase flooding

Question 41

What are the social impacts of flooding?

Answer 41

• People and animals are killed
• Lack of clean drinking water as it becomes contaminated with sewage
• Diseases from the contaminated water
• Possessions can be damaged or washed away
• People can be made homeless

Question 42

What are the economic impacts of flooding?

Answer 42

• Businesses often have to shut
• Rescue work and repairs are usually costly, insurance goes up
• Unemployment levels often rise as businesses shut down
• Public transport, roads and bridges can be destroyed
• Crops may be destroyed which can lead to rise in food prices

Question 43

What are the environmental impacts of flooding?

Answer 43

• Floodwater contaminated with sewage and rubbish can pollute rivers
• River banks are eroded
• Sediment is deposited on the flood plain making land more fertile
• Wetlands can be created, e.g. marshes and ponds which are habitats for species

Question 44

Case study - storm Desmond, Keswick/Cumbria December 2015

Causes

Answer 44

Physicals causes
• Little vegetation
• Steep slopes – quick flow
• Impermeable rock / slate – cant percolate
• Lots of tributaries into the river Greta
• Thin soils – little infiltration
• Antecedent conditions – saturated ground – 341mm of rain in 24 hours
Human causes
• Urbanisation – close to river
• Deforestation for sheep grazing
• Flood defences – more flooding downstream

Question 45

Case study - Bangladesh, South Asia 2007

Causes

Answer 45

Physicals causes
• Early, sudden monsoon – 80% of rain in 4 months
• Heavy rainfall, long durations – saturated soil
• Lots of tributaries, peak discharge of the River Ganges and Brahmaputra coincided
• Low land, 90% of land is less than 10m above sea level
• Melting snow off mountains
Human causes
• Deforestation in Nepal and Himalayas
• Growth of urban areas due to migration
• Collapse of old earth dams in Madhya India

Question 46

What is hard engineering in terms of flood management?

Answer 46

Hard engineering defences are man-made structures that reduce flooding. They are usually expensive to build and maintain, disrupt natural processes, can make floods more hazardous and are often considered to be ugly.

Question 47

What is soft engineering in terms of flood management?

Answer 47

Soft engineering uses knowledge of the whole river basin to try and work with nature. The methods are cheaper than hard engineering, improve opportunities for recreation and make flooding more predictable reducing the risk of an unexpected disaster. Soft engineering is more sustainable as it integrates with the natural environment, it has a low economic cost and environmental impact

Question 48

How does a dam work? What are the advantages and disadvantages?

Answer 48

Huge walls are built across rivers forming a reservoir behind the dam. Flood water is caught by the dam preventing flooding downstream, the water is released steadily through the year.
Advantages
- Turbines can be built to generate electricity.
- Steady release of water allows irrigation of land bellow.
- The reservoir can be used for recreation.
Disadvantages
- Very expensive
- Land if flooded when created often destroying farmland
- Affect wildlife
- Trap sediment which can cause the dam to fail and more erosion downstream as there is less protective sediment

Question 49

How does channel straightening work? What are the advantages and disadvantages?

Answer 49

Meanders are removed by building artificial cut through to make water flow faster reducing flooding because water drains downstream more quickly.
Advantages
- Takes less time to navigate the river because it is shorter.
Disadvantages
- Flooding may happen downstream instead
- More erosion because the river flows faster
- Disturbs wildlife habitats

Question 50

How do levees work? What are the advantages and disadvantages?

Answer 50

Embankments built along rivers to enable the river to be able to hold more water
Advantages
- Allow building on the flood plain
Disadvantages
- Quite expensive
- Risk of severe flooding if levees are breached

Question 51

How does a diversion spillway work? What are the advantages and disadvantages?

Answer 51

Channels that take the water elsewhere if the water level is too high, the water is normally diverted around an important area or to another river. They often have gates so the release of water can be controlled.
Disadvantages
- Increase in discharge when the diverted water joins another river
- If spillways are overwhelmed the water could flood areas not used to flooding

Question 52

How does land management work? What are the advantages and disadvantages?

Answer 52

Planning restrictions prevent buildings or roads being constructed in the flood plains, more water can infiltrate so there’s less surface runoff which reduces discharge and flooding
Advantages
- No new buildings or roads are at risk from flooding
- Recreational opportunities in the form of playing fields
Disadvantages
- Restricts development
- Can’t be used in an area that is already developed

Question 53

How does wetland and river bank conservation work? What are the advantages and disadvantages?

Answer 53

Wetlands store water and slow it down, conservation gives natural protection. Planting trees and shrubs along the river bank increases interception and lag time reducing discharge and decreasing flooding
Advantages
- Vegetation protects from soil erosion and provides habitats
Disadvantages
- Less farm land available

Question 54

How does river restoration work? What are the advantages and disadvantages?

Answer 54

Involves making the river more natural and allowing the flood plain to flood naturally. The river discharge is reduced which reduces flooding downstream
Advantages
- Little maintenance is needed
- Provides a better habitat for wildlife
Disadvantages
- Local flood risk can increase

Question 55

How do alternations to urban surfaces work? What are the advantages and disadvantages?

Answer 55

Building porous pavements or soakaways increase infiltration which reduces rapid surface runoff to the river channel.
Advantages
- Pollutants in the water are filtered out by the soil before the water reaches the channel
Disadvantages
- Expensive

Question 56

How does weather forecasts and flood warning work? What are the advantages and disadvantages?

Answer 56

The environment agency monitors weather forecasts, rainfall and river discharge, they warm people through TV, radio, newspapers and the internet enabling people to evacuate before
Disadvantages
- Some people may not have access to communications
- Flash floods may happen too fast for warnings
- People may ignore warnings if they were wrong in the past.

Question 57

Case study - River Yangtze, China

information and defences

Answer 57

The Yangtze River flows is the world third longest river at 6380 km long. Seasonal flooding is common causing huge problems as there is lots of farmland and loads of major cities next to the river. There has been five major floods over the last century in 1931, 193, 1949, 1954 and 1998. In 1999 3000 people were killed and 14 million were made homeless.
Defences
There are many dams on the river that reduce flooding, 46 are planned or under construction. The biggest is the Three Gorges Dam which began construction in 1994. A reservoir is building up behind the dam which can store around 22 km2 of flood water. It is also the largest hydroelectric station in the world with the power to turn 26 turbines. There are also artificial levees along the river which extend for 3600 km in the middle and lower parts of the river.

Question 58

Case study - Abington

Information and defences

Answer 58

Abingdon is a town in south-east England that was built on the flood plains of the River Thames and the River Ock. 1500 properties have a 1% chance of flooding in a given year and Abingdon has regular floods. Hard engineering defences have been considered but have been rejected for various reasons.
Defences
- Gravel soakaways have been built along the A34 road
- Low-value land is allowed to flood
- Planning restrictions on new housing developments on the Ock flood plain must have improved drainage systems
- Improvements have been made to riparian buffers along smaller rivers
- Restrictions on land use
- The environmental agency’s local flood warning plan warns specific areas at risk
- Local voluntary flood wardens communicate advice and warnings

Question 59

Case study - storm Desmond, Keswick/Cumbria December 2015

Management

Answer 59

• Pedestrian bridge widened and made single span to stop debris getting caught
• Within houses – tiled floors, mainly living upstairs, flood doors
• Playing field lowered so river floods that way instead of into town, drainage pipes
• Broken down weir to slow water
Embankment to protect the hospital – enlarged after the 2009 floods
• Wall to protect lower town, now been made higher with glass wall but didn’t stand the amount of water during storm Desmond
• Rounded supports on bridges

Question 60

Flooding case studies conclusion

Answer 60

Flooding in Bangladesh has such a large impact because the country is less economically developed. Therefore they lack technology for prediction, evacuation and equipment for rebuilding their lives. They are also very reliant on the primary sector which is easily destroyed by the floods. However with help from international countries Bangladesh are able to use soft engineering to manage frequent flooding. In Cumbria, as a high economically developed area the flooding cause widespread disruption to daily lives in the form of transport and businesses. However the government are able to invest in new schemes of management on large scale and small scale, within houses. Therefore although the impact is large due to stability of the economy it has a less drastic impacts than flooding in Bangladesh.

Question 61

Case study - River Yangtze China

Effects

Answer 61

Positives
- Thought to have reduced major flooding from once every 10 years to once every 100 years
- Turbines in the dam produce a lot of electricity, enough to supply 3% of Chinas demand
- Reduction in flooding has made if safe to navigate up the river, river shipping has increased
Negatives
- Between 1.3 and 2 million people in total will gave to relocate by the time the reservoir is full, 13 cities and 1352 villages will have been submerged
- The reservoir will flood farmland, 657 factories and 1300 sites of cultural and historic interest, the Temple of Zhang Fei will be submerged
- The dam could destroy habitats and endangered species e.g. there is less than 100 baji dolphins left in the Yangtze
- The three gorges dam doesn’t protect everyone as water levels will rise along the tributaries

Question 62

Case study - Abingdon

Effects

Answer 62

Soft engineering reduces damage but flood still happen. The 2008 flood did less damage than in previous years with minimal cost, little disruption to the community, no lives lost and only a few injured. However flooding does still occur in Abingdon.

Question 63

Case study - storm Desmond, Keswick/Cumbria December 2015

Impacts

Answer 63

Social
• 1 death
• 1000’s evacuated, many temporarily homeless
• Travel disrupted – trains, buses – and a major road within the lake district destroyed and closed for months
• 4 schools severely flooded
• Increase in stress-related illness
Economic
• Cost about £100 million, estimated year to fix damage
• 100’s off business had to shut as no electricity – united biscuit 33 people lost jobs after £5 million of damage
• 60,000 houses without power
Environmental
• River bank erosion increased
• Rivers polluted with rubbish and sewage

Question 64

Case study - Bangladesh

Impacts

Answer 64

Social
• Over 2000 deaths as reluctant to evacuate and leave livestock, evacuation was slow due to transport and many drowned as they could not swim
• Over 100,000 caught water borne diseases as water became polluted
• 25 million became homeless
• 112,000 houses destroyed as made from mud bricks
• 4,000 schools affected and 44 completely destroyed
Economic
• Cost estimated at 1 billion for damage on crops and property
• Factories closed, unemployment
• Loss of livestock
• 550,000 hectares of land couldn’t be planted – world basmati rice price rose by 10%
• 100,00km of road destroyed
• Individual and national debt increased
Environmental
• Fertile silt on the flood plains
• Rivers polluted with sewage

Question 65

Case study - Bangladesh

Management

Answer 65

• Waterlog fields converted into ponds for crabs and shrimps
• Solar powered school boat offers education all year round even in flooded areas
• Floating gardens
• Cyclone shelters/ community buildings with stilts to shelter when flood comes
• Artificial levees to reduce the flood water
• Houses on stilts
• Planting trees in the mountains for interception
• Support from more economically developed countries – education, risk mapping and equipment
• BRAC – health workers