CASE STUDIES Flashcards

Question

CASE STUDY: The Millennium Drought - Why?

Answer 1

A result of physical and human causes. El Niño prevailing conditions explained about two-thirds of the rainfall deficit in eastern Australia. Strengthening of high-pressure belt, the subtropical ridge (STR) blocked storm tracks (depressions), forcing them towards higher latitudes and thereby reducing frontal rainfall. Changes to the Hadley Cell and the STR associated with anthropogenic global warming; in particular, the STR appears to have intensified as global surface temperatures increased, blocking storm tracks.

Answer 2

It is thought that anthropogenic warming is reducing the temperature gradient between the Equator and the Pole, which would reduce the energy available for mid-latitude storm systems and the polar front jet stream. So less rainfall. However this is an ongoing investigation, and sufficient evidence is yet to be collected to prove this relationship.

Answer 3

Reduced rainfall - reduced crop yield, increase of wildfires.

Answer 4

Uzbekistan and Kazakhstan

Answer 5

The water supply from two rivers, the Amu Darya and Syr Darya, which carry snow melt from mountainous areas, was diverted by the Soviet Union for irrigation to produce cotton. This eliminated any river inflow to the Aral Sea causing it to disappear.

Answer 6

Shrank 10% of its original size

Answer 7

2060km³. By 1980s it received no freshwater.

Answer 8

24 fish species extinct (could not adapt to more saline waters) Wetlands of the two river deltas have disappeared Regional climate is drier and has greater temperature extremes due to the absence of moisture and moderating influence from the lake Southern part of the Aral Sea has seen no relief and remains nearly completely dry

Answer 9

Once thriving fishing industry removed Current shoreline is tens of kilometres from former fishing towns and commercial ports Rive diversion project meant that many of the irrigation canals were poorly built, allowing abundant water to leak or evaporate Increasing number of dust storms, blowing salt, pesticides, and herbicides into nearby towns causing respiratory illnesses including tuberculosis

Answer 10

Lake Chad in Africa

Answer 11

Large lakes destroyed by unsustainable diversions of river water.

Answer 12

Dead Sea - Middle East Lake Manchar - Pakinstan Owens Lake - California Mono Lake - California

Answer 13

High pressure blocks the arrival of the wet season.

Answer 14

Africa, at the southern edge of the Sahara desert. Covers parts of 11 countries.

Answer 15

Possible reasons: Air pollution generated in Europe and North America. These pollutants are thought to have caused atmospheric cooling, so that tropical rains associated with the ITCZ did not arrive, causing drought. As a results of higher sea-surface temperatures caused by atmospheric climate warming. Rain-bearing winds that move over the Sahel appear to fail when the sea-surface temperatures in the tropical Atlantic Ocean are warmer than average. El Niño would increase water stress. Cooler waters in the North Atlantic added to the drying conditions with reduced evaporation.

Answer 16

Strong south-westerly rain-bearing winds.

Answer 17

The ITCZ doesn't move as far north as it should, due to high pressure in the north preventing the south-westerly winds bringing the usual rain. Anticylone - blocks out potential of ITCZ migrating further north.

Answer 18

Demand for food and fuel wood is accelerating. Natural dryland ecosystems are progressively being converted into farmland which is being overcultivated and overgrazed. Causes desertification.

Answer 19

Reduced vegetation cover and soil moisture, could create self-perpetuating droughts.

Answer 20

Desertification increases human vulnerability to the drought hazard.

Answer 21

December 2015 - storm that brought severe gales and heavy rains to the UK, Cumbria was the worst hit county - a months worth of rain fell in one day (350mm in some places).

Answer 22

Localised flooding in north-west England, southern Scotland, north Wales, and parts of Northern Ireland.

Answer 23

Very low air pressure and its fronts brought exceptionally prolonged and heavy rainfall as the air was forced to rise across the high ground of the Lake District. Convectional and orographic precipitation was combined and, together with already saturated ground, created conditions for extreme flooding. Existing flood defences unable to deal with water levels.

Answer 24

Red River in North Dakota, USA Norfolk 2013

Answer 25

The Cumbrian fells created orographic rainfall (occurs in areas where land increases height). The moist air mass stayed over Cumbria for up to 48hrs - delivering record amounts of rain.

Answer 26

June and July 2007

Answer 27

High-altitude westerly jet stream stayed south of Britain instead of making its seasonal shift northwards. Heavy rain followed. Also due to a low pressure system located over Calais in the morning which slowly moved northwest bringing warm, continental air. This, when meeting the cooler air to the North, created an area of instability ideal for storm generation. Soils were already saturated due to the heavy rainfall occurring in the months leading up to the flooding. This meant water could not infiltrate into the ground, causing overland flow and intensifying the floods.

Answer 28

South-west England and South Wales

Answer 29

- lakes were contaminated with drain refuse and sewage - runoff from torrential rain meant that the Ea Beck burst its banks, sending torrents of water and debris into Toll Bar and Bentley - green spaces flooded and ground saturated

Answer 30

- national death toll reached 7 - 27,000 homes were damaged - 5,000 businesses had to be evacuated - in Hull 30,000 people had to leave their homes at the height of the crisis - major roads were closed like the M1 - residents in 120 flats in Lincoln were evacuated

Answer 31

- total bill to insurers is put at around $3.3 billion - overall government support for the flood hit regions is $46 million - rising interest rates - the Environment Minister pledged to boost spending on flood defences by £200 million a year by 2011

Answer 32

Between 2000 and 2003

Answer 33

South-west USA, New Mexico

Answer 34

Hot dry conditions made the Piñons more susceptible to pine bark beetle attacks.

Answer 35

In the Pacific Islands, small and low-lying.

Answer 36

Small aquifers for their freshwater supply.

Answer 37

Saltwater intrusion, as a result of over-abstraction, climate variability and sea-level rise. Population growth has increased water demand, resulting in an increase in groundwater pumping and a consequent lowering of the water table.

Answer 38

Crop production depends on freshwater irrigation, making saltwater intrusion a serious threat to health, food security and livelihoods.

Answer 39

Southern Pakistan

Answer 40

90% of Karachi do not have access to legal piped water Global cost of water Water theft, illegal water hydrants, corrupt water board Climate change means there's less rain Agriculture suffering Piped water can be dirty/sewage However some areas, e.g "The Fence", are rich. Some pat 4,000 rupees for a tank of water every 3 days Link to urbanisation - cities cannot meed the population's demand for water.

Answer 41

In several of the world's intensive farming areas such as the 𝗡𝗼𝗿𝘁𝗵 𝗖𝗵𝗶𝗻𝗮 𝗣𝗹𝗮𝗶𝗻, and around numerous megacities such as 𝗕𝗲𝗶𝗷𝗶𝗻𝗴.

Answer 42

1.35 million m³ of contaminated water.

Answer 43

Mining operations and contained arsenic at 300 times normal levels, and lead at 3,500 times normal levels.

Answer 44

People and livestock downstream were at risk and access to the river was closed; people with wells were told not to use the water without testing.

Answer 45

A local state of emergency was declared by the Navajo Nation Commission on Emergency Management.

Answer 46

Faced widespread criticism. * Suspended other clean up operations to allow the EPA time to develop emergency plans in case similar accidental pollution occurred. * EPA opened a temporary water treatment plant at the Animas River mine, a cost of US$1.8 million, to treat the polluted water.

Answer 47

The government in Denmark decided to raise water prices.

Answer 48

More than 20 years ago, regulation requiring certified metering of all water consumption was set up in Denmark, introducing tax on both water consumed and water supplied, as well as on Non-Revenue Water.

Answer 49

High price deters unnecessary consumption.

Answer 50

From 1989 to 2012, the price of water for customers in Denmark has risen from around €2 to €7 euros per cubic metre.

Answer 51

The increased price is aimed at covering the supply of water (22%), sewage and wastewater treatment (47%), and taxes (31%).

Answer 52

Increased public awareness about saving money. There has thus been a significant drop in water consumption in Denmark from a per capita average of 170 litres per day in 1989 to 114 litres per day in 2012.

Answer 53

1989: per capita consumption was 170 litres per day 2012: per capita consumption was 114 litres per day

Answer 54

The Water Framework Directive, which set out requirements for national water pricing policies. It's goal was to provide adequate incentives for efficient water usage as well as to incorporate a user contribution to the cost of providing appropriate water services.

Answer 55

An incentive to reduce water losses because the amount of water supplied was taxed.

Answer 56

Almost one euro per cubic metre.

Answer 57

* Impose additional penalties on water utilities that to not reduced Non-Revenue Water to less than 10%. * Created a strong incentive for water utilities to reduce urban water loss and to plan, manage and operate the utilities efficiently to the benefit of both the consumers and the environment.

Answer 58

The Salton Sea in the dry south-eastern part of California.

Answer 59

A productive ecosystem, with fish in its waters and invertebrates in its muds, providing a food source for over 400 species of birds, including pelicans and egrets. Millions of birds use the Sea as a stopping point when migrating along the Pacific Flyway.

Answer 60

Water levels have been falling as evaporation from its shallow waters (15 metres deep) exceeds inflow, causing salinity levels to increase (over 50 g/l).

Answer 61

* Water is in great demand in southern and central California, so water that should reach the Salton Sea is diverted to agriculture, and some inflow consists of contaminated runoff from the fields. * The Salton Sea is also affected by regional water agreements, and from 2017 to 2018, there could be an 18% decline of inflow, as water will no longer be diverted to it from the Imperial Irrigation District, causing the Sea to shrink by up to 260km².

Answer 62

* Water levels have been falling as evaporation from its shallow waters exceeds inflow, which increases salinity levels. * Water that has been diverted to agriculture has resulted in contaminated inflow to the Salton Sea. * Regional water agreements have resulted in diversions, causing the Sea to shrink by up to 260km².

Answer 63

Sahara Desert - an arid region in which fossil water in aquifers may be extracted for human purposes (agriculture, industry and consumption), but there is little to no significant recharge, effectively making this type of groundwater a non-renewable resource.

Answer 64

Mawsynram in India, with 11,873mm of rain per year, mostly during the monsoon season between June and September. High precipitation input into drainage basins.

Answer 65

In stable areas of high atmospheric pressure, such as Quillagua in the Atacama Desert, Chile which is the driest place on Earth, receiving less than 0.2mm of rain per year.

Answer 66

Average 11,000mm of rain per year.

Answer 67

Less than 0.2mm - it is the driest place on Earth.

Answer 68

Gobi Desert in Asia and Alice Springs region in Australia are continental interiors, meaning they are far from the moisture of maritime air masses, so are examples of areas with very little rainfall.

Answer 69

The dense and multiple canopies of vegetation meant that rates of interception and evapotranspiration are high. This causes high humidity and heavy local convectional rainfall and is an example of a self-sustaining cycle as water is effectively recycled within the tropical forest system.

Answer 70

Because this is important to key agricultural regions of Brazil and other countries.

Answer 71

Deforestation may be significantly reducing evapotranspiration and precipitation, while also increasing runoff and river discharge. E.g the Tocantins River in Brazil showed a 25% increase in river discharge between 1960 and 1997, coincident with increased deforestation. Deforestation has also resulted in a lowering of humidities and more soil erosion and silt being fed into rivers.

Answer 72

The river showed a 25% increase in river discharge between 1960 and 1997, coincident with increased deforestation.

Answer 73

* China used cloud seeding in Beijing just before the 2008 Olympic Gamed to create rain to clear the air of pollution. * Used in the Alpine Meadows ski area in California to improve snow cover. * Used in Texas 2015 to reduce the impact of drought.

Answer 74

Winchester and Maidenhead (2014 floods) and Carlisle, York and Manchester (2015 floods). Urbanisation has therefore increased flood risk

Answer 75

Lake Nasser behind the Aswan Dam in Egypt is estimated to have evaporation losses of 10-16 billion cubic metres every year. This represents a loss of 20-30% of the Egyptian water volume from the River Nile.

Answer 76

China - groundwater extraction is increasing by about 2.5 billion cubic metres per year, and consequently groundwater levels in the arid North China Plain dropped by as much as a metre a year between 1974 and 2000. Groundwater is used to irrigate more than 40% of China's farmland and provides about 70% of the drinking water in the dry northern and north-western regions.

Answer 77

In some of the UK's major conurbations, including London, Birmingham, Nottingham and Liverpool, as a result of reduced abstraction for industry.

Answer 78

The Amazon - its peak discharge is in April - May and lowest discharge in September which is linked to wet and dry seasons.

Answer 79

The Yukon River - its peak discharge is in May-June with a dramatic increase due to melting snow and ice, it is low from December-May due to low precipitation and frozen conditions.

Answer 80

The River Nile - the flow below the dam was reduced by 65% and became regulated between seasons so that the flood peaks in September were reduced.

Answer 81

+ Akosombo is a rockfill dam. A rockfill dam is a structure built mainly of compacted rock and shaped like an embankment or hill. + The Akosombo Dam was politically important and it was seen as proof of Ghana’s ability to build major infrastructure projects. + Originally, the project supplied Ghana’s aluminium industry with the power it needed. Today the scheme provides 85% of the country’s electricity. - The Volta Lake is now a habitat for disease-carrying insects such as black flies and mosquitoes. - People from 700 different villages – many of whom were subsistence farmers - were moved into 52 resettlement villages as part of the scheme.

Answer 82

River Kent made up of impermeable igneous rock in the north and permeable limestone in the south. Mean discharge is 8.89 cumecs. River Lambourn made up of porous chalk. Mean discharge is 1.69 cumecs.

Answer 83

WEST because the western hills force moist air to rise as it approaches from the Atlantic - as it rises, it cools over high ground - producing heavy rain over western and northern parts of the UK. Specifically, the Scottish Highlands have highest rainfall because it has the highest relief, so more warm, moist air is forced to rise and condense.

Answer 84

An estimated 200 billion cubic metres of freshwater which is 70 years supply at Kenya's current rate of use, even without the natural replenishment it receives from mountain streams.

Answer 85

The arid Turkana region of northern Kenya.

Answer 86

* Brings hope to the drought-hit region * Another aquifer was found in Namibia-sub-saharan Africa and poor parts of Kenya but was hit by drought recently.

Answer 87

Positive water balance - more precipitation e.g more rainforests.

Answer 88

Negative water balance - deserts.

Answer 89

River Thames, Alpine Rhone, River Volta, Streams of Sicily, River Congo, River Yenisei

Answer 90

River Thames, Alpine Rhone, River Volta, Streams of Sicily, River Congo, River Yenisei

Answer 91

Caused Malham Cove (in the Pennines of North Yorkshire) to become a waterfall for the first time in centuries, because Malham Cove is a limestone area, and limestone is a permeable rock so water usually flows through. Storm Desmond in 2015 saturated the limestone.

Answer 92

Surface soils become saturated which reduces the ability of the landscape to absorb the excess water.

Answer 93

Cumbria - its annual rainfall is over 2000mm. Within that, places such as Borrowdale receive up to 3,300mm a year.

Answer 94

The ice in the Polar regions and in mountain glaciers is melting without being replenished.

Answer 95

Polar: - Winter snow insulates the ground and 85% of solar radiation is reflected - Permafrost creates impermeable surfaces - Limited vegetation cover reduces heat absorption - Annual precipitation is less than 200mm Tropical rainforest - Dense vegetation intercepts and consumes up to 75% of precipitation - 50-75% of precipitation then returns by evapotranspiration. - Evapotranspiration cools the air as energy is used during the process - Annual precipitation is over 2000mm

Answer 96

Dense forest produces high rates of evapotranspiration, with water returning to the surface as precipitation that feeds large rivers such as the Amazon.

Answer 97

Oceans and groundwater

Answer 98

Evaporation 400,000km³ per year Precipitation 370,000km³ per year Oceans therefore lose more water through evaporation than they gain through precipitation. The opposite is true for landmasses, who gain more through precipitation. This is because the cycle makes sure the oceans receive less water so the continents are not dry.

Answer 99

Beneath Greenland's ice sheet and under the Kenyan desert.

Answer 100

In the polar regions and beneath many deserts.

Answer 101

The Mississippi basin drains nearly 3.3 million km², much of it remote, while the Thames basin drains 16,000 km², and is very densely populated.

Answer 102

Western side of the UK

Answer 103

Saturated surfaces, high water tables and antecedent moisture - all of which make flooding more likely.

Answer 104

East Anglia

Answer 105

The Thames Basin - home to 13 million, and averages just 690mm of rainfall a year.

Answer 106

Over 40% of London's water comes from chalk aquifers. These are replenished by rain falling on the Marlborough Downs to the west of London, the Chilterns to the north, and the North Downs to the South. Abstracting too much water from groundwater reserves leads to rivers drying up in times of low rainfall.

Answer 107

Clearing of forests for new roads and palm oil plantations, and modern agribusinesses.

Answer 108

* In the Tropics, mats of floating plants on the reservoir's surface make evapotranspiration six times higher than in open water. * Salinity levels within the reservoir can also rise as its water evaporates. * Dams reduce the river flow below them, leading to the loss of vegetation e.g Kenya's Tana River floodplain forest is dying because dams built upstream have now eliminated floods there. * Reservoirs abstract water from the drainage basin.

Answer 109

Kenya's Tana River floodplain forest is dying because dams built upstream have now eliminated floods there.

Answer 110

From October. Storage areas are recharged by that point, and are usually full by January.

Answer 111

Effective rainfall is the amount of precipitation remaining after evaporation. Great Wakering in Essex and Coronado Memorial Park in Arizona, USA, receive similar annual rainfall, but the higher temperatures in Arizona means the rainfall effectiveness is lower and less rainfall remains. Rainfall in Essex is spread throughout the year, whereas Coronado in Arizona has short intensive bursts separated by periods of drought.

Answer 112

The Rhône at Gletsch Arve at Chamonix The rivers respond to localised factors within southern France and Switzerland.

Answer 113

- Mississippi River - Ganges - Amazon River - The Yukon River, Alaska - Murray-Darling, Australia - Indus River, Pakistan

Answer 114

Tundra, taiga and mountain climates. Higher summer temperatures, rainfall and snowmelt coincide. Some HEP for mining industries. High flow is in spring and summer, caused by melting snowmelt

Answer 115

Rainforest climate Seasonal precipitation - rainfall in every month Evapotranspiration levels very high Human influences are increasing; large dams used by Brazil's major cities for irrigation and HEP.

Answer 116

Seasonal sub-tropical climate - monsoon climate in northern tributaries of Queensland, which feeds the Darling; temperate climate in the south, which feeds the Murray. Most of the basin lies in a rain shadow and undergoes long periods of drought. Its waters are drawn by Australia's major cities and farms for irrigation.

Answer 117

Planners - within England, the National Planning Policy Framework (NPPF) sets out strict guidelines.

Answer 118

Sustainable Drainage Systems (SuDS)

Answer 119

* green roofs - vegetation cover planted over a waterproof membrane e.g on Adnam's Brewery distribution centre in Southwold, Suffolk * infiltration basins - shallow depressions dug out to delay runoff and increase infiltration * permeable pavements - to delay runoff by using gaps between pavement slabs * rainwater harvesting - collecting rainwater from roofs to be recycled e.g for irrigating gardens * soak-away - a channel dug out to disperse surface water into the ground. * filter drains - trenches filled with gravel to take runoff away * detention basins - to deal storm runoff for a few hours * wetlands - retention areas with marsh/wetland vegetation.

Answer 120

Singapore has invested in research and technology to create a diversified water supply, comprising local catchment water, imported water and desalinated water.

Answer 121

* Local catchment water involves collecting rainwater through a network of drains, canals, rivers, storm-water collections ponds and reservoirs before it is treated to supply drinking water. * Singapore has an agreement until 2061 to important water from Malaysia. * NEWater is high-grade recycled water produced from used water that is treated and further purified using advanced membrane technologies and ultraviolet disinfection, making it ultra-clean and safe to drink. Together, Singapore's four NEWater plants can meet up to 30% of the nation's current water needs.