Geography > Hydrological Cycle > Flashcards

Hydrological Cycle Flashcards

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1
Q

How does deforestation affect a drainage basin? Example?

A

Amazon

  • water cycling: 75% of intercepted water is returned to atmosphere by EVT, reduces to 25% when trees are reduced. Leads to more surface runoff as more water will saturate soil - potential flooding..?
  • deforestation happens due to cattle ranching, large scale agriculture for biofuels and soya beans, general development of towns and roads, and legal and illegal logging.
  • containing 60% of worlds rainforest, acts as green lungs by removing CO2 from atmosphere.
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2
Q

What is an example of over abstraction?

A

Aral Sea

  • shrunk dramatically, and is mostly gone due to Soviet Union diverting rivers to irrigate cotton fields - 1950s - 1960s.
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3
Q

What are the human impacts on drainage basins

A

Over-abstraction - eg Thames, Murray Darling, Mexico City

Deforestation - Amazon. ; removes vegetation which reduces interception and therefore increases infiltration and surface runoff.

Changing land use - urbanisation increases interception and stops infiltration which means more surface runoff.

Reservoirs - interrupt natural flow of water; estimated 7% more water is evaporated from reservoirs than used by people.

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4
Q

What are river regimes

A

The pattern of flow of a river throughout the year.

Complex = larger rivers that cross several relief and climate zones, therefore they experience the effects of different seasonal climatic events. - Amazon, Yukon

Simple = river experiences a period of seasonally high discharge, followed by low discharge; typical of rivers where inputs depend on glacial meltwater or seasonal storms.

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5
Q

What are the characteristics of the river Yukon

A
  • High flow in summer and spring due to snow melt
  • low flow in winter when water freezes
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6
Q

Characteristics of the Amazon river

A
  • high flow in wet season
  • low flow in dry season
  • seasonal variability = moderate; fed by Andean rivers outside rainforest region.
  • human influences = dams and deforestation
  • rainforest climate
  • evapotranspiration levels very high
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7
Q

Murray darling characteristics

A
  • High flow in wet season, low in dry season
  • high seasonal variability
  • human influences: its waters are drawn by Australia’s major cities and farms for irrigation = over abstraction

Influences:
- seasonal sub tropical climate; monsoon climate in northern tributaries of Queensland = increases discharge during rainy seasons

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8
Q

Why do storm hydrographs vary?

A

Reflects localised and contemporary characteristics of the drainage basin
- every change in land use and previous period of weather will determine timing and height of the peak

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9
Q

What are physical factors that affect hydrographs?

A
  • size of catchment
  • shape - some catch more water
  • drainage density - more tributaries = more efficient
  • rock permeability
  • soil characteristics
  • relief
  • veg type
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10
Q

What are human factors that affect hydrographs?

A
  • land use - deforestation reduces vegetation cover, ploughing furrows up/downslope increase surface runoff
  • urbanisation
  • water management
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11
Q

How do hydrographs in rural areas and urban areas vary?

A

Urban: high levels of impermeable surfaces = shorter lag time and higher peak flow - due to more runoff
• steel rising limb

Rural: more permeable surfaces = longer lag time as water takes longer to reach river.
• gradual rising limb

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12
Q

What is meteorological drought?

A

Due to a rainfall deficit which causes a loss of soil moisture and the supply of irrigation water declines.

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13
Q

What is hydrological drought?

A

Caused by a stream flow deficit and leads to reduced storage in lakes and reservoirs, less water for urban supply and power, and threats to wetlands and wildlife habitats.

  • this can lead to soil moisture deficits, creating an agricultural drought - crops damaged, livestock productivity declines, some gov aid may be required.
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14
Q

Describe a high and low pressure system

A

Warm air rises and condenses in the atmosphere to form clouds = rainfall - low pressure

Cold air sinks = no clouds = no rain
- high pressure.

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15
Q

What are the 3 cells called?

A

Hadley cell = 0 - 30 degrees

Ferrell cell = 30 - 60 degrees

Polar cell = 60 - 90 degrees

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16
Q

What are the features of the polar cell?

A

= cool air sinks at 90* due to low insolation. Coriolis effect causes cold air to move south along the surface - these are called the polar winds. These meet the warm westerlies and cause them to rise = low pressure at 60*

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17
Q

What are the features of the Ferrell cell?

A

At 30, the sinking air from the Hadley cell forms high pressure, the warm surface air moves from high to low pressure = westerlies. When these winds meet cold air from polar cell, it rises, cools and condenses into clouds at 60

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18
Q

What are the features of the Hadley cell?

A

High levels of solar insolation at the equator causes air to rise, forming a low pressure. = clouds and rain. Due to Coriolis, this air moves north.

It sinks at 30* as it is now cool, and causes high pressure.

Surface air moves from areas of high to low pressure - these are called trade winds in the Hadley cell.

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19
Q

Describe a normal year

A

Pacific winds circulate the walker cell. Winds travel west taking warm surface water with them. Warm moist air rises over Indonesia/Australia creating low pressure and heavy rain. The air then circulates east in the upper atmosphere, sinking into cooler high pressure over South America = dry conditions from the deserts.

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20
Q

Describe an El Niño year

A

Warmer waters in the eastern pacific cause low pressure = draws westerly winds from pacific. Warm, moist air rises creating heavy rainfall over South America. This then circulates west in the upper atmosphere and descends over Australia creating high pressure and leading to drought.

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21
Q

Describe a La Niña year

A

Low pressure over west pacific becomes lower and high pressure over the eastern pacific becomes higher. As a result, easterly trade winds become more intense and even more warm water is taken west. This causes flooding in Australia and Indonesia

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22
Q

What are the physical causes of drought in the Sahel?

A

•Almost all rainfall - 85% - occurs in summer
•unusually warm waters cause more upwelling = more rainfall over Atlantic rather than over land.
•Albedo effect = the reflectivity of the surface causes solar energy to reflect back into the atmosphere, increasing evaporation and reducing the potential for rainfall. - exacerbated by deforestation

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23
Q

What are the human causes of drought in the Sahel

A

•Overgrazing of nomadic tribes and deforestation cause land degradation and desertification.
•deforestation also worsens the Albedo effect - less trees = more reflective land exposed. Also leads to less moisture getting into atmosphere by transpiration.
•population growth = more demand
•unsustainable water extraction
•civil conflicts

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24
Q

When was storm Desmond?

A

December 2015

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25
Storm Desmond info
• caused by deep Atlantic low pressure system • 341.4mm rain in just 24 hours • 405mm rain fell at Thirlmere in 38 hours • 5200 homes flooded • 61000 homes lost power
26
How did human activities exacerbate the flood risk in Cumbria
Management was planned around floods happening every 100years - so walls only built 4.4m high - flood happened six days later = river rose to 5.9 meters and overtopped the defenses.
27
How is climate change affecting run off and stream flow?
Along with more climate extremes, there will also be an increase in hydrologic extremes, with more low flows (drought) and high flows (flooding). • an accelerated cycle with more intense rainfall will increase runoff rates and reduce infiltration.
28
How is climate change predicted to impact ENSO cycles?
La niña and el niño will increase in frequency due to warmer waters in the west = more flooding in Australia Intensity of rainfall for both La Niña and El Niño will increase - (Australia and South America respectively).
29
How many Californians facing problems due to variations in rainfall?
40 million
30
What is the increase in wildfires in Sierra Nevada?
3 times more than usual in 2014
31
What is physical water scarcity?
Insufficient water to meet the demand.
32
What is economic water scarcity?
When water is available, but not accessible due to a lack of infrastructure, technology, or investment. Usually occurs when there are not enough resources to provide clean water to everyone, despite the overall water supply being sufficient.
33
What is virtual water?
Water transferred by trading in crops and services that require large amounts of water for their production
34
What are some factors causing an increase in virtual water consumption?
• Rising standards of living - for example people adopting more meat based diet = requires more water for agricultural process. • economic growth = increases demand for water in all economic sectors. The mining of unconventional energy sources, for example fracking, puts a huge demand on water.
35
What percentage of fresh water usage does agriculture 占める？
70%
36
What percentage of fresh water usage in NEEs does industry 占める？
60% - particularly in metal, paper, and textiles.
37
How much has meat consumption increased by in China?
From 5 - 50kg annually.
38
Who controls water?
Control has started shifting to private sector due to IMF requirements (privatisation - restrictions put on Gov spending on services such as water) - has led to increased prices
39
What are the 4 factors affecting cost of water?
Cost of obtaining supply Demand of water Insufficient infrastructure Supplier
40
What happened in Cochabamba in 1999-2000?
A major uprising in Cochabamba, Bolivia, where citizens protested against the privatisation of the city’s water supply after prices rose sharply. The protests forced the government to cancel the privatisation contract.
41
Why did Bolivia’s gov privatise water?
Pressure from the World Bank, which made loan support conditional on water privatisation. Bolivia’s government wanted investment to expand and modernise water infrastructure.
42
What is the TNC in Bolivia that took control of the water services?
Aguas del Tunari owned by US company Bechtel
43
How much did water prices rise by in Cochabamba?
200% due to TNC wanting to recover costs of infrastructure
44
How many people rioted in Cochabamba?
80,000
45
How does the cost of obtaining supply affect water prices?
If water has to be transported a long way, this costs more money. Eg LA gets water piped from Colorado = expensive.
46
How does the demand for water affect prices?
If water is scarce, price increases in order to manage demand. - poor people often miss out
47
How does insufficient infrastructure affect water prices?
Areas without proper water services rely on unofficial water vendors - they charge high prices to make money. Eg in Manila costs are 4x higher
48
How does the water supplier affect prices?
Water prices are strongly affected by the type of water supplier and how water services are organised, particularly whether supply is public or private, the scale of the company, and the costs they face. In countries where water is supplied by private companies (such as England and Wales), prices are often higher because suppliers need to cover operating costs, infrastructure investment, and make a profit for shareholders. Private suppliers may invest heavily in reservoirs, pipes and treatment plants, and these costs are passed on to consumers through higher water bills. Prices can also vary between regions depending on how expensive it is to supply water locally. Where water is supplied by the state or local government, prices are often lower because the aim is to provide universal access rather than profit. Governments may subsidise water to keep it affordable, especially for low-income households. However, this can sometimes lead to underinvestment in infrastructure, resulting in leaks or unreliable supply. The size and location of the supplier also matter. Suppliers serving large urban areas can benefit from economies of scale, reducing the cost per household. In contrast, suppliers in rural or water-scarce regions face higher costs due to longer pipe networks, pumping, or desalination, which increases prices. Finally, regulation affects prices. In the UK, water companies are regulated by Ofwat, which sets price limits. Where regulation is weak or absent, suppliers may charge higher prices or provide unequal access.
49
How many did the fishing industry employ in Kazakstan?
60,000
50
How is local health impacted around the Aral Sea?
Salt and sand from seabed causes cancers - chemicals in the sand from weapons testing and fertiliser exacerbates the effect.
51
Who are the key players in the Aral Sea?
• former soviet gov - irrigation for fruit and cotton • fishing community - collapsed • local residents - health and economic impacts • Uzbekistan gov - irrigation schemes made Uz one of largest cotton exporters in the world • kazak farmers - irrigation has brought the water table to the surface = drinking water and food crops salty and polluted
52
How much money did the WB give to Kazakhstan for the Kok-Aral dam?
$85 million
53
What are some causes of water and energy insecurity in China?
• South China is home to the Yangtze River which is the worlds 3rd largest river • north China is semi arid and summer monsoons weaken before reaching it = very dry region at times • Beijing in north eastern area has 35% of population, 40% of arable land, yet only 7% of the water.
54
Three gorges dam info
• cost $39 billion • 22500 megawatt capacity • funded by the gov but also WB
55
Disadvantages of the three gorges dam?
• 1.3 million people relocated - many left homeless • 632km2 area flooded - 140 towns, 1500 factories • 265million gallons of sewage per year- poor quality water • several species such as river dolphin threatened • decomposing veg produced methane.
56
Advantages of three gorges dam?
• reduced emissions from coal - 10% of all china’s energy • regulates river flow - protects Jianjang from floods • makes cargo shipping easier.
57
South North project overview
- purpose is to transport water from large rivers in south to northern areas. • Started in 2005 • was expected to take 50 years • costs around $100 billion • includes 3 canals that run 1300 km • transfer a total of 44.8 billion m3 of water per year.
58
Disadvantages of South North project
• 345,000 people relocated • 3500 companies shut down • there are concerns that too much water will be drained from the south • will submerge 370km2 of land
59
Advantages of South North project
• Beijing gets 75% of its water from the south • has stimulated economic development in Beijing • addressed water shortages
60
What was the purpose of the Turkey GAP project?
• aims to construct 22 dams, 19 hydroelectric power plants, and 2 water transfer tunnels in Anatolia (a region that experiences drought) • will provide irrigation for 1.7 million hectares • stop out migration of young people from Anatolia • help Anatolian economy grow by 400% • grow Turkish economy by 12%
61
Who are the key players within the Turkey GAP project?
• turkey gov • Iraq gov • local residents • Syria gov • religious groups with ties to area
62
What is a potential international conflict over the Turkey GAP project?
Iraq was worried that Turkey would have control over the flow of rivers Tigris and Syria worried they have control over the river Euphrates • also Mesopotamian marshes rely on the flow of the rivers = people in those areas will be negatively affected.
63
What is a domestic conflict that could arise from the Turkey GAP project.
• Hasankeyf will be destroyed so archaeologists don’t want that - 12,000 years old. • also new town being built is expensive to move into for the residents
64
How much do houses in the new Hasankeyf cost?
180,000 Lira
65
What are some causes of water insecurity in Israel?
• semi arid region • limited natural freshwater sources • rising population • over abstraction • agricultural demand
66
How much did the Sorek desalination plant cost?
$400m
67
How much potable water can the Sorek Desalination plant produce per day
624,000m3
68
How many people can the Sorek Desalination plant supply
1.2-1.5 million - 20% of demand
69
What are the disadvantages of the Sorek Desalination plant
• high energy consumption • produces Brine (salty waste) which can damage local marine wildlife • geopolitical dependency - a country that depends on desalination is dependant on stable electricity • wildlife gets caught in water extraction such as fish and sharks
70
What are the advantages of the Sorek Desalination plant
• huge water supply capacity • ensures water security for a region with limited freshwater • reliable regardless of climate • supports agriculture and urban growth • 80% of Israel’s water is desalinated
71
Why are Desalination plants considered better than dams and water transfer?
• Cost of desalination is decreasing due to technological developments • does not require any land to be lost = no one needs relocating
72
How much would the Aral Sea restoration cost?
$87 million - world bank
73
What are the 4 taps in Singapore?
• Rain collection • Virtual water imports eg from Malaysia • recycled water - NEWater • Desalination
74
How much of Singapore’s water demand is covered by desalination and NEWater?
NEWater - 30% Desalination - 25%
75
Where is smart irrigation implemented?
Israel - drip systems allow water to slowly drip to plants’ roots through a system of valves and pipes - reducing wastage and evaporation.
76
What is ASR?
Aquifer Storage and Restoration
77
Where is ASR used most noticeably?
Florida, Saudi Arabia
78
How may ASR systems are there in Florida?
30
79
How does ASR work?
• Recharge (Injection) Source Water: During wet seasons or periods of low demand, excess surface water (from rivers, lakes, or treated wastewater/stormwater runoff) is collected. • Treatment: The water is pre-treated to remove particulates, balance mineral content, and meet water quality standards (e.g., drinking water standards if intended for future potable use) to prevent clogging the wells or degrading native groundwater quality. • Injection: The treated water is then pumped down one or more specialized injection wells into a suitable underground aquifer. The well often doubles as an extraction well. In confined aquifers, the water forms a "bubble" or "lens" within the native groundwater, displacing it. • Storage The injected water is stored underground, sometimes for months or years, creating a reserve for dry periods. A significant advantage of underground storage is that it prevents water loss from evaporation, which is a major issue for surface reservoirs. It is also naturally protected from contamination and temperature fluctuations. • Recovery During droughts or times of peak demand, the process is reversed. The stored water is pumped back to the surface using the same wells (or separate extraction wells in an Aquifer Storage, Transfer, and Recovery system). The recovered water may undergo final treatment or disinfection as needed before being distributed for use in irrigation, industrial needs, or as a public water supply.
80
How can the River Nile be used to argue that transboundary rivers increase conflict potential?
• Nile flows through 11 countries, creating competing demands • Upstream development threatens downstream dependency Exam judgement: The Nile shows how unequal power and dependency heighten conflict risk.
81
How can Egypt’s position on the Nile be used to argue that physical geography shapes political power?
• Egypt is downstream and heavily dependent on Nile water • Flat, arid environment → limited alternatives Exam angle: Physical dependence increases political sensitivity and defensiveness.
82
How can the GERD (Grand Ethiopian Renaissance Dam) be used to argue that development can cause transboundary tension?
• Ethiopia prioritises economic development and HEP • Egypt fears reduced water flow and food insecurity Judgement phrase: “Development upstream creates perceived insecurity downstream.”
83
How can the Nile Basin Initiative (NBI) be used to argue that cooperation is possible?
• Encourages shared data, dialogue, and long-term planning • Involves all basin countries Evaluation: Cooperation exists, but lacks legal enforcement, limiting effectiveness.
84
How can the Nile be used to argue that water conflict is more likely in LIC/NEE regions?
• Rapid population growth • High reliance on agriculture • Limited water infrastructure Exam judgement: Socioeconomic pressure amplifies physical scarcity.
85
How can the Colorado River be used to argue that conflict can occur even in developed regions?
• River shared between 7 US states + Mexico • Over-allocation and long-term drought Exam angle: Wealth does not prevent scarcity — it just delays consequences.
86
How can over-allocation of the Colorado River support arguments about mismanagement?
• Water allocations agreed during unusually wet period • Modern demand exceeds supply Judgement phrase: “Political agreements ignored environmental reality.”
87
How can climate change be used to explain increasing stress on the Colorado River?
• Reduced snowfall in Rocky Mountains • Higher evaporation rates Exam use: Climate change intensifies existing management failures.
88
How can US–Mexico relations over the Colorado River be used to argue inequality in transboundary agreements?
• USA controls most upstream infrastructure • Mexico receives lower-quality, less reliable water Judgement: Power imbalance shapes water access more than need.
89
How can the Colorado River Compact be used to argue cooperation has limits?
• Provided stability for decades • Now outdated due to climate change and population growth Exam angle: Cooperation must evolve to remain effective.
90
How may countries does the Nile flow through?
11
91
What percentage of Egypt’s water is from the Nile?
95%
92
When was the grand Ethiopian renaissance damn construction started
2011
93
What is the GERD mainly used for?
HEP - hydro electric power
94
How may US states depend on the Colorado river?
7
95
How many people rely on the Colorado river for water?
40million+
96
By how much has the average Colorado River flow decreased since 1990?
20%
97
What percentage of Colorado rivers water is used for agriculture
70%
98
When was the Colorado compact signed? What did it do?
1922 Allocated fair shares of water to the 7 states and Mexico - now out of date
99
How much has water storage in lakes Powell and Mead decreased by?
Water storage was at 43% in 2016
100
What org manages cooperation on the Nile?
Nile Basin Initiative (NBI)
101
How much water does California take from Colorado river?
20% more than its allocation
102
Why may tensions over the Nile have decreased?
China’s involvement in places such as Ethiopia has decreased tensions as they are a powerful nation
103
How many people relocated due to three gorges damn
• 1.3 million people relocated - many left homeless
104
How much land flooded due to three gorges damn? How many towns flooded?
• 632km2 area flooded - 140 towns, 1500 factories
105
How much water does the South north project transfer?
• transfer a total of 44.8 billion m3 of water per year.
106
How much did the South north project cost?
• costs around $100 billion
107
How much water is recycled by trees in the hydrological cycle?
- water cycling: 75% of intercepted water is returned to atmosphere by EVT, reduces to 25% when trees are reduced.
108
How much power can the illisu dam generate?
1,200 MW
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