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Water Flashcards

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1
Q

What is the hydrological cycle?

A
  • A conceptual model that can be evaluated at a number of levels of complexity for different purposes
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2
Q

How much water is in the atmosphere?

A
  • Water in the atmosphere is a tiny proportion compared to that in the ocean.
  • Potentially 13,000 km3 water- need to have a vague idea of this figure in order to manage water resources for human activities like agriculture, domestic etc
  • Direct measure of water in the atmosphere- there is limited spatial and temporal coverage
  • Indirect measurement- repeat survey (daily at 250m)
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3
Q

What does Charline (1992) say about water estimates?

A
  • Underground water may be incorrect by a factor of 2 to 4.
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4
Q

What is unusual about extreme weather conditions in America at the moment?

A
  • There have been a higher frequency of such occurrences.
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5
Q

What is an element characterised by?

A
  • The number of protons in it
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6
Q

What can change in an element?

A
  • May have different numbers of neutrons which changes the elements atomic weights.
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7
Q

What does mass spectrometry allow us to do?

A
  • Analyse the isotopic composition of materials
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8
Q

How are oxygen isotopes usually characterised?

A
  • Using the ratio of 18O to 16O
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9
Q

How are hydrogen isotopes usually characterised?

A
  • Using the ratio of 2H to 1H
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10
Q

What do 18O to 16O and H2 and H1 have in common?

A
  • They are all considered to be stable isotopes

- 3H is occasionally used as a tracer because it decays radioactively.

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11
Q

In the hydrological cycle why do the elements of oxygen and hydrogen end up having successive fractionation?

A
  • The isotopes have different vapour pressures

- e.g. When water evaporates from the ocean the oxygen elements are at -12% vapour while the hydrogen is at -87%

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12
Q

Describe isotopes in UK precipitation

A
  • Great variability in oxygen 18 and 16 at daily and seasonal scales.
  • This can be partly explained by the evolution of storms and temperature variations but also because of the Standard Mean Ocean Water.
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13
Q

What are the oxygen elements at in SMOW?

A
  • 0%
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14
Q

What does SMOW stand for?

A
  • Standard Mean Ocean Water
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15
Q

What is the equation of continuity or mass conservation?

A
  • Flow in - store- flow out
  • If system is at a steady state, then flow in = flow out
  • So store/flow in = store/ flow out = residence or turnover time
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16
Q

How does water get back into the atmosphere?

A
  • Evapotranspiration is a complex process involving net radiation, soil heat flux, vapour pressure, deficit of air, air density and specific heat, vapour pressure as a function of temperature, surface and aerodynamic resistances and relationship between partial pressure of water in air to air temperature.
  • Difficult to measure
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17
Q

What does Charney (1975) say about albedo?

A
  • Changes in albedo as a function of vegetation growth has a positive feedback on rainfall in the Sahel.
  • Vegetation has lower albedo, thus leading to more surface heating, stronger land-ocean temperature ocean gradients, which in turn enhance monsoonal circulation in the tropics.
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18
Q

Who proved that Charney (1975) was wrong about his theory on albedo?

A
  • Wendell and Easton (1983)
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19
Q

What is the alternative to Charney’s theory about albedo?

A
  • Entekhabi (1992) suggests that the reprecipitation of moisture that is evapotranspired from vegetation is more likely to lead to feedback at a regional level.
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20
Q

What is the difficulty with measuring global-scale processes?

A
  • They’re difficult to visualise and their measurement is not straightforward.
  • Recognising and dealing with uncertainty is a fundamental part of the analysis of the the earths systems
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21
Q

What are some of the ways that are being used to predict global scale processes?

A
  • Satellite, isotopic and other advanced techniques

- Evaluate the stores and fluxes of water at catchment to global scales.

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22
Q

What is the hydrological cycle a cycle of?

A
  • Cycling of water of 3 major reservoirs

- Oceans- atmosphere- atmosphere

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23
Q

What are the different types of water on earth?

A
  • 97% water is saltwater
  • 3% water is saltwater
  • Volume of water in the atmosphere is about 0.001 percent of that on the whole earth
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24
Q

In order from highest to lowest which state conversions use the most energy?

A
  • Conversion from gas to solid vv (2.83MJ/Kg)
  • Conversion from gas to liquid vv (2.5Mj/Kg)
  • Conversion from solid to liquid vv (0.33Mj/Kg)
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25
Q

How do temperature and the atmosphere interact?

A
  • The atmosphere can only absorb so much water
  • This is strongly linked to and affected by the temperature
  • Warmer temperature means that more can be absorbed.
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26
Q

What is absolute humidity?

A
  • Term used to describe the maximum amount of vapour that can be absorbed by the atmosphere.
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27
Q

Describe how the relative humidity changes with temperature increase?

A
  • 10 degrees- water vapour- 100% relative humidity
  • 20 degrees- water vapour- 52% relative humidity
  • 30 degrees- water vapour- 28% relative humidity
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28
Q

Describe the potential (PET) and actual evapotranspiration (AET)

A
  • Transpiration is a process by which plants lose water through stomata
  • AET is the amount actually evaporated
  • PET is the amount that would be evaporated if there was no limit of water availability
  • PET often referred to as the climatic demand
  • Relative humidity varies with temperature and therefore isn’t a good measure of water in the atmosphere.
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29
Q

How can we explain the difference between potential and actual evapotranspiration?

A
  • Desert is very hot but lacks water availability- evapotranspiration cannot occur
  • Therefore it has a very high PET but a low AET
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30
Q

What does the term net radiation refer to?

A
  • Available for heating or evaporation
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31
Q

What is latent heat?

A
  • Measure of how much energy is consumed in evaporation
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32
Q

Where are latent heat flows strongest?

A
  • Highest in tropics because of high short wave radiation

- Also in places near the equator where the ocean is very warm

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33
Q

Describe the humidity gradient characteristics which lead to high evaporation

A
  • Saturated surface (high humidity)
  • Steep moisture gradient
  • Dry atmosphere (low humidity)
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34
Q

Describe the humidity gradient characteristics which lead to little or no evaporation

A
  • Saturated surface (high humidity)
  • Little or no moisture gradient
  • Saturated atmosphere (high humidity)
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35
Q

Describe the wind characteristics which lead to high evaporation

A
  • Saturated surface (high humidity)
  • Strong wind/turbulence
  • Moisture carried away- atmospheric humidity lowered and humidity gradient restored.
  • Saturated atmosphere (high humidity)
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36
Q

Describe the wind characteristics which lead to little or no evaporation

A
  • Saturated surface (high humidity)
  • Weak wind/ turbulence
  • Moisture not carried away- weak or no humidity gradient remains
  • Saturated atmosphere (high humidity)
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37
Q

What is condensation?

A
  • Direct cause of all precipitation
  • Airmass mixing- can be both vertical and horizontal
  • Increased water content
  • Dynamic (adiabatic) cooling- Adiabatic process, cooling/warming due to expansion/compression, no heat added or subtracted
  • Occurs when a moist parcel of atmosphere cools
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38
Q

Describe the process of adiabatic temp changes

A

1) Vertical displacement
2) Lower pressure
3) Expansion
4) Cooling

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39
Q

Describe a situation with a dry adiabatic lapse rate (10 degrees/km)

A
  • Rising air parcel expands and cools

- Sinking air parcel is compressed and warms

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40
Q

What is the dew point?

A

The point at which moisture will condense.

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41
Q

Give an example of the dew point temperature

A

If air was at 32 degrees with ony 1kg/kg of moisture would need to cool it to 2 degrees for condensation to occur.
- In this situation, 2 degrees would be the so called dew point temperature

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42
Q

What are the 4 main causes of uplift?

A
  • Convective lifting
  • Orographic lifting
  • Frontal wedging
  • Convergence
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43
Q

What is cloud like at the equator?

A

-condensation caused by convergence of North and South water vapour

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44
Q

Describe water vapour trends in g kg -1

A
  • Trends in column integrated water vapour occur over ocean surfaces
  • Global annual average anomalies in column integrated water vapour averaged over ocean surfaces. Anomalies are relative to the 1988-2007 average.
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45
Q

What is a weakness of relative humidity

A
  • Unreliable measure of absolute atmospheric moisture levels.
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46
Q

What determines evaporation?

A
  • Temperature, radiation, vertical humidity gradient and windspeed
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47
Q

What do global patterns of moisture atmosphere do?

A
  • They reflect distribution of latent heat flux
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48
Q

What is the modern ideal of the British landscape?

A
  • Images of open grassy and green landscape
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49
Q

What are some of the divides in the UK?

A
  • North-South divide associated with social differences

- In terms of physical processes, the UK has a east-west divide which also applies to geology

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50
Q

What is the infiltration excess overland flow?

A
  • Rainfall intensity and Robert Horton model (1933)
  • Rainfall intensity = i, Infiltration rate= f, Time= t
  • Infiltration rate decreases over time as ground becomes more saturated.
    0= i-f
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51
Q

How did people think about flow until the 1960s?

A
  • Rainfall intensity and Robert Horton model
  • Variable source areas idea developed during the 70s and 80s which said that different catchment areas generate different amounts of overland flow.
  • Meanwhile Darcy’s law states that as mean pressure increases, mean flow increases in a direct line.
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52
Q

What can affect flow?

A
  • Changes in vegetation hugely affects what water goes back into the atmosphere and how much water becomes overland flow etc
  • Linear relationship between change in forest cover and change in water yield. The amount of change can be hugely variable.
  • There is a range of ways that sediment can be transported on hillslopes including creep, mass movement, intersill erosion, sill erosion, splash
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53
Q

What does the extent and nature of a flood depend on?

A
  • How much water gets into a channel from these sources, and how quickly it moves from one part of a catchment to another.
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54
Q

How does water flow through unsaturated soils?

A
  • Richards equation
  • Flux is a function of the pressure head (or gradient in potential energy), suction and the hydraulic conof the pductivity (which changes with moisture content).
  • Little or no throughflow
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55
Q

How does water flow through saturated soils?

A
  • Darcys law
  • Flux is a function of the pressure head (or gradient in potential energy), and the saturated hydraulic conductivity.
  • More, faster throughflow
56
Q

What are some fast flows through the soil?

A
  • Macropore flow

- Pipe flow

57
Q

Describe macropore flow

A
  • Due to root or animal activity e.g. crane fly larvae and earthworms
58
Q

Describe pipeflow

A
  • Often occur naturally in peat or marl soils

- Artificial pipes are commonly found in agricultural soils in the UK

59
Q

What are the effects of catchment characteristics on controlling water flows into channels

A

1) Diffuse flows on hillslopes flow faster as the get deeper. This results in more rapid run off as the magnitude of run off increases.
2) They flow faster when the slope is steeper
3) They flow faster when the bed surface is smoother or less rough. e.g. runoff is more rapid in urban areas.
4) Under all these conditions (rills and gullies) will start to form which are more efficient at moving water.

60
Q

Name two different types of flow?

A
  • Diffuse flow (slower)

- Concentrated flow

61
Q

What are the two critical processes in drainage networks?

A

1) Flow accumulation- The process of accumulation leads to increases in flood wave peaks.
2) Flow attenuation- The process of attenuation leads to decreases in flood wave peaks.

62
Q

What is attenuation?

A
  • The opposite of conveyance
63
Q

What happens to discharge downstream?

A
  • It increases as flow accumulation also increases.
64
Q

When did the Boscastle floods happen?

A
  • 2004

- 185-200mm in 24hr (mostly in 5hrs)

65
Q

How might flow attenuation occur?

A
  • A single channel with no inflow would result in attenuation.
  • This is when downstream movement of water is slowed due to secondary circulation, friction, storage etc.
66
Q

What factors are critical in understanding catchment response to a storm event?

A

1) Timing

2) Location

67
Q

What factors cause attenuation?

A

1) Different timings of sub-catchment response
2) Transfer of water to floodplains
3) Momentum/ energy loss within the water wave

68
Q

How do humans try to use attenuation to their advantage?

A
  • May be introduced immediately upstream of urban areas to take the ‘tops’ of flood waves.
  • May also be used further upstream to slow flood waves
69
Q

What is the problem with using attenuation strategically.

A
  • If you defend an area by stopping water going onto the floodplain you locally reduce attenuation.
  • Has the effect of increasing flood risk downstream
70
Q

What are some arguments for accumulation over attenuation?

A
  • ‘the purpose of waterways is to get rid of water- Owen Paterson, Secretary of state for environment
71
Q

What are some arguments for attenuation over accumulations?

A
  • ‘Increased dredging of the Somerset levels would not have prevented the recent widespread flooding- Dr Kate Marks, EA flood-risk manager
72
Q

What are the pros of dredging?

A
  • Improve land drainage and flow conveyance
  • Improve navigation
  • Economic use for sand and gravel extraction
73
Q

What are the cons of dredging?

A
  • Flow continuity/mass balance- floodplains cover large areas so channels would need to be much deeper/wider to allow flow passage.
  • Increases subsequent erosion by destabilising banks
  • Disturbance of ecosystems.
    Cost:
  • Scour and fill- need to repeat after every major flood
  • Stabilisation of bridges etc
  • Where to put dredged silt (contaminated)
74
Q

How are humans making ourselves more vulnerable to flooding?

A

1) Urbanisation- use of flood-risk land
2) Urban impacts- smooth surfaces
3) Infrastructure- services we depend on e.g. gas
4) Buildings and contents- more things to repair
5) Social impacts- changing response of society

75
Q

Give some specific infrastructure impacts of flooding in Britain

A
  • 2007 floods
  • 55,000 properties flooded, 7,000 people rescued, 3 people died, largest loss of essential services
  • Ranked as most expensive in the world in 2007
76
Q

Describe infrastructure impacts of flooding in worldwide

A
  • 200 major floods in 2007
  • 180 million people affected
  • 8000 deaths
  • £40 billion in damage
77
Q

Describe how buildings and contents have become more vulnerable to flooding?

A
  • Increase in damages at all flood depths from 1990-2005
  • Costs of damage to goods increased faster than damage to buildings
  • Johnson et al (2007, Area)
78
Q

What do we need to understand in order to appreciate flooding as a complex issue?

A
  • Social and cultural factors

- These have knock on impacts

79
Q

What is a key term in flooding?

A
  • Vulnerability
80
Q

What is drought?

A
  • Meteorologists would say it is below normal precipitation
  • Hydrologist- below- normal water supplies
  • Farmer- insufficient water to grow a crop
  • Residents- socioeconomic
81
Q

What is a meteorological drought?

A
  • What does below-normal precipitation mean?
  • In the UK, it is formally 15 consecutive days with less than 0.2 mm precipitation or les than 50% rainfall in 3 months or 15% lower than average over two years.
82
Q

How are standardised deviations used in droughts?

A
  • In arid regions, the UK classification would be fairly meaningless.
  • More often used to compare the long-term deviation from the mean.
83
Q

What is a hydrological drought?

A
  • Looking at a hydrological drought we can evaluate whether there was any prolonged differences from the mean for different parts of the hydrological cycle.
  • River flows, reservoir and lake levels and groundwater levels are particularly important because of their role in supplying drinking water.
84
Q

What are the biotic effects of drying?

A
  • Will depend on how and when drying occurs- importance of connectivity
  • Trapping of animals in pools- duration of drying important, ultimately- death
  • Differential mobility of fish, invertebrates etc can lead to imbalances in food chains
  • Persistent drying can lead to isolation and genetic divergence.
  • Pools become hotter and have higher organic matter concentrations, which can be lethal to fish and other organisms.
85
Q

What is the Palmer drought- Severity Index?

A
  • Wayne Palmer developed his index in 1965 as a way of comparing drought across the different climates of the UK.
  • The index uses a simplified representation of the hydrological cycle- ie uses an understanding or process- to produce a standardised range of values.
86
Q

Give an example of a place prone to extreme drought

A

California

87
Q

What is an agricultural drought?

A
  • Reflects lack of availability of soil moisture for crops of a specific type.
  • May still occur even if there is no meteorological drought.
  • Different crops have different water requirements- crop dependent.
  • ## Plants can have different water requirements at different points in their life cycle- relative to current needs and not conditions
88
Q

How does the stomata of a plant help it adapt to drought conditions?

A
  • Stoma (plural of stomata) must open to allow Co2 to enter.
  • Mesophyll cells saturated (85-90%) to allow C02 capture and photosynthesis.
  • Vapour pressure deficit between leaf and atmosphere- high transpiration losses in drylands.
89
Q

How is crassulacean acid metabolism used as a tool for adaptation in plants?

A
  • As C4 cycle at night (stomata closed to conserve water) producing CO2, stored in leaves which is converted during the day using a similar mechanism to C3, then conversion to glucose, with feedback producing PEP for the C4 cycle.
90
Q

What is the concept of socio-economic drought?

A
  • Reflects the ability of water-supply systems to meet demand for water at a particular time.
  • Demand can be both in terms of quality and quantity.
91
Q

What relates to quality in a drought/

A 
Drinking water:
- Bacterial content
- Chemical content
- PH
Irrigation water:
- Salinity
- Other chemicals
92
Q

What relates to quantity in a drought?

A
  • Drinking water
  • Water used to grow food: Rainfall, irrigation
  • Household use
  • Industrial use
  • Municipal use
93
Q

How can water quality be affected?

A
  • But not all problems are visible as sediment contamination.
  • Sources can be close by… or at a distance e.g. Chernobyl fallout, acidification of Scandinavia from W Europe industry.
  • In periods of droughts/drylands, effects of contamination can be exacerbated because there is less water to dilute the source.
  • A common problem is salinization of water in irrigated landscapes.
94
Q

What is salinization?

A
  • Globally 77 million hectares have been salinized to human activities.
  • 58% in irrigated areas
  • 20% of the world’s irrigated land is salt-affected.
  • Colorado basin and parts of Australia are particularly badly affected.
95
Q

What are the ways that people might manage water?

A

1) Managing demand- changing behaviours
2) Increasing supply- reservoirs, inter-basin water transfers
3) restricting supply- rationing
4) Legal approaches

96
Q

Describe water management at Owens lake?

A
  • Water was diverted to LA Aqueduct from 1913 and by 1926, the lake had dried completely.
  • Significantly dust emissions started, as aridity and saline conditions prevented vegetation from stabilizing surface.
  • But took until July 1998 for the Great Basin unified air pollution control district and the city of LA agreement to resolve the disputes and air pollution.
97
Q

What should we appreciate about the geography of an area?

A
  • History behind it
  • Feedbacks and extremes very important and relate to the scale of the problem.
  • Appreciate length of time scales in water and how it has formed the landscape.
98
Q

What was the Messinian Salinity Crisis in the Mediterranean?

A
  • Between about 6Ma and 5.3Ma, a slab of subduction get lithosphere broke off and started to create isostatic uplift in the area of the strait of Gibraltar
  • Uplift closed off at the Mediterranean from the Atlantic
  • Thus started a large scale natural experiment in evaporation as refilling from rivers was no longer able to keep up with the evaporative demand.
99
Q

How long would it take to balance evaporation with inflow from rivers to reach a balance with no sea-water input?

A
  • Meijer and Krijgsman (2005) said that freshwater input would be c6000 m3 a-1 using modern river flows as a first order approximation.
  • Drawdown of the Mediterranean would only have 5-8ka.
  • Salinity also increases dramatically over this time.
  • How long would it take for the Mediterranean to dry out?
100
Q

Describe Gibraltar falls?

A
  • Meijer and Krijgsman (2005) used a static model to suggest that refilling could occur in 2-3 ka.
  • Garcia- Castellanos et al (2009) looked at dynamic feedbacks in incision at the Gibraltar Sill and suggested that it would be possible to refill the entire basin in about two years.
101
Q

Why are events such as the Messinian Salinity crisis considered important events in understanding modern landscapes?

A

1) They change the boundary conditions for current landscape evolution
2) They produced basins filled with evaporites, marls or alluvial sediments that are weakly consolidated and thus erode very actively as badlands.
3) Show that high magnitude but low frequency events significantly change the behaviour of the landscape and that contingent events are important

102
Q

How are boundary conditions created?

A
  • Erosion at the edge of landscapes
103
Q

How do key water events change the boundary conditions for understanding current landscape evolution?

A
  • Rhone valley incised canyon of about 1000m and the Nile delta has an incised canyon of about 2500m in their deltas
  • These canyons extend back significantly into the interior as the rivers adjusted to the new base level
  • Pliocene and Quaternary channels have been refilling these canyons as a result of current base level.
  • Carving of the Gibraltar sill is deep enough to prevent Mediterranean being cut off during quaternary glaciation
104
Q

What are the badlands?

A
  • Difficult to travel across
  • Bumpy topography
  • Evaporites widely spread across the med.
  • South facing slopes devoid of vegetation with concave shape vice versa on the north
105
Q

What is significant to note about the Mediterranean Sea?

A
  • Landlocked
  • Sea ringed by mountains- Braudel
  • Connections to tectonics
  • Controls the regional climate
  • Airstreams are blocked by mountains with secondary streams within the med.
106
Q

What are the consequences of water deficit?

A
  • After a few days of water deficit, plants will begin to wilt
  • Generally plants will either grow in more hospitable climates or will adapt to live there.
107
Q

What adaptions might plants make to handle water deficit?

A
  • Having small or unusual leaves
  • Shedding leaves in times of water stress
  • Rolling leaves
  • Sun tracking
  • Having open canopies with non-overlapping leaves
  • Salt secretion
108
Q

What is the effect of patchy vegetation on runoff response?

A
  • Decreases significantly.
109
Q

What other consequences may long periods of water deficit lead to?

A
  • Long dry spells, convective rainfall and high temps and windy conditions can lead to high fire risk.
  • Areas of high biomass and vegetation more endangered
  • Fire is a very significant process in the med and dry lands
110
Q

What are the hydrological effects of fire?

A
  • Runoff rates increase for intense fires because particle size can change, soil aggregates be broken down and the development of hydrophobicity
  • Erosion rates change because of lack of structure in the soil, smaller particles, lack of vegetation canopy and roots in the soil.
111
Q

What are the effects of vegetation on water pathways and flow?

A
  • Intercepts rainfall before it has a chance to infiltrate
  • Modifies surface and soil characteristics so changes infiltration rate.
  • Controls transpiration of infiltrated water after infiltration
112
Q

How can different parts of plants affect flow?

A
  • Stemflow- can produce rapid flow to root crown
  • Litter- effects on infiltration and evaporation (mulch)
  • Roots- focus subsurface flows (speed and location)
113
Q

What factors effect transpiration (plant physiology)?

A

1) Stomatal cover
2) Seasonal growth
3) Growth stage
4) Canopy health

114
Q

What factors effect evaporation (local climate setting)?

A

1) Exposure and ventilation
2) Albedo
3) Seasonality

115
Q

What might different levels of evapotranspiration cause?

A
  • Big effect on vegetation
  • Lush or sparse growth
  • Turnbull et al (2010) Hydrological Proc
116
Q

What effects does vegetation have on sediment erosion, transport and deposition?

A
  • Changes raindrop size and distribution and thus splash erosion
  • Increases roughness so affects flow detachment and transport
  • Roots bind surface materials so that there is more cohesion
  • Litter affects aggregate stability
  • Tree-throw disturbs soil and promotes creep
  • Indirect effects via changes in soil-production rates
117
Q

What effect do animals have on water pathways and flow?

A
  • Burrowing reduces compaction and generates macropores

- Production of faecal matter increases aggregation and thus infiltration.

118
Q

What are the effects of animals on sediment erosion, transport and deposition?

A
  • Faecal matter affects aggregate stability and thus entrainment
  • Increases roughness so affects flow detachment and transport
  • Direct movement of material through burrowing and digging
  • Stabilisation through crusting
  • Indirect effects via changes in soil-production rates.
119
Q

What did the study by Neave and Abrahams (2001) on rainfall and discharge show?

A
  • Animal digging has a significant impact on runoff and sediment production
  • Sediment concentration was much higher with animals present and the discharge increased much more quickly but tapered off sooner
120
Q

What is key to understanding an issue?

A
  • Scale at which we look at it in both space and time.

-

121
Q

What is blue water?

A
  • Surface and groundwater
122
Q

What is green water?

A
  • From rainfall/in root zone
123
Q

What is grey water?-

A
  • Water contaminated by pollutants from various sources
124
Q

Is water scarce?

A
  • Fallenmark (1997) and Wallace (2000) suggest that the water requirement is 1000m3 per person per year.
  • Data shows that an animal based diet uses 5 times more water than a plant one.
125
Q

What are the problems with water and water requirement estimations?

A
  • Water will become stressed if the minimum amount of water per person is not available.
  • While it is said that 1000m3 per person per year is needed, current usage is over 1400m3 (Hoekstra and Mekonnen, 2012)
  • Map doesn’t account for the fact that the global average water use is over 1000m3
126
Q

What is interesting to observe about water usage by humans and plants?

A
  • Plants are actually more efficient at managing water

- Plants are more resilient to water shortages at an inter annual scale.

127
Q

Describe water efficiency in storage and conveyancing?

A
  • Can transfer water in pipelines rather than open aqueducts, but its difficult to cover large reservoirs
  • Colorado and California aqueducts
  • Drip irrigation in orange groves in Valencia.
128
Q

How can we increase water efficiency?

A
  • Reduce evaporation from soil
  • Reduce run off
  • Reduce drainage from the crop root zone
  • There are some very simple ways that we can store water
129
Q

What are some essential things which use up a lot of water?

A
  • FOOD- beef, tea and coffee particularly use large amounts of water
  • Our lifestyle choices make a huge difference in how much water is used
130
Q

Describe a water sustainability project?

A
  • Great man made river project, Libya
  • First phase took 7 years to build and was completed in 1991
  • Water pumped from aquifers 600-2000m below the surface
  • 4000km pipeline designed to carry 6.5m3 day.
  • Aim to irrigate 155k ha
  • Huge project, huge scale, considerable water loss, national scale much less sustainable than local use.
131
Q

What is fossil water?

A
  • We can date groundwater using different methods
  • If we are using a water source that is not being replenished that is unsustainable.
  • So if water is thousands to millions of years old in areas where recharge is currently zero, the water use is unsustainable.
132
Q

How is politics involved in water?

A
  • Examining water imports
  • USA and Australia are significant exporters have water.
  • While countries like Japan and Mexico are dependent on external sources- political implications for control of such a valuable resource.
133
Q

What are some of the needs for water?

A
  • Provisioning services- food supplies for people
  • Cultural services- recreation and aesthetic value
  • Supporting services- support food webs and biodiversity
  • Regulating services- regulation of climate via veg feedbacks
134
Q

Describe drought and climate change

A
  • Drought can change different ways as climate changes. Extreme temps might change if the mean increased, temp variability increased or the relative pattern of hot and cold conditions changed.
  • These changes will alter the patterns of hydrological, agricultural and socio-economic drought occurrence over the next century so that changes may be very spatially variable.
  • On top of these patterns, changes in rainfall extremes will change the occurrence of meteorological drought.
135
Q

How will water changes affect food?

A
  • Reduced water will damage wheat and crop production

- Global production estimated to fall by 6% for each 1 degree increase in climate

Physical Geography (5 decks)

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