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A Level Edexcel Geography BRM > Water EQ2 > Flashcards

Water EQ2 Flashcards

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1
Q

What is the definition of a drought?

A

A shortfall or deficiency of water over an extended time period

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2
Q

What are the three major types of drought?

A
  • meteorological drought
  • agricultural drought
  • hydrological drought
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3
Q

What is a meteorological drought?

A

Shortfalls in precipitation as a result of short terms variability within the longer terms average total.

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4
Q

What are the causes of a meteorological drought?

A
  • natural variation in atmospheric conditions
  • desiccation caused by deforestation
  • El Niño events (ENSO cycle)
  • climate changes
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5
Q

What are the features and impacts of a meteorological drought?

A

Features
- low precipitation
- high temps
- strong wind
Impacts
- loss of soil moisture
- supply of irrigation water decline

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6
Q

What is a hydrological drought?

A

Associated with reduced stream flow and groundwater levels, which decrease sue to reduced precipitation and high evaporation rates.

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7
Q

What causes a hydrological drought?

A
  • reduced precipitation inputs
    -high evaporation rates
  • ENSO cycles
  • climate change
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8
Q

What are the conditions during a El Niño event and how do they led to drought?

A

In an El Niño event trade winds are slackened or reversed reversing the air circulation loop.
This results in the cool water is replaced by warm water upwelling in Peru and the warmer water in Australia replace by cool water. This triggers a change in precipitation patterns throughout the world. The warmer upwelling of water lead to high rates of evaporation (lowering water table) but also creating more moist air and therefor changes in precipitation levels E.g failure in monsoon rains in India.

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9
Q

What’s are the conditions in a La Niña event and how do they led of drought?

A

La Niña event are associated with a exaggerated version of a normal years with a very strong Walker loop. It create drought due to the build up of cool water in the tropical part of the pacific.

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10
Q

What is a famine drought?

A

A humanitarian crisis in which the widespread failure of agriculture systems lead to food shortages and famines with massive socioeconomic and environmental impacts.

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11
Q

What is agricultural drought?

A

When rainfall deficiency from a meteorological drought leads to deficiency of soil moisture and soil water availability having a knock of effect on plant growth.

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12
Q

How does human activity has led to droughts?

A

The contribution of human activity such as
- deforestation (transpiration)
- urbanisation (Over extraction due to population growth)
- climate change
Do not cause drought but can enhance the effects and impacts acting like a positive feedback loop.

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13
Q

How has human influences made drought conditions more severe in the Sahel?

A

The main physical cause of drought in the Sahel region is the changing rainfall patterns that are very unreliable and semi arid conditions.
Human factors act like a feedback loop enhancing the impacts through the over extraction of surface and ground water due to
- population growth
- over grazing (destroying veg cover)
- deforestation (fuel wood)
Causing severe desertification.

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14
Q

droughts in Australia

A

Drought is a recurrent feature in Australia which are becoming more severe and frequent. The physical factors are El Niño crewing rainfall deficiency’s.
The big dry in 2006 is an example of a severe drought creating several impacts
- aquifers fell to 40% of their capacity
- completions over water between urban dwellers and farmers
Australia has managed their droughts by carful water management schemes, large scale grey water recycling and desalination plants.

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15
Q

What are the main ecosystems effected by droughts?

A
  • wetland
  • forest stress
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16
Q

What is a wetland and why are they valuable?

A

A wetland is a are4s covered or saturated with water, they cover 10% of the earths surfaces and are extremely valuable as
- act as temporary water stores
- recharging aquifers
- very high biological productively supporting diverse food webs (feeding sites for migrating birds)
- filters and maintain water quality (trapping pollutants)

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17
Q

How do droughts affect wetlands?

A

Less precipitation there will be less interception, infiltration and percolation causing the vegetation to become stressed and the water table to fall due to increased evaporation. This will reduce the valuable functions performed from the wetlands.

18
Q

How are forest ecosystems impacted in a drought?

A

Drought not only cause direct physical damage to forest through the starvation of water but also increases the susceptibility of lines and firs to fungal diseases increasing tree mortality. As well as this there is and increased threat of forest fires this both destroy habitats and decrease carbon stores. Reduces there role in the hydrological cycle (interception and transpiration).

19
Q

What is ecological resistance?

A

The capacity of an eco systems to withstand and recover from a natural event or some forms of human disturbance.

20
Q

What are the meteorological causes of flooding?

A
  • intense storms (flash flooding)
  • prolonged heavy rainfall (Asian monsoon or deep depression across the UK)
  • rapid snowmelt or jokulhaulps.(Siberia)
21
Q

What is the definition of flooding?

A

A surplus within the hydrological cycle leading to high flows of water in a drainage basin. Flooding occurs when the amount of discharge causes a body of water to overflow its channels and submerge the surrounding land.

22
Q

Why is Bangladesh particularly flood prone?

A
  • land consisting of floodplain and deltas build up by major rivers such as the Ganges
  • meltwater from the Himalayas
  • summer monsoons
  • prone to storm surges
23
Q

What physical factors increase the risk of flooding?

A
  • low lying areas with impermeable surfaces
  • impermeable rocks
  • vegetation amount
  • high gradient slopes
  • shallow soil depth
24
Q

What human actions increase the risk of flooding?

A
  • urbanisation
  • damn building
  • downslope ploughing
  • river mismanagement
  • deforestation
25
Q

How does urbanisation increase flood risk?

A
  • creation of impermeable surfaces
  • drainage systems speeding up the movement of water into rivers ect
  • changing land use to agricultural development
  • higher amounts of interception from roofing, feeding more water into drainage system
  • bridge support build into rivers
    Also tends to be concentrated in lower lying lands within a drainage basins meaning the natural and human factors coincide enhancing the frequency and magnitude of flood risk.
26
Q

How does river mismanagement increase flood risk?

A

Channelisation > displaces the river downstream, leaving areas overwhelmed with the Alina of discharge
Damns > block the flow of sediment filling the reservoir with silt crewing increased river bed erosion downstream
Embankments > they can fails when flood exceed capacity making the scale of loading much greater.

27
Q

What are the socio-economic impacts of flooding?

A
  • death and injury
  • spread of water borne diseases
  • damage to property
  • disruptions of transport and communications (Cumbria, many people endured power shortages for up to three days)
  • destruction of crops and loads of supply’s
  • disturbance of everyday life such as work and education
    e.g. In Carlisle, the McVities biscuits FaceTime was flooded leading to a temporary loss of over 1000 jobs
  • drops in tourism (Cumbria)
28
Q

What are the environmental impacts of flooding positives?

A

In many natural ecosystems,
flooding play an important in maintaining key functions and biodiversity
- recharged groundwater stores
- increased connectivity between aquatic habitats
- soil replenishment
- can trigger breeding, migration and dispersal

29
Q

What’s are the negative environmental impacts of flooding?

A

Most ecosystem have a degree of ecological resilience that can cope with the effects of moderate flooding. Where the environmental has been degraded by human activities the negative impacts are more evident.
- removal of soil and sediment by waters containing pesticides can led to water eutrophication
- lead to pollution of water sources form urban lands (chemicals and heavy metal)
- disease carried by flood water can weaken or kill trees

30
Q

What’s are the main points of flooding in the UK 2016?

A

During the 2016 floods the UK, large areas of land received more than twice the average amounts of rainfall for that time of the year abusing severe impacts, notably in Cumbria (Carlisle and Cockermouth)
- homes damaged
- water supplies and energy supplies cut off for up to three days
- McVities temporary job loss for 1000 employees.

31
Q

How does climate change affect the input into a hydrological cycle?

A
  • warmer atmosphere has greater water holding capacity
  • expected that rainfall will increase in intensity rather than total amount
  • areas experiencing precipitation will increase to include the tropics and high latitude areas
  • areas of precipitation will decrease between 10o and 30o north and south of equator
  • more precipitation falling as rain rather than snow in northern regions
  • increase in length and frequencies of heats waves leading to drought
32
Q

How is climates change effecting outputs in a hydrological cycle?

A
  • higher temps are leading to higher rates of evaporation notably over large areas of Asia and North America
  • transpiration rates are linked to amount of vegetation which is directly links to soil moisture (to little or too much soil moisture can relate changes in transpiration?
33
Q

How is climate changes affecting surface runoff and steam flow?

A

With more climate extreme there will be an increase in hydrological extremes with more
- low flows (droughts)
- high flows (floods)
With and accelerated hydrological cycle with more intense rainfall will increase surface runoff and reduce infiltration.

34
Q

How is climate changes affecting Groundwater flow?

A

Evidence with ground water flow is limited due to human over abstracting meaning no direct link can be made between the two.

35
Q

How is climate changes affecting reservoirs, lake and wetland storage?

A
  • changes to wetland storages cannot be conclusively linked to climate change (high temps may been higher evaporation and lower water tables)
  • as temperature is increasing water storage is decreasing (evaporation rates)
36
Q

How is climate changes affecting soil moisture levels?

A

Evidence is quite ambiguous as many factors can affect soil moisture.
- little change with higher precipitation and evaporation cancelling each other out
- if precipitation levels are increasing soil moisture is also likely to increase (c > human factors meaning more surface runoff)

37
Q

How is climate changes affecting Permafrost?

A

Changes in climates at high latitude is leading to permafrost degradation in northern areas due to
- higher temperatures
- more precipitation falling as rain rather than snow
this can create a positive feedback loop.

38
Q

How is climate changes affecting snow?

A
  • decreasing length of snow covered seasons
  • spring me,t starting earlier
  • decrease in temporary stores
  • decrease in precipitation falling as snow
39
Q

How is climate changes affecting glacier ice?

A
  • strong evidence of glacier retreat and thinning since 1970s due to higher temps.
  • less accumulation as precipitation falling as rain
  • a decreasing store
40
Q

What are the problems with forecasting possible changes to the hydrological cycle?

A
  • hard to distinguish between the impacts of long terms climate change and short term oscillation associated with ENSO cycle
  • ENSO cycles cause extreme flooding and extreme droughts in different parts of the world)
41
Q

Why does uncertainty arise over the change to hydrological cycle and water supply?

A

Uncertainty can arise because modern scientific research are unable to make confident forecasts about the future availability of waters. As well as unknowns in possible advances in water technology, population growths and global development.

42
Q

What are the factors leading to diminishing water supply and increased uncertainty?

A
  • increase in temperature lead to greater evaporation rates from surface water and reservoirs.
  • greater rates of evapotranspiration
  • impact of oscillations (ENSO) unreliable rainfall patterns
  • increased intensity and frequency of droughts (impacting food supply’s
  • more frequent monsoon and cyclone events
  • depletion of aquifers and groundwater
  • loss of snow and glaciers threatening communities and ecosystems

A Level Edexcel Geography BRM (29 decks)

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