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Geography - A LEVEL > Water balance and changes - P > Flashcards

Water balance and changes - P Flashcards

1
Q

what is a drainage basin

A

an area of land drained by a river and its tributaries

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2
Q

what is a catchment

A

the area of a drainage basin e.g. the amazons is 7 million km squared

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3
Q

what creates dynamic equilibrium

A

water continually entering and leaving a drainage basin

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4
Q

what is a river system

A

a river and its tributaries make up a river system also called a drainage basin/watershed

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5
Q

what is a watershed

A

includes the river, all its tributaries and any groundwater resources in the area

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6
Q

what is the river mouth

A

the end of a river - where it empties into another body of water like the ocean, lake etc.

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7
Q

what is the water balance

A

the balance between inputs and outputs in a drainage basin - usually shown on a graph

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8
Q

what is the equation for the water balance

A

P = Q + E +/- changes in storage
P - precipitation
Q - runoff
E - evapotranspiration

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9
Q

what does a watershed mark

A

the boundary between two separate drainage basins

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10
Q

are drainage basins open or closed systems

A

open systems - receive inputs and outputs

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11
Q

what happens to water in a drainage basin after precipitation

A

water will flow downstream from the source, tributaries will join together creating a confluence before flowing out to sea at the mouth

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12
Q

what are the 10 types of flowing

A

channel flow
surface runoff
infiltration
throughflow
percolation
interflow
groundwater flow
baseflow
throughfall
stemflow

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13
Q

what is interflow

A

when water travels through permeable rock above the water table

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14
Q

what is baseflow

A

when water feeds onto the channel through the banks and bed

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15
Q

how is water stored in the cycle; through interception

A

vegetation storage
surface storage
groundwater storage
channel storage

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16
Q

what are the outputs of water

A

evapotranspiration
evaporation
transpiration
runoff into the sea

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17
Q

what are the three factors that could affect the water balance (there are more than 3 but we only needed 3 examples)

A

temperature
human activity
rainfall

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18
Q

how could temperature affect the water balance

A

increases evaporation and transpiration in higher temperature.
decreases evaporation and transpiration in lower temperatures

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19
Q

how does human activity affect the water balance

A

may release fossil fuels so there are more nuclei for clouds to from around so increased precipitation

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20
Q

how could rainfall affect the water balance

A

more rainfall causes more inputs of water (precipitation)
less rainfall causes less inputs of water (precipitation)

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21
Q

what is a catchment

A

the area of land within a drainage basin which includes everything within it

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22
Q

what is river discharge

A

the volume of water passing a given point at a given time. Measured in cumecs (m**3/s)

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23
Q

what is the equation of discharge

A

discharge = cross sectional area x velocity

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24
Q

why is it important to monitor river discharge

A

can anticipate floods & shortages
detecting climatic and environmental change
allows the assessment and management of water resources, the design for water-related structures and flood warning schemes.

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25
what is a method of measuring river discharge
the float method
26
describe the steps of the float method
1. mark two points along the channel (this is the distance) 2. measure 3 depths and find the average (depth) 3. measure the rivers width (width) 4. fill a float bottle partially with water 5. drop bottle and start the timer stop the timer when it reaches the second observer. 6. repeat step 5 3 times and find the average (time) 7. determine flow: width x depth x (distance / time) x correction factor
27
what is a water budget
the annual balance between precipitation, runoff and evapotranspiration (inputs and outputs)
28
what is the equation for the water budget
P = Q + E P - precipitation Q - runoff E - evapotranspiration
29
what does a positive water budget mean
water surplus (inputs > outputs)
30
what does a negative water budget mean
water deficit (inputs < outputs)
31
what do water budgets at a national/regional scale show
the amount available for human use
32
what do water budgets at a local scale show us
the available soil water
33
what happens to a water budget in the winter
precipitation exceeds evaporation - soil moisture is recharged until a surplus - water can then supply rivers
34
what happens to a water budget in the summer
evaporation exceeds precipitation - soil water is utilised - by the second half of summer there is a deficit
35
what happens to the water budget in autumn
precipitation increases and evapotranspiration falls allowing soil moisture to be recharged once more
36
what are the main human impacts on the global water cycle
deforestation water abstraction agriculture
37
what happens to the percentage of surface runoff when human settlements are created
goes from less than 1% to 20-30% - increase
38
what happens to the percentage of evapotranspiration when human settlements are created
goes from 40-50% to 20-30% - decrease
39
what happens to the percentage of interflow when human settlements are created
goes from 20-30% to 0-30% - decrease
40
what happens to the percentage of groundwater when human settlements are created
goes from 10-40% to 10-20% - decrease
41
Where is the river kennet
in southern England in Wiltshire and Berkshire
42
how large is the river kennet catchment
1200 km**2
43
what material is the upper catchment of the river kennet
chalk which is highly permeable so groundwater is the largest flow
44
when the water from the river kennet is filtered through chalk what happens to it
it will have high oxygen levels and is fast flowing with exceptional clarity
45
what are the native fauna in the river kennet catchment
white clawed crayfish, otters, water voles
46
what is the largest Urban area relying on a water supply from the river kennet
Swindon with a population of 220,000
47
what does the river kennet supply water for
local industries: agriculture, public use
48
which river abstracts water from the upper catchment with boreholes
The river Thames - none of the water is returned
49
what are the impacts of water extraction on the river kennet
1. rates of extraction exceed rates of recharge reducing flows by 10-14% 2. during the 2003 drought flows fell by 20% in the 1990 with dry conditions they fell by 40% 3. lower flows have reduced flooding 4. springs have dried up and reduced saturated overland flow
50
Where is California located
California is a state on the far west of North America
51
what foes California have that is used in periods of drought
has crucial water reserves used in droughts
52
since which year has California been regulating surface water
since 1914
53
when did California start regulating groundwater
2014 (100 years after the regulation of surface water)
54
what percentage of the population rely on groundwater supplies in California
85% of the population and $50 billion of the agriculture industry
55
how many people rely solely on groundwater
6 million
56
how much of the water supply do groundwater stores usually supply in California
30-40% however in drought this has almost doubled
57
Which valley is using pumps and causing the groundwater stores to drain
Central Valley where they are are withdrawing twice as much as nature is replenishing.
58
what does groundwater extraction cause
ground subsidence
59
what is ground subsidence
when water is removed from the groundwater basin clay layers are drained causing clay layers to compact which cause compaction in aquifers.
60
what does the compaction in ground subsidence cause
compaction leads to fewer pore spaces so recharging is harder
61
what act was adopted in California 2014
Sustainable Groundwater management act (SGMA) - groundwater is managed sustainably - if plans are inadequate the state authority can step in
62
what are the solutions to more water being taken out than can be replenished
control groundwater withdrawals deposit water into water storage either naturally or artificially: - naturally by recharge - artificially by creating a recharging pond so water will infiltrate

Geography - A LEVEL (30 decks)

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