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Year 2 Ecological Systems > 17. River Flows > Flashcards

17. River Flows Flashcards

1
Q

are droughts natural?

A

Yes

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2
Q

What does a river normally show?

A

A flow regime

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3
Q

Where do we often see high flows in the uk?

A

Spring melt and autumn floods

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4
Q

How do river reigimes vary in the Southern Hemisphere?

A

Large peaks in winter floods little flow in the summer

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5
Q

What can droughts be considered as?

A

A disturbance effect

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6
Q

Why might flow be lower in winter?

A

water is frozen

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7
Q

Why do we expect low flows?

A

they occur naturally, expected to happed

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8
Q

Can low flows be due to human activity?

A

Yes, diversion of water, agriculture ect

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9
Q

What is a drought

A

extreme low flow periods

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10
Q

Are fresh water systems resilient to drought effects?

A

Yes they can often bounce back

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11
Q

How long can droughts last?

A

From a few weeks to a few months

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12
Q

Which animals could be effected by dorught

A

fish, different time of year can effect damage to orgaisms

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13
Q

How can the type of river determine flow

A

perennial, temporay, bed fed, consecutive

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14
Q

What can excaserbate drought

A

human impact

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15
Q

Why are droughts more complex than floods

A

can be longer, supra seasonal, more regional effect

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16
Q

What is a press disturbance

A

a single disturbance, with one response

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17
Q

What is ramp disturbance

A

continuing disturbance overtime

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18
Q

Which year did we see a very dry summer followed by a wet winter?

A

1976

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19
Q

What is a supraseasonal drought

A

long periods over time of drought

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20
Q

Which type of river was more effected due to drought,

A

bed fed rivers

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21
Q

how do we decided how low a river flow is in the summer

A

summer low flow, qL, lowest average of severn consequtive summers

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22
Q

How do droughts affect river organisms

A

reduced depth and wetted area, reduction in current veolocity

23
Q

how can reduced veolocity effect organims

A

could effect breathing, now given enough oxygen, less food for fishes

24
Q

If there is low flow, how are sediments effected

A

sediments get stuck in gravels and reduced breeding fish

25
Q

what do droughts commonlly bring

A

increased temperature, variability, changes in development rates

26
Q

Can species richness increase during drought

A

yes, dome detrivoures may be able to find more food, intermediance disturbance theory

27
Q

How can invertebrates adapt during drought conditions

A

breath atmospheric oxygen, adapted gills, can survive damp conditions eg wood/substrate

28
Q

What can invertebrates go into during hot and dry conditions

A

aestivation, hibernation for warmer temperatures

29
Q

Where can invertebrates go during times of low flow

A

hyperheos, or permanent systems, or will just leave the catchment

30
Q

What is the main impact for fish during droughts

A

low oxygen

31
Q

How can we see areas in drought

A

some rivers with drought will have very low fish return in upcoming years

32
Q

how can filamentos algae resond to drought

A

can bloom during drought, negative response to high flows

33
Q

How are diatoms effected by droughts

A

positive response to light

34
Q

Which river saw a huge fish impact in 1976

A

the Welsh Wye

35
Q

What happend with oxygen levels in 1976

A

huge loss of oxygen down to less than 2

36
Q

What are dams built for

A

public water supply, irrigaiton, hydro electric, flood control

37
Q

How many of the worlds rivers are regulated

A

2/3

38
Q

where is most dam building taking place

A

china

39
Q

Of all the rivers capable of making power in africa, how many have been regulated

A

100%

40
Q

What impact in the construction phase are there on a river

A

channing from a riverine to a lacustrine environment

41
Q

how many people where resettled in terms of the lake kariba dam

A

40-80million

42
Q

What do reservoiurs result in

A

reduction in the variability in flow

43
Q

What does the dam trap behind it

A

sediment, less fine material moving downstream, temperature will be more variable

44
Q

If the lake stratisfied and the water is taken from the bottom of the dam what happens

A

water taken from anoxic conditions

45
Q

what life will cling to rocks in low flows

A

mosses

46
Q

How much of the sediment load gets past the aswan dam

A

12%

47
Q

What will settle in a lake system

A

CPOM, coarse particulate organic matter

48
Q

what flow does the snake river have behing it

A

no flow

49
Q

WHat are anadromous fish

A

fish that return to fresh water

50
Q

what is the major dam in china

A

three gorges

51
Q

how many of the worlds largest dams are in china

A

over 50%

52
Q

how many people have river blindness

A

15.5 million

53
Q

what is schistosomaisis

A

snail fever

Year 2 Ecological Systems (23 decks)

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