Soil moisture and river regime Flashcards Preview

Geography-- Water and Carbon Cycle > Soil moisture and river regime > Flashcards

Flashcards in Soil moisture and river regime Deck (17)
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1
Q

soil moisture budget is…

A

the change in the amount of water stored in the soil throughout the year

2
Q

soil moisture budget is closely linked to..

A

water balance

3
Q

main factors involved in the soil moisture budget

A

precipitation and potential evapotranspiration

4
Q

what is potential evapotranspiration and how does it link to temperature

A

is the amount of evapotranspiration that could occur if there was sufficient water available in the system.
linked to temperature: higher temperature, the greater amount of water available

5
Q

why are there higher levels of evapotranspiration in the summer

A

as it is warmer the air can hold more water (has a higher dew point). and there are more plants= more transpiration

6
Q

what is water surplus

A

where precipitation exceeds evapotranspiration- lots of surface run off

7
Q

what is river discharge

A

is how much water is in the river at any given time

8
Q

how to calculate river discharge

A

cross sectional area of water (metres squared) x speed (m/s) = cumecs (metres cubed/ second)

9
Q

what affects the level of river discharge

A

the speed and velocity of water

  • if there is a higher volume of water then the discharge will be larger
  • if it is faster there will be more discharge per second
10
Q

physical factors that affect storm hydrographs (6)

A

high drainage density= flashy hydrographs
if the basin is already saturated (lag time reduced)
impermeable ground
thick vegetation (subdues hydrograph)
amount and intensity of precipitation
size of drainage basin

11
Q

human factors that affect storm hydrographs (6)

A

deforestation (reduces interception- flashy hydrograph)
afforestation
agriculture
urban areas impermeable surfaces
soft engineering flood management strategies (subdued hydrograph)
water abstraction - reduces base flow

12
Q

(factors that influence the water cycle- deforestation, agricultural soil drainage, water abstraction). example of deforestation

A

tropical south America rainforests

13
Q

explain the impact that deforestation has on the water cycle

A

deforestation can cause decreased rainfall via atmospheric feedbacks
if this decrease in rainfall doesn’t occur then discharge will be significantly increased

14
Q

what happens during agricultural soil drainage

A

subsurface drainage removes excess water from the soil profile

15
Q

how does agricultural soil drainage impact the water cycle

A

artificially increases the speed of throughflow in the soil

can lead to nitrate loss- eutrophication

16
Q

when is water abstracted

A

when demand exceeds amount available

17
Q

how does water abstraction affect the water cycle

A

sinking water tables can make rivers less reliable- as they are maintained in summer by water tables
groundwater also helps sustain surface reservoirs of water that can sustain ecosystems