Soil moisture and river regime Flashcards Preview

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Flashcards in Soil moisture and river regime Deck (17)
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soil moisture budget is...

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


soil moisture budget is closely linked to..

water balance


main factors involved in the soil moisture budget

precipitation and potential evapotranspiration


what is potential evapotranspiration and how does it link to temperature

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


why are there higher levels of evapotranspiration in the summer

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


what is water surplus

where precipitation exceeds evapotranspiration- lots of surface run off


what is river discharge

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


how to calculate river discharge

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


what affects the level of river discharge

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


physical factors that affect storm hydrographs (6)

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


human factors that affect storm hydrographs (6)

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


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

tropical south America rainforests


explain the impact that deforestation has on the water cycle

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


what happens during agricultural soil drainage

subsurface drainage removes excess water from the soil profile


how does agricultural soil drainage impact the water cycle

artificially increases the speed of throughflow in the soil
can lead to nitrate loss- eutrophication


when is water abstracted

when demand exceeds amount available


how does water abstraction affect the water cycle

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