Soil moisture and river regime

Question 1

soil moisture budget is…

Answer 1

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

Question 2

soil moisture budget is closely linked to..

Answer 2

water balance

Question 3

main factors involved in the soil moisture budget

Answer 3

precipitation and potential evapotranspiration

Question 4

what is potential evapotranspiration and how does it link to temperature

Answer 4

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

Question 5

why are there higher levels of evapotranspiration in the summer

Answer 5

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

Question 6

what is water surplus

Answer 6

where precipitation exceeds evapotranspiration- lots of surface run off

Question 7

what is river discharge

Answer 7

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

Question 8

how to calculate river discharge

Answer 8

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

Question 9

what affects the level of river discharge

Answer 9

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

Question 10

physical factors that affect storm hydrographs (6)

Answer 10

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

Question 11

human factors that affect storm hydrographs (6)

Answer 11

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

Question 12

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

Answer 12

tropical south America rainforests

Question 13

explain the impact that deforestation has on the water cycle

Answer 13

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

Question 14

what happens during agricultural soil drainage

Answer 14

subsurface drainage removes excess water from the soil profile

Question 15

how does agricultural soil drainage impact the water cycle

Answer 15

artificially increases the speed of throughflow in the soil

can lead to nitrate loss- eutrophication

Question 16

when is water abstracted

Answer 16

when demand exceeds amount available

Question 17

how does water abstraction affect the water cycle

Answer 17

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