Interception

Question 1

what is canopy interception and where does the water go

Answer 1

precipitation that is temporarily stored on plant surfaces. water never reaches the soil surface, directly evaporates off leaves

Question 2

what is stemflow

Answer 2

water that reaches ground by flowing down tree trunks and stems

Question 3

what is throughfall

Answer 3

water reaching ground directly through openings in canopy

Question 4

what does interception depend on (2)

Answer 4

nature and density of vegetation

Question 5

how to calculate net rainfall

Answer 5

stemflow add throughflow

Question 6

what impact does interception have on raindrops in terms of chemistry

Answer 6

alters size and chemical composition of drops as it changes the kinetic energy of rain drops

Question 7

spatial variability of net rainfall is __ than gross rainfall

Answer 7

greater

Question 8

where is throughfall concentrated on vegetation

Answer 8

concentrated stemflow near trunks

Question 9

what are the two major hyptheses in relation to interception

Answer 9

1. Interception losses have no effect on catchment water balance
2. Interception losses reduces net inputs, diminishing soil water recharge and streamflow

Question 10

what does interception represent in terms of the catchment hydrological balance

Answer 10

a net loss

Question 11

when does precipitation evaporate at a greater rate

Answer 11

when it is intercepted as opposed to transpired

Question 12

how much more evaporation occurs than transpiration

Answer 12

2-3 times more

Question 13

what is the formula for calculating interception

Answer 13

precipitation above the vegetation layer MINUS throughfall MINUS stemflow
I = P - T - S

Question 14

how to measure throughfall

Answer 14

gauges

Question 15

how to measure stemflow

Answer 15

gutters around plants

Question 16

what does throughfall depend on (5 factors)

Answer 16

Canopy cover
Leaf area index (LAI) – (surface area/crown area)
Evergreen or deciduous
Leaf surface smoothness
Leaf shapes and orientation

Question 17

what are 2 factors that stemflow depends on

Answer 17

branch orientation

roughness of bark

Question 18

when is interception storage capacity greatest

Answer 18

when canopy is dry (at start of rainfall event)

Question 19

what is altered when the leaves become wet and how does this impact the way the rain moves

Answer 19

once leaves are wet, surface tension is overcome and most rainfall is lost as leaf drip or throughfall

Question 20

what vegetation characteristics mean that interception loss will be greater

Answer 20

denser vegetation

taller vegetation

Question 21

what type of ecosystem are intercepetion losses greater at

Answer 21

coniferous forests

Question 22

coniferous forests on peat bogs intercept __% of annual precipitation

Answer 22

25-35% (A LOT) - average is 15-25%

Question 23

how to calculate interception ratio

Answer 23

interception loss / gross precipitation

Question 24

as rainfall increases what happens to the interception ratio

Answer 24

it reduces

Question 25

is interception loss greater from forests or grasslands

Answer 25

forests