variations in run off and water cycle

Question 1

what do hydrograph show?

Answer 1

shows a rivers discharge over a period of time

Question 2

what is river discharge?

Answer 2

the volume of water that flows in a rover per second

Question 3

what is river discharge measured in?

Answer 3

cumecs

cubic metres 3 per second

Question 4

what increases a rivers discharge?

Answer 4

high levels of surface runoff as more water is entering the river increasing its volume

Question 5

what do flood hydrographs show?

Answer 5

river discharge around the time of a storm event

cover s short time period

Question 6

what is peak discharge? SH

Answer 6

the highest point on the graph when discharge is at its greatest

Question 7

what is lag time? SH

Answer 7

the delay between peak discharge and peak rainfall

Question 8

why does lag time occur?

Answer 8

it takes time for rainwater to flow into the river

Question 9

if lag time is shorter what does this mean?

Answer 9

that peak discharge is likely to be higher as to be higher as there is a greater amount of water flowing into the river in a short amount of time

Question 10

what is the rising limb? SH

Answer 10

this is the part of the graph that leads up to peak discharge
if it is steeper it indicates that there is a large amount of water entering in a short time

Question 11

what is the falling limb?

Answer 11

after peak discharge

less water so discharge is decreasing

Question 12

what is baneful discharge?

Answer 12

this is when discharge reaches the point in which water reaches the top of the river

Question 13

what is a flashy hydrograph?

Answer 13

symmetrical falling and rising limb

not much storage and rapid runoff

Question 14

what factors are runoff and hydrography shape affected by?

Answer 14

• size of basin
• shape of basin
• groud steepness
• rock and soil tye

Question 15

how does size of basin affect runoff and hydrography shape?

Answer 15

a larger basin can catch more water meaning peak discharge is likely to be greater
a smaller basin is likely to have a higher lag time as don’t have to travel as far

Question 16

what natural factors are run off, hydrographs and water cycle affected by?

Answer 16

storms and precipitation

seasonal changes and vegetation

Question 17

how does vegetation affect water cycles?

Answer 17

deciduous trees (lose leaves)
more vegetation can reduce peak discharge and runoff as lost through transpiration and uptake

Question 18

what are human activities that affect water cycle?

Answer 18

famring practises
land use change
water abstraction

Question 19

how do framing practices affect water cycle?

Answer 19

it can affect infiltration
ploughing can break up surface so more water can infiltrate reducing runoff
crops increase interception reducing runoff and more evapotranspiration
livestock trample and compact the soil decreasing infiltration
irrigation increase runoff, groundwater can fall if it is extracted for irrigation

Question 20

how does land use change affect water cycle?

Answer 20

deforestation - not intercepted, increase infiltration, if plants removed then the dead material cannot hold water which usually reduces infiltration
construction - impermeable layer makes flooding more likely

Question 21

how does water abstraction affect water cycle?

Answer 21

if more water is abstracted it reduces the amount of water in lakes, resoivois and groundwater
it can lower the water table meaning that stores can become depleted
groundwater will not be able to recharge rivers and water table