EQ1

Question 1

where does the power that drives the global hydrological cycle come from

Answer 1

solar energy - in the form of heat

gravitational energy - causes rivers to flow downhill and precipitation to fall to the ground

Question 2

stores

Answer 2

reservoirs where waters held 
there are 4 main stores 
- oceans
- glaciers and ice sheets (the cryosphere)
- surface run-off
- the atmosphere

Question 3

flows

Answer 3

transfers of water from one to another 
there are 4 main flows: 
- precipitation
- evaporation
- transpiration
- vapour transport

Question 4

fluxes

Answer 4

the rates of flow between stores

the greatest fluxes occur over the oceans

Question 5

the global water budget

Answer 5

takes into account all the water held in the stores and flows of the global hydrological cycle
only 2.5% of it is freshwater; the rest is in the oceans

Question 6

the drainage basin

Answer 6

is a subsystem within the global hydrological cycle
its an open system with inputs and outputs
main input is precipitation

Question 7

interception (flow)

Answer 7

the retention of water by plants and soils which is subsequently evaporated or absorbed by the vegetation

Question 8

infiltration (flow)

Answer 8

the process by which water soaks into, or is absorbed by the soil

Question 9

percolation (flow)

Answer 9

similar to infiltration, but a deeper transfer of water into permeable rocks

Question 10

throughflow (flow)

Answer 10

the lateral transfer of water downslope through the soil

Question 11

groundwater (flow)

Answer 11

the very slow transfer of percolated water through pervious or porous rocks
also known as base flow

Question 12

surface run-off (flow)

Answer 12

the movement of water that is unconfined by a channel across the surface of the ground
also known as overland flow

Question 13

river or channel flow (flow)

Answer 13

takes over as soon as the water enters a river or stream; the flow is confined within a channel

Question 14

evaporation (output)

Answer 14

the process by which moisture is lost directly into the atmosphere from water surfaces , soil and rock

Question 15

transpiration (output)

Answer 15

the biological process by which water is lost from plants through minute pores and transferred to the atmosphere

Question 16

discharge/ channel flow (output)

Answer 16

into another, larger drainage basin, a lake or the sea

Question 17

physical factors affecting the drainage basin

Answer 17

climate
soils
geology
relief
vegetation

Question 18

how does climate affect drainage basin systems

Answer 18

climate has a role in influencing the type and amount of precipitation overall and the amount of evaporation, i.e. the major inputs and outputs
climate also has an impact on the vegetation type

Question 19

how do soils affect drainage basin systems

Answer 19

soils determine the amount of infiltration and throughflow and , indirectly geology affects soil formation

Question 20

how does geology affect drainage basin systems

Answer 20

geology can impact on subsurface processes such as percolation and groundwater flow [and therefore, on aquifers]
indirectly, geology affects soil formation

Question 21

how does relief affect drainage basin systems

Answer 21

relief can impact on the amount of precipitation

slopes can affect the amount of runoff

Question 22

how does vegetation affect drainage basin systems

Answer 22

the presence or absence of vegetation has a major impact on the amount of interception, infiltration and occurrence of overland flow, as well as on transpiration rates

Question 23

impacts of human activity on drainage basin systems

Answer 23

river management
deforestation
changing land use - agriculture
changing land use - urbanisation

Question 24

river management

Answer 24

construction of storage reservoirs holds back river flows
abstraction of water for domestic and industrial use reduces river flows
abstraction of groundwater for irrigation lowers water tables

Question 25

deforestation

Answer 25

clearance of trees reduces evapotranspiration, but increases infiltration and surface runoff

Question 26

changing land use - agriculture

Answer 26

arable to pastoral: compaction of soil by livestock increases overland flow
pastoral to arable: ploughing increases infiltration by loosening and aerating the soil

Question 27

changing land use - urbanisation

Answer 27

urban surfaces [tarmac, tiles, concrete] speed surface runoff by reducing percolation and infiltration
drains deliver rainfall more quickly to streams and rivers, increasing chances of flooding

Question 28

components of drainage basin most affected by humans

Answer 28

• evaporation and evapotranspiration
• interception
• infiltration
• groundwater
• surface run-off

Question 29

Amazonia case study

Answer 29

contains the worlds largest area of tropical rainforest
deforestation here has disrupted the drainage basin cycle in a number of ways including:
- a lowering of humidities
- less precipitation
- more surface runoff and infiltration
- more evaporation, less transpiration
- more soil erosion and silt being fed into rivers

Question 30

what is a river regime

Answer 30

the annual variation in the discharge or flow of a river at a particular point and is usually measured in cumecs

Question 31

what influences a rivers regime

Answer 31

• the size of the river and where discharge measurements are taken along its course
• the amount, seasonality and intensity of the precipitation
• the temperatures, with possible meltwater and high rates of evaporation in summer
• the geology and soils, particularly their permeability and porosity; groundwater noted in permeable rocks is gradually released into the river as base flow
• the type of vegetation cover: wetlands can hold water and release it slowly into the river
• human activities aimed at regulating a rivers discharge

Question 32

water budget

Answer 32

the annual balance between precipitation, evapotranspiration and runoff
calculated with
P = E + R +/- S

Question 33

storm hydrographs

Answer 33

show discharge changes over a short period of time usually a few days
they put two things:
- the occurrence of a short period of rain over a drainage basin
- the subsequence discharge of the river

Question 34

main features of a storm hydrograph

Answer 34

• once the rainfall starts, the discharge begins to rise; this is known as the rising limb
• peak discharge is reached over some time after the peak rainfall because the water takes time to move over and through the ground to each the river
• the time interval between peak rainfall and peak discharge is known as lag time
• once the input of rainwater into the river starts to decrease, so does the discharge; this is shown by the falling or recessional limb
• eventually the rivers discharge returns to its normal level or base flow