Water Cycle and Water Insecurity

Question 1

Systems approach

Answer 1

Studies hydrological phenomena by looking at the balance of inputs and outputs and how water is moved between stores by flows

Question 2

Stores

Answer 2

Reservoirs where water is held, such as the oceans.

Question 3

Fluxes

Answer 3

The rate of flow between the stores.

Question 4

Processes

Answer 4

The physical mechanisms that drive the fluxes of water between the stores.

Question 5

Cryosphere

Answer 5

Areas of the Earth where water is frozen into snow or ice.

Question 6

Blue water

Answer 6

Water is stored in rivers, streams, lakes and groundwater in liquid form (the visible part of the hydrological cycle).

Question 7

Green water

Answer 7

Water stores in the soil and vegetation (the invisible part of the hydrological cycle).

Question 8

Precipitation

Answer 8

The movement of water in any form from the atmosphere to the ground.

Question 9

Evaporation

Answer 9

The change in state of water from a liquid to a gas.

Question 10

Residence time

Answer 10

The average times a water molecule will spend in a reservoir or store.

Question 11

Fossil water

Answer 11

Ancient, deep groundwater from former pluvial (wetter) periods.

Question 12

Transpiration

Answer 12

The diffusion of water from vegetation into the atmosphere, involving a change from a gas to a liquid.

Question 13

Groundwater flow

Answer 13

The slow transfer of percolated water underground through pervious or porous rock.

Question 14

Drainage basin/Catchment

Answer 14

The area of land drained by a river and its tributaries.

Question 15

Watershed

Answer 15

The highland which divides and separates waters flowing to different rivers.

Question 16

Condensation

Answer 16

The change from a gas to a liquid, such as when water vapour changes into water droplets.

Question 17

Dew point

Answer 17

The temperature at which dew forms; it is a measure of atmospheric moisture.

Question 18

Conventional rainfall

Answer 18

Often associated with intense thunderstorms, which occur widely in areas with ground heating such as the tropics and continental interiors.

Question 19

Cyclonic rainfall

Answer 19

A period of sustained, moderately intensive rain; it is associated with the passage of depressions.

Question 20

Orographic rain

Answer 20

Concentrated on the windward slopes and summits of mountains.

Question 21

Interception loss

Answer 21

This water that is retained by plant surfaces and later evaporated or absorbed by the vegetation and transpired.

Question 22

Throughfall

Answer 22

This is when the rainfall persists or is relatively intense, and the water drops from the leaves, twigs, needles, etc.

Question 23

Stem flow

Answer 23

This is when water trickles along twigs and branches and then down the trunk.

Question 24

Infiltration

Answer 24

The movement of water from the ground surface into the soil.

Question 25

Infiltration capacity

Answer 25

The maximum rate at which rain can be absorbed by a soil.

Question 26

Surface run-off

Answer 26

The movement of water that is unconfined by a channel across the surface of the ground. (Overland flow)

Question 27

Throughflow

Answer 27

The lateral transfer of water down slope through the soil via natural pipes and percolines.

Question 28

Percolines

Answer 28

Lines of concentrated water flow between soil horizons to the river channel.

Question 29

Percolation

Answer 29

The transfer of water from the surface or from the soil into the bedrock beneath.

Question 30

Saturated overland flow

Answer 30

The upward movement of the water table into the evaporation zone.

Question 31

Albedo

Answer 31

A measure of the proportion of the incoming solar radiation that is reflected by the surface back into the atmosphere and space.

Question 32

Evapotranspiration (EVT)

Answer 32

The combined effect of evaporation and transpiration.

Question 33

Channel flow

Answer 33

The flow of water in streams or rivers.

Question 34

Channel storage

Answer 34

The storage of water in streams or rivers.

Question 35

Potential evapotranspiration (PEVT)

Answer 35

The water loss that would occur if there was an unlimited supply of water in the soil for use by vegetation.

Question 36

Deforestation

Answer 36

The cutting down and removal of all or most of the trees in a forested area.

Question 37

Afforestation

Answer 37

The planting of trees in an area that has not been forecasted in recent times.

Question 38

River regime

Answer 38

The annual variation in discharge or flow of a river at a particular point of gauging station, usually measured in cumecs.

Question 39

Rising limb

Answer 39

The part of a storm hydrograph in which the discharge starts to rise.

Question 40

Peak discharge

Answer 40

The time when the river reaches its highest flow.

Question 41

Lag time

Answer 41

The time interval between peak rainfall and peak discharge.

Question 42

Falling or recessional limb

Answer 42

The part of a storm hydrograph in which the discharge starts to decrease.

Question 43

Base flow

Answer 43

The normal, day-to-day discharge of the river.

Question 44

Arid region

Answer 44

Characterised by a severe lack of available water

Question 45

Semi-arid region

Answer 45

region that receives precipitation below potential evapotranspiration

Question 46

Discharge

Answer 46

volumetric flow rate of water that is transported through a given cross-sectional area