Water Insecurity - EQ1

Question 1

What percentage of the earth’s water is freshwater?

Answer 1

2.5%

Question 2

A closed system

Answer 2

Occurs when there is transfer of energy but not matter between the system and its surroundings (the inputs come from within the system)

Question 3

An open system

Answer 3

Receives inputs from and transfers outputs of energy and matter to other systems

Question 4

The water stores

Answer 4

Oceans, ice caps and glaciers (cryosphere), groundwater, rivers and lakes (surface water), soil moisture, atmospheric moisture, biological water (biosphere)

Question 5

The global water budget

Answer 5

The annual balance of water fluxes (flows) and the size of the water stores

Question 6

Fossil water

Answer 6

Water that has been contained in an undisturbed space, usually groundwater in an aquifer, for millennia or longer.

Question 7

Inputs into the drainage basin

Answer 7

Precipitation

Question 8

Stores in the drainage basin

Answer 8

Interception storage, surface storage, soil moisture storage, groundwater storage, channel storage

Question 9

Flows (processes) in the drainage basin

Answer 9

Through fall, stem flow, surface runoff (overland flow), infiltration, throughflow, percolation, groundwater flow,

Question 10

Outputs in the drainage basin

Answer 10

Evapotranspiration, channel flow

Question 11

How does vegetation cover affect the rate of infiltration?

Answer 11

Roots help to break up the soil, increasing the infiltration rate

Question 12

How does precipitation intensity affect the rate of infiltration?

Answer 12

Infiltration-excess overland flow will occur when rainfall intensity exceeds infiltration capacity, meaning that the water flows over the surface and infiltration is reduced

Question 13

How does soil and rock type affect the rate of infiltration?

Answer 13

Infiltration rates will decrease as porosity and permeability increase

Question 14

How does water table depth affect the rate of infiltration

Answer 14

As the water table rises during prolonged rainfall the soil will become saturated, reducing infiltration

Question 15

How does slope gradient affect infiltration rates

Answer 15

As gradient increases more water will flow over the surface, reducing infiltration

Question 16

How does temperature affect the rate of evapotranspiration

Answer 16

The rate of eases with temperature. The main energy source is solar radiation, so evaporation and temperature will increase with sunshine hours

Question 17

How does wind affect the rate of evapotranspiration

Answer 17

Wind will increase the rate of evaporation by reducing the relative humidity and preventing saturation of the air

Question 18

How does vegetation cover affect the rate of evapotranspiration

Answer 18

Transpiration will increase with increased vegetation cover, which will depend on the type of vegetation and the season. Vegetation with a low albedo (reflectivity) such as dark forests will increase more solar radiation, increasing evaporation

Question 19

How does soil moisture content affect the rate of evapotranspiration

Answer 19

Will determine the amount of water available for transpiration. It is dependent on soil and rock permeability

Question 20

Human disruptions to the drainage basin hydrological cycle: cloud seeding

Answer 20

The attempt to change the amount or type of precipitation by dispersing substances into the air

Question 21

Human disruptions to the drainage basin hydrological cycle: urbanisation

Answer 21

Urbanisation creates impermeable surfaces that reduce infiltration and increase surface runoff and throughflow through artificial drains; stream and river discharges often increase rapidly as a result

Question 22

Human disruptions to the drainage basin hydrological cycle: dam construction

Answer 22

Damns increase surface water stores and evaporation and reduce downstream river discharge

Question 23

Human disruptions to the drainage basin hydrological cycle: groundwater abstraction

Answer 23

In some locations, groundwater is abstracted from aquifers faster than it is replaced, causing reduced groundwater flow and a lower water table. In other locations, reduced industrial activity or deforestation has increased groundwater storage, increasing the risk of groundwater flooding if the water table reaches the land surface

Question 24

Precipitation (P)

Answer 24

= channel discharge (Q) + evapotranspiration (E) + change in storage (S)

Question 25

Soil moisture surplus

Answer 25

Precipitation is greater than potential evapotranspiration and the soil water store is full, so there is a surplus of soil moisture for plant use, runoff into streams and recharging groundwater supplies. The soil is said to be at field capacity.

Question 26

Soil moisture utilisation

Answer 26

Potential evapotranspiration increases and exceeds precipitation, so there is more water evaporating from the ground surface and being transpired by plants than is falling as rain. Water is also drawn up from the soil by capillary action. The water is gradually used up.

Question 27

Maximum annual temperatures

Answer 27

High temperatures cause maximum evapotranspiration, precipitation is at a minimum and therefore plants use up the soil moisture store. River levels will fall and crops will need irrigation.

Question 28

Soil moisture deficiency

Answer 28

The soil water store has been used up by high rate of evapotranspiration and low precipitation. Plants can only survive if they are adapted to periods of drought or are irrigated

Question 29

River regime

Answer 29

Described the annual variation in the discharge of a river

Question 30

Storm hydrograph

Answer 30

Shows variations in a river’s discharge at a specific point over a short period of time

Question 31

Norma (base) flow

Answer 31

The contribution to river flow from long-term storage sources such as permeable rocks, areas or bog and marsh and peat covered moorlands

Question 32

Rising limb

Answer 32

The increase in discharge in response to surface runoff and throughflow from a rainfall event, unit, peak flow is reached. When the storm begins, the river’s initial response is negligible as the precipitation takes time to reach the channel.

Question 33

Falling limb

Answer 33

The decline in discharge that occurs after peak flow, this segment is usually less steep than the rising limb because throughflow is being released relatively slow into the channel.

Question 34

Lag time

Answer 34

The difference in hours and minutes between the time of maximum precipitation and the time of peak discharge. The lag time varies according to drainage basin conditions. Rivers with a short lag time tend to experience a higher peak discharge and they are more prone to flooding than rivers with a long lag time.

Question 35

Storm runoff

Answer 35

The part of the river flow derived from the immediate rainfall event. The most rapid transfer of water occurs overland and via throughflow.

Question 36

Approach segment

Answer 36

Shows the discharge of the river before the storm (the antecedent flow rate)