Topic 5 - EQ1 - Water (Miss M)

Question 1

What is the order of the biggest water stores on earth?

Answer 1

Oceans then cryosphere then terrestrial then atmosphere

Question 2

What are fluxes?

Answer 2

Measurements of the rate of flow between stores

Question 3

What are processes?

Answer 3

The physical mechanisms such as evaporation that drive the flow of water between the stores

Question 4

What is blue water?

Answer 4

Water stored in rivers, lakes, oceans, streams and groundwater (visible)

Question 5

What is green water?

Answer 5

Water stored in the soil and vegetation (invisible)

Question 6

In which store does water have the longest residence time in?

Answer 6

Cryosphere, followed by groundwater then oceans then other terrestrial stores (other than groundwater), finally the shortest RT is in the atmosphere (just 10 days)

Question 7

What are the two types of energy that the Water cycle relies on? Why?

Answer 7

• Solar energy is required to evaporate the water
• Gravitational potential energy keeps the water moving around the atmosphere and around the system through inputs, outputs and flows

Question 8

What is the global water budget?

Answer 8

The global annual balance of water flows and size of water stores

Question 9

Is the water system considered a closed system?

Answer 9

Yes - because of this NASA estimates that every drop of freshwater has been consumed at least once before

Question 10

What is evapotranspiration?

Answer 10

Evapotranspiration is the sum of evaporation from the land surface plus transpiration from plants

Question 11

What percentage of the Earth’s water is freshwater?

Answer 11

2.5%

Question 12

Where is the majority of freshwater stored?

Answer 12

Glaciers and ice caps, and ground water (glacial water is inaccessible)

Question 13

What is the main source of water for humanity?

Answer 13

Rivers - the water in rivers is just 0.007% of total water on earth

Question 14

Other than accessibility of usable water, what is the main other issue affecting the global usable water supply?

Answer 14

A rising population. The water cycle is closed and so the amount of water in the system stays stagnant, as the population increases the amount of water stays the same and with future overpopulation will come limited water availability.

Question 15

What is the input into the drainage basin?

Answer 15

Precipitation

Question 16

What are the 5 stores of water in the drainage basin?

Answer 16

Interception, surface storage, soil water storage, groundwater storage and Channel store

Question 17

What are the 6 transfers of the drainage basin system?

Answer 17

Through flow (stem flow), infiltration, percolation, surface run-off, soil water through-flow, groundwater through-flow

Question 18

What are the 3 outputs of the drainage basin system?

Answer 18

Evaporation, transpiration, river discharge

Question 19

What is Convectional rainfall?

Answer 19

It is when the land becomes hot the air above expands and rises as it becomes warmer too, as the air rises it cools and its ability to hold water vapour decreases so condensation occurs and clouds develop. If the air continues to rise then rain will fall.

Question 20

What is cyclonic rainfall (frontal rainfall)

Answer 20

When warm air (lighter and less dense) is forced to rise over cold, denser air causing water vapour to condense and form rain, because as warm air rises it cannot hold as much water vapour and so condensation occurs, clouds form and it rains

Question 21

What is Orographic (relief) rainfall?

Answer 21

When air is forced to rise over a barrier, such as a mountain, it cools and condensation occurs causing rainfall concentrated on the windward slopes of the mountains or hills. Heavier rain on higher lands means that the downward slope is in a rain shadow and receives minimal rainfall.

Question 22

Where is Convectional rainfall most common?

Answer 22

Tropical areas however it is sometimes seen in the South of the UK in summer

Question 23

What rainfall do we see most in the UK?

Answer 23

Cyclonic rainfall

Question 24

What type of system is the Drainage Basin system?

Answer 24

The drainage basin is a subsystem within the global hydrological cycle. It is an open system as it has external inputs and outputs that causes the amount of water in the basin to vary over time. There are various inter-linkages between components of the system.

Question 25

How does interception cause variation within the drainage basin?

Answer 25

It delays the precipitation reaching the surface then reaching the river channel, increased lag time effectively

Question 26

What type of vegetation cover increases interception?

Answer 26

Denser types of vegetation, like coniferous forests

Question 27

What ‘type of precipitation’ is interception at its highest at?

Answer 27

Light rainfall of short periods (dry leaves and stems have the greatest water storage capacity)

Question 28

What is the main cause of secondary interception?

Answer 28

Coverage of shrubs and ground vegetation which catches rainfall from higher up trees/vegetation stopping water being drained.

Question 29

What diminishes interception greatly?

Answer 29

• Deforesting land greatly diminishes interception in the drainage basin, unlike before there is nothing to stand in the way of precipitation and the surface.
• The season of the year for deciduous trees, there is considerable less interception in areas with deciduous trees during autumn and winter as the trees have no leaves to catch precipitation

Question 30

What are the main things affecting the rate of infiltration?

Answer 30

Amount of water already in the soil (degree of saturation + water table level), vegetation cover, gradient of land and permeability of soil

Question 31

What is saturated overland flow?

Answer 31

Saturated overland flow happens when water accumulates in the soil until the water table reaches or ponds on the surface.

Question 32

What are the characteristics of the areas where saturated surface flow happens?

Answer 32

This particularly happens in areas of land with thin soils of moderate permeability

Question 33

What is infiltration excess surface flow

Answer 33

Infiltration-excess overland flow occurs when the rainfall intensity exceeds the infiltration capacity, so the excess water flows over the surface

Question 34

What helps increase the rate of soil throughflow?

Answer 34

• A downwards gradient towards the river

- Low water table and little saturation so throughflow is not restricted

Question 35

What helps increase the rate of percolation?

Answer 35

• No/little gradient so throughflow is not promoted as opposed to percolation
• Permeable (porous and pervious) rocks

Question 36

What helps increase the rate of groundwater flow?

Answer 36

• Rate of groundwater flow will also increase according to the angle of rock strata as gradient will increase speed of flow
• Permeability of rocks (pervious and porous) to allow water to move through rocks

Question 37

What increases evaporation from the drainage basin?

Answer 37

• Higher temperatures
• Wind (Wind moving over a water or land surface can also carry away water vapor, essentially drying the air, which leads to increased evaporation rates)

Question 38

What increases transpiration in the drainage basin?

Answer 38

• Wind (Wind will move the air around, with the result that the more saturated air close to the leaf is replaced by drier air)
• More vegetation
• More leaves (especially dark leaves
• Soil moisture content (determines water available for transpiration)
• More light intensity (stomata opens + more photosynthesis occurs)

Question 39

How can humans disrupt the Drainage basin?

Answer 39

• Cloud seeding (dispersion of substances into the air to change the amount of precipitation, usually increase precipitation)
• Deforestation (much less interception)
• Using groundwater from aquifers quicker than water is replaced (greatly reduces groundwater flow and can cause rivers to run dry)
• Urbanisation disrupts the interception store and infiltration transfer of the drainage basin because urbanisation creates impermeable surfaces that reduces infiltration and increases surface runoff and through-flow through man-made drains, this means the river discharge often increases rapidly and unnaturally
• Dams and reservoirs disrupt the outputs of the drainage basin because the dam increases surface water stores which increases evaporation, this then reduces downstream river discharge

Question 40

What does a water budget reflect?

Answer 40

Water budget reflects the natural annual balance between inputs and outputs in a given river area which are influenced by climate. The balance determines the amount of moisture in soils.

Question 41

What is the formula for water budget?

Answer 41

The formula used is: Precipitation = channel discharge (water flow out of basin) + evapotranspiration +/- change in water storage. Whatever falls as precipitation should be balanced by the other components.

Question 42

What is field capacity?

Answer 42

Normal amount of water that can be held in the soil

Question 43

What is potential vs actual evapotranspiration.

Answer 43

The amount of water that could be lost by evapotranspiration if there was sufficient moisture available vs the amount of water that is actually lost through evapotranspiration

Question 44

What is soil moisture surplus?

Answer 44

When the soil moisture is full and there is excess water available for plants, runoff and recharge (Prec > Evapotranspiration)

Question 45

What is soil moisture utilisation?

Answer 45

Occurs when moisture from the soil stores is being used by vegetation/humans building a deficit as the precipitation rate is less than Evapotranspiration (Evapotranspiration > Prec)

Question 46

What is soil moisture recharge?

Answer 46

Occurs when moisture from precipitation infiltrates and percolates in the stores to relay the soil moisture utilisation deficit (Prec > Evapotranspiration)

Question 47

What is soil moisture deficit?

Answer 47

When there is not enough water left in the soil to match potential Evapotranspiration. Rivers run dry and drought ensues.

Question 48

What are the 6 main factors affecting a river regime?

Answer 48

Humans, precipitation, vegetation, temperature, size of the river and geology/soil

Question 49

How do humans affect river regime?

Answer 49

Man made dams regulate the flow of water which changes the discharge at times different to what would happen naturally

Question 50

How does precipitation affect river regimes?

Answer 50

Regimes often reflect rainfall seasons or when snow, or glaciers, melt in the spring-summer time

Question 51

How does temperature affect river regimes?

Answer 51

Warmer summer temperatures mean more evaporation which will be marked in the regimes

Question 52

How does the size of the river affect the river regime?

Answer 52

Larger rivers have more complex regimes because of varied catchments

Question 53

How does geology and soil affect river regimes?

Answer 53

Water is stored as groundwater in permeable rocks and is gradually released into the river as base flow, this tends to regulate the flow during dry periods

Question 54

What is a storm hydrograph?

Answer 54

A storm hydrograph is a graph showing variation in discharge (volume) of water in response to a rainfall event.

Shows response over a short period of time. Normally after an individual storm (few days).

Question 55

What are the factors that increase the probability of flooding?

Answer 55

• Thin soil (low permeability and saturated quickly)
• Steep relief (promotes surface run off not infiltration)
• Human settlements with the laying of concrete and other impermeable surfaces
• Impermeable rock layers (no percolation)
• High intensity and prolonged rainfall
• Deforestation (reduced infiltration and interception leading to possible saturated excess overland flow)

Question 56

Does urbanisation increase or decrease evapotranspiration? Why?

Answer 56

Decreases evapotranspiration, water runs off on the surface instead (see GoodNotes graphic pg31)