W - 1.5 -> 1.7

Question 1

Confined aquifer:

Answer 1

• The water is in porous rock
• It’s surrounded by impermeable rock
• Water can’t flow away, but can’t be replenished either

Question 2

Unconfined aquifer:

Answer 2

• The water is in porous rock
• It’s surrounded by permeable rock
• Water can percolate in, and flow away

Question 3

Rocky Mountains:

Answer 3

• Colorado river basin flows to the west, into Mexico
• The great plain is to the east, including the Ogallala Aquifer

Question 4

inputs

Answer 4

• Mainly rainfall (air temperature cools, air is saturated, condensation occurs around nuclei, clouds form)
• Location of rainfall is determined by the rain shadow features (e.g. mountains), or proximity to the ocean (e.g. cold ocean current and Pacific frontal air masses)

Question 5

Climate:

Answer 5

• Amount and timing of rainfall
• Temperature – determines evapotranspiration out
• Freezing conditions – flow is suspended

Question 6

geology:

Answer 6

• Porosity / perviousness of rocks – aquifer storage, so water is released steadily
• Impermeability: quick response to rainfall as water flows quickly through after heavy rain

Question 7

soils

Answer 7

• Deep soils store water – slow release means a steadier river regime
• Permafrost can inhibit percolation and melting can increase water supply

Question 8

complexity:

Answer 8

• large basins have complex regimes and cross climate zones, e.g. Blue Nile / White Nile
• Mountains make for more complexity – e.g. in hot environments, glaciated mountains store water (e.g. Andes)

Question 9

river regimes

Answer 9

• river regimes are defined as the annual variation in the discharge (flow) of a river at a particular point.
• Global patterns of precipitation and evapo-transpiration have a bearing on these fluxes of ‘overland channel flow’ (i.e. rivers).
• The global water budget means that rivers can have distinct annual flow rates (regimes) depending on latitude and topography.
• Whilst seasonal climate is usually the most important factor; geology, soil, vegetation cover and human activities also play a key role.

Question 10

The global pattern of water budgets varies with

Answer 10

latitude - compare tropical temperate and polar

Question 11

yukon:

Answer 11

• Generally has a small change in water budget owing to limited evaporation and precipitation
• River regime is dependent on glacial melt from Llewellyn Glacier in spring
• permafrost covers large area – means largely impermeable
• Spring Thaw – saturated overland flow contributes to rapid rise in river levels (steep spike, which gently declines – still limited evapotranspiration compared to Nile)

Question 12

amazon:

Answer 12

• river regime varies between Equatorial with no dry season and heavy convectional rainfall all year.
• Laterite clays and granites mean larger channel flows over whole basin.

Question 13

nile:

Answer 13

• Drainage basin is tropical with a distinct drier season
• No rainfall at all in northern margins (Sahara) means negative water balance.
• Ethiopian Highlands (largely impermeable geology) = large amounts of runoff transferred downstream
• Rapid fall owing to large evapo-transpiration rates

Question 14

Global Hydrological System

Answer 14

• Closed system on a global scale, but regional drainage basins are open to transfers in and out.
• Freshwater accounts for only 2.5% of total amount, of which only a 1/3 is available for human use and is unevenly distributed – this leads to conflict over this “finite resource”.

Question 15

Stores, Fluxes & Processes

Answer 15

• Size and residence times depends on a number of factors which vary spatially and over time.
• Factors include: soil, geology, climate (latitude & altitude), topography, vegetation, and human land use.
• Consider whether they are predominantly an input to a local system (e.g. precipitation) or an output (e.g. evapo-transpiration, channel flow).

Question 16

Water Budgets

Answer 16

• The annual balance between inputs and outputs within a system (also can show monthly variations)
• Can vary with latitude (e.g. highly positive around ITCZ, negative at tropic lines)

Question 17

conditions likely to produce flashy hydrographic part 1

Answer 17

• small, circular, steep drainage basin
• clay and thin soils
• impermeable rock type
• high drainage density
• thin grass

Question 18

conditions likely to produce flashy hydrographic part 2

Answer 18

• urban land use
• high precipitation intensity
• prolonged precipitation
• fast snowmelt
• evapotranspiration low

Question 19

Impacts on Pakistan from 2022 floods

Answer 19

• 1/3 submerged, 65% sustained by agriculture
• 1000 deaths and 10-bil damage, food shortages

Question 20

Extreme monsoon rainfall

Answer 20

• Monsoon breaks/ dissipates tropical heat, away from equator
• sea breeze that draws wetter maritime Asia from Indian Ocean rises cools and falls as rain
• 5.3% extra rain during monsoon
• Hotter summers mean more unpredictable monsoons as atmosphere can bear more moisture
• every 1 degree GW = 5% more erratic monsoon

Question 21

Heavy and prolonged rainfall:

Answer 21

• jet stream meanders more so rain events do not quickly move on
• Sindh province is relatively arid, so received 336% more rain in July
• Ground and steep slopes saturated quick
• Indus River channel filled to capacity and then burst their banks

Question 22

Intense storms and flash flooding

Answer 22

• steep slopes increase speed of water flow
• ENSO - La Niña - enhances rain
• Flash floods wash away embankments - flood water spreads further, more quickly, dams are destroyed further increasing river flow

Question 23

And snowmelt

Answer 23

• temp rises of 0.42/decade from 1980-2018
• Black pollution particles darken the glacier surface - reduced albedo
• The flow in the Indus River has increased by 3.9 gt per decade

Question 24

CC impact on stores

Answer 24

more droughts and floods, increased runoff and reduced infiltration. Groundwater flow uncertain because human abstraction

Question 25

CC impact on flows

Answer 25

reservoir, lake and wetland storage is decreasing as temp rise. - Little change in soil moisture, precipitation and evaporation cancel each other out. - Degradation of permafrost. - Spring melt of snow starting earlier and decreasing temporary store of snow.

Question 26

Factors leading to reduced water supply and higher uncertainty

Answer 26

- increases in annual temps = higher surface water evaporation - Greater rates of evapotranspiration - desiccation of forest stores - More frequent cyclone and monsoon events - Intensity and frequency of brought rises. - Depleted aquifers leads to problems with groundwater