EQ1 5.1 HYDROLOGICAL CYCLE Flashcards
precipitation (input)
moisture in any form
interception (storage)
temporary storage, as water is captured by plants, buildings and hard surfaces before reaching the soil
vegetation storage (storage)
any moisture taken up by vegetation and held within plants
surface storage (storage)
any surface water in lakes, ponds, puddles
soil moisture (storage)
water held within the soil
groundwater storage (storage)
water held within permeable rocks (also known as an aquifer)
channel storage (storage)
water held in rivers and streams
infiltration (flows and processes)
water entering the topsoil. most common during slow or steady rainfall
throughflow (flows and processes)
also known as inter-flow; water seeping laterally through soil below the surface, but above the water table
percolation (flows and processes)
the downward seepage of water through rock under gravity, especially on permeable rocks e.g. sandstone and chalk
stem flow (flows and processes)
water flowing down plant stems or drainpipes
base flow (flows and processes)
also known as groundwater flow. slow moving water that seeps into a river channel
channel flow (flows and processes)
the volume of water flowing within a river channel (also called discharge and run off)
surface runoff (flows and processes)
also called overland flow. flow over the surface during an intense storm, or when the ground is frozen, saturated or on impermeable clay.
evaporation (outputs)
the conversion of water to vapour
transpiration (outputs)
water taken up by plants and transpired onto the leaf surface
evapotranspiration (outputs)
the combined effect of evaporation and transpiration
river discharge (outputs)
the volume of water passing a certain point in the channel over a certain amount of time.
where is most of the worlds freshwater locked up
in the cryosphere
where is less than 0.4% of freshwater is contained
within surface lakes, rivers,atmosphere,biosphere
the balance of this is known as the global water budget
oceans lose more water through evaporation than they gain through precipitation, whereas the opposite is true for landmasses. surface run off makes up the distance- known as the balance
what does the ITCZ stand for
intertropical convergence zone (a wide belt of clouds within the tropics)
importance of the tropics
steep angle of the sun over tropical oceans allows intense solar radiation = high evaporation
trade winds transfer water vapour towards the ITCZ
there convectional currents lift air so that it cools and condenses into clouds causing heavy rainfall
where’s most the worlds rainfall created
ICTZ (the biggest flux transferring water from oceans to land)
what are huge atmospheric flows of moisture called
tropospheric rivers
how much of the earths freshwater is locked up in the cryosphere
2/3
what is the cryosphere
places where the temperature remains below freezing for much of the year, such as ice sheets and glaciers
what is happening because of the warming global climate
the global climate is warming, some of the frozen cryosphere water is released by melting to flow into the sea- adding to the closed hydrological cycle
the importance of the polar regions
the polar regions contribute the the circulation of water and the transfer of heat around the world which drive the global hydrological cycle. an ocean circulation occurs known as the thermohaline circulation - sometimes called the global conveyor belt
how does the thermohaline circulation work
ocean water in the polar regions is colder, more saline(salty) and denser than in tropics so it sinks
the cold sinking water draws in warmer water from the ocean surface which draws water across the surface from the tropics
the movement of water from the tropics draws cold water up from the ocean bottom to be warmed again
what is fossil water
untapped ancient stores of freshwater exist in the polar regions and beneath many deserts
examples of fossil water include
aquifers beneath Greenlands ice sheet and under the Kenyan desert
how many metres of freshwater does Kenyas lotikipi aquifer contain
200billion
what is the global hydrological system
a closed system
what does a closed system mean
the total amount of water in the hydrological system does not change
which two processes drive the hydrological system
solar energy and gravitational potential energy
how does solar energy drive the hydrological system
solar energy causes evaporation which leads to condensation and therefore precipitation
how does gravitational potential energy drive the hydrological system
gravitational potential energy keeps the water moving throughout the system
how much of the earths water is locked up in oceans
96.5%
how much of the earths water is locked up as freshwater
2.5%
in oceans how is the vast majority of water stored
in liquid form - only a minute fraction stored as icebergs
in the cryosphere how is the vast majority of water sstored
a solid state, with some in liquid form as melt water and lakes
on land how is the vast majority of water stored
in rivers, streams,lakes and groundwater in liquid form . can also be stored in vegetation after interception or beneath the surface in the soil
in the atmosphere how is the vast majority of water stored
water exists as vapour with the carrying capacity directly linked to temperature
shifts in the worlds climactic zones mean that some stores are…
depleting e.g. polar ice and mountain glaciers without being replenished
what happens in areas that are warming
ground surfaces dry out as evaporation increases. global air circulation then takes this extra vapour to the cooler areas where it condenses into clouds and precipitation
polar hydrology
freeze/thaw seasonal differences 85% solar radiation reflected permarfrost-impermeable limited vegetation annual precipitation is less than 200mm
tropical rainforest hydrology
few seasonal differences
dense vegetation consumes 75% of precipitation
limited surface infiltration
annual precipitation over 2000mm
what is the water table
the boundary between water-saturated ground and unsaturated ground.
why does an areas water table fluctuate
water seeps downward from the surface and a water table usually isn’t flat or horizontal. water tables often follow the topography of. upward and downward tilts of land above them.
what factors are water tables influenced by
geology, weather, groundcover and landuse
what is an aquifer
rocks containing groundwater that can be extracted
what is a flux
the movement or transfer of water between stores
what are the hydrological cycle stores
atmosphere, groundwater, biosphere,surface water, cryosphere, oceans
what percentage of freshwater is in oceans
0%
what percentage of freshwater is in icecaps
68.7%
what percentage of freshwater is in rivers and lakes
1.2%
hydrological system is made up of 3 systems
stores,fluxes,processes
what happened in the last iceage
more water was held in the cryosphere in a solid form as snow or ice. as less was held in the ocean sea levels dropped over 140m lower than they are today
oceans contain ..% of the worlds total water
96.7
the cryospere contains ..% of the worlds total water
1.9%
which is the smallest water store
the atmosphere
major fluxes are driven by which key processes
precipitation,evaporation, cryospheric exchange and a runoff generation (both surface and groundwater)
what are residence times
average time a watermolecule will spend in that resevoir or store.
what is the residence time for groundwater
groundwater is deepseated and can spend over 10,000 years beneath the earths surface
what is fossil water
ancient groundwater such as that found deep below the sahara desert (the result of former pluvial periods). not renewable or reachable for human use
what has icecore dating suggested about the residence time of some water in the antarctic ice
the residence time is over 800,000 years
water stored in soil (soil moisture) have short residence times of
2-50weeks because its spread very thinly across the earth
soil moisture is is easily lost to other stores because of is accessibility by
evaporation,transpiration, groundwater flow or recharge
what is the residence time for atmospheric water
10days
what is the link between residence times and levels of water pollution
stores with a slower turnover tend to be more easily polluted as the water is in situ for a longer length of time
only ..% of the earths water occurs as freshwater
2.5
around ..% of earths water is locked up in snowflakes, icesheets, icecaps and glaciers
69
..% of the earths freshwater occurs as groundwater
30%
only ..% of freshwater is accessible for human use
1%
what is currently the main source of surface water for humans
rivers
rivers contribute only ..% of total water
0.007%
what is being used widely to extend the availibility of freshwater supplies
desalination
what do we mean when we talk about stores
When we talk about stores we include all water stored as either water vapour, ice, saline or freshwater.
Examples of global stores of water include:
Oceans
Lakes
Aquifers (underground lakes)
The cryosphere (glaciers and ice sheets)
Examples of local stores of water include:
Vegetation storage.
Surface storage.
Soil moisture.
Groundwater storage.
Flows are how water moves from one store to another, examples include:
Infiltration. Throughflow. Percolation. Stem flow. Base flow. Channel flow. Surface runoff.
The following processes drive the flows between the stores:
Precipitation. Evaporation. Transpiration. Cryosphere (glaciers and ice sheets) exchanges. Runoff.
is the hydrological cycle a closed system
There is a fixed amount of water on the Earth. This is called a closed system because water cannot enter or leave the Earth and its atmosphere.
how is water found on earth
as a gas called water vapour, as liquid water, and as solid ice.
what % of earths water is in the oceans and seas
96.5%
what % of earths water is in freshwater
2.5%
what % of earths water is in other saline (salty) water sources
0.9%
what is freshwater
water that isn’t salty
what % of earths freshwater is in the cryosphere (glaciers, ice caps)
68.8%
what % of earths freshwater is groundwater
30%
what % of earths freshwater is surface water
1.2%
what % of Earth’s surface water is in ground ice and permafrost.
69% of Earth’s surface water is in ground ice and permafrost.
of Earth’s surface water is in lakes
20% of Earth’s surface water is in lakes.
what % of Earth’s surface water is in soil moisture
3.8% of Earth’s surface water is in soil moisture.
what % of Earth’s surface water is in the atmosphere.
3.0% of Earth’s surface water is in the atmosphere.
what % of Earth’s surface water is in swamps and marshes.
2.6% of Earth’s surface water is in swamps and marshes.
what % of Earth’s surface water is in rivers.
0.5% of Earth’s surface water is in rivers.
what % of Earth’s surface water is in the biosphere (living things)
0.26% of Earth’s surface water is in the biosphere (living things).
