The Water Cycle Flashcards
what type of system is the hydrological cycle
closed
What is a closed system
system where only energy can be exchanged but not matter
What is the hydrological cycle
circulation of water around the earth
Name the 2 sources that power the global hydrological cycle
Solar energy: in the form of heat
Gravitational potential energy: causes rivers to flow downhill and precipitation to fall to the ground.
What are stores
reservoirs where water is held.
Name the 4 main stores
the oceans (largest by far)
glaciers and ice sheets (cryosphere, second largest)
surface runoff- land-based stores, including rivers, lakes, groundwater and the moisture held in soils and vegetation.
the atmosphere
Of the freshwater stores:
The cryosphere is the largest, holding 69% of global freshwater
Groundwater holds 30%
Less than 1% is stored in the biosphere (vegetation and soil moisture)
What are flows
transfers of water from one store to another.
What are fluxes
rates of flow between stores -> greatest fluxes occur over the oceans.
What does the global water budget do
limits water available for human use
What is the main input of the hydrological cycle
precipitation
Name 5 characteryics that effect the drainage cycle
Form: rain, snow or hail. Clearly, with snow, entry of water into the drainage system will be delayed.
Amount: this will affect the amount of water in the drainage basin and the fluxes within it.
Intensity: the greater the intensity, the greater the likelihood of flooding.
Seasonality: this is likely to result in the drainage basin system operating at different flow levels at different times of the year.
Distribution: this is significant in very large drainage basins, such as the Nile and the Ganges, where tributaries start in different climate zones.
Name the 7 different flows important in transferring the precipitation that has fallen on land
-interception
-Infiltration
-percolation; deep tranfer of water into permeable rocks
-throughflow; lateral transfer of water downslope through soil
-groundwater flow; v slow transfer of percolated water through porous rocks
-surface runoff; when water accumulates in soil until water table reaches surface, forcing further rainwater to run off surface
-river or channel flow
What is interception
retention of water by plants and soils -> evaporated/ absorbed by the vegetation.
What is infiltration
the process by which water soaks into, or is absorbed by, the soil.
What is percolation
a deeper transfer of water into permeable rocks.
What is throughflow
lateral transfer of water downslope through the soil
What is groundwater flow
very slow transfer of percolated water through pervious (permeable) or porous rocks.
What is surface runoff
movement of water that is unconfined by a channel across the surface of the ground. A.k.a. overland flow.
What is river/ channel flow
takes over as soon as the water enters a river or stream; the flow is confined within a channel.
Name the 3 output processes
-evaporation
-transpiration
-discharge
What is evaporation
when moisture is lost -> atmosphere from water surfaces, soil and rock.
What is transpiration
biological process -> water is lost from plants through minute pores and transferred to the atmosphere.
What is discharge
the volume of water passing a given point over a set of time
What is a drainage basin
area of land drained by a river and its tributaries with a boundary (wtaershed)
-area of land where when water falls on it -> flows into river
What is the watershed
boundary of a drainage basin
What kind of system is the drainage basin
open
Name 5 factors that affect the drainage basin system
-climate
-soils
-geology
-relief
-vegetation
How does climate affect drainage basin
-impacts on the inputs and outputs
-influences type & amount of precipitation overall & amount of evaporation
How do soils affect the drainage basin
affect relative importance of different flows within system ( most important is surface runoff)
Soils determine the amount of infiltration and throughflow, the type of vegetation
How does geology affect drainage basin
affects relative importance of different flows within the system ( most important is surface runoff)
Geology can impact on subsurface processes such as percolation and groundwater flow (and, therefore, on aquifers)
Indirectly, geology affects soil formation.
How does relief affect the drainage basin
affects the relative importance of different flows within system ( the most important is surface runoff)
Relief can impact on the amount of precipitation.
Slopes can affect the amount of runoff.
How does vegetation affect drainage basins
Largely affects relative importance of the different flows within the system (most important is surface runoff)
presence/ absence of vegetation has impact on amount of interception, infiltration and occurrence of overland flow, as well as on transpiration rates.
How do humans disrupt the drainage basin
deforestation- no vegetation -> no interception -> rain strikes soil directly -> soil compaction
-rain doesn’t soak into soil -> stays on surface -> surface runoff -> erosion
changing land use -> urban areas -> infiltration reduces -> larger surface run off -> less evapotranspiration
creating new water storage reservoirs - interrupt natural flows of water -> delays flows -> ^ evaporation
what is the hydrological cycle driven by
it is driven by solar energy and gravitational potential energy.
1) solar energy- has water and turns from a liquid to a gas, rises into the atmosphere and cools and condenses to form clouds
2)gravitational potential- earth’s gravity pull is converted into kinetic energy and accelerates water through the cycle (falling as precipitation, flowing across the land, infiltrating and percolating)
Name the inputs to the drainage system
precipitation patterns and types:
- orographic
- frontal
- convectional
vary in a number of different ways. by form (rain, snow, hail), amount, intensity, seasonality, distribution
what are the outputs in the drainage basin?
evaporation- moisture lost into atmosphere from water surfaces, soil and rock
transpiration- biological process -> water is lost from plants through minute pores and transferred into the atmosphere
discharge (channel flow)- into another, larger drainage basin, a rivulet, lake or the sea, the amount depends on the amount of precipitation falling directly into the channel
what type of system is a drainage basin?
it is an open system. it has inputs and outputs.
Name the stores in the drainage basin
Soil Water - Water stored in the soil which is utilised by plants - Mid-term
Groundwater - Water that is stored in the pore spaces of rock - Long-term
River Channel - Water that is stored in a river - Short-term
Interception - Water intercepted by plants on their branches and leaves before reaching the
ground - Short-term
Surface Storage - Water stored in puddles, ponds, lakes etc. - Variable
what is orographic precipitation
orographic uplift -> uplift of an air mass, because of orographic obstruction, -> cooling of air mass
if enough cooling occurs -> condensation occurs -> orographic precipitation, in mountains, hills
what is frontal precipitation
caused when warm air meets cold air & forces warm air to rise -> cool -> condense -> forming clouds -> rain
what is convectional precipitation?
caused when moisture evaporates & rises when heated by the sun in warm areas -> cools -> condenses -> forms cloud -> rains
What does the global water budget take account for
all the water that is held in stores and flows of the global hydrological cycle.
What is fossil water
Ancient, deep groundwater made from pluvial (wetter) periods in the geological past
What is the water budget
-oceans lose more water from evaporation than precipitation
-surface runoff makes up difference -> balancing it out
-if balance was disturbed -> oceans would recieve more water - continents would dry
-water budget is this balance
water:
-how much water in oceans
-freshwater?
-ice caps and glaciers?
-groundwtaer?
-surface water?
-lakes?
-soil moisture?
-atmsopheric water vapour?
-rivers?
-accessible water in plants
-97.5% oceans
-2.5% freshwater
69% in ice caps and glaciers
30% in groundwater
1% as easily accessible surface water
52% in lakes
38% as soil moisture
8% as atmospheric water vapour
1% in rivers
1% as accessible water in plants
Why are drainage basins referred to as an open system
-as they lose more than they receive
-lose water by:
-evaporation, evapotranspiration to atmosphere
-surface runoff to the sea
-percolation into groundwater stores
What is an aquifer
underground reservoir
Q
what is the cryosphere and biosphere?
cryosphere- the ice system (ice sheets and glaciers)
biosphere- the living system (plants and animals)
what is a residence time
how long water stays in a particular store
-larger the store, the longer the residence time
Name the 3 conditions needed for precipitation to form
-air cooled to saturation point
-consensation nuclei
-temperature below dew point
What is blue water
freshwater stored in rivers, streams, lakes -> visible part of hydrological cycle
What is green water
freshwater stored in the soil and vegetation -> invisible part of hydrological cycle
Name 2 reasons why water budgets are useful
-can be used to monitor amount of water held in stores
-base flow provides info on the usually avaliable water
Name 3 ways humans have accelerated the process of desertification
-overpopulation
-environmental degradation resulting from overgrazing
-deforestation
