Water Flashcards
what is a store
reservoirs are where water is stores, these can be in form of oceans, river, aquifers ect
what is a flux
how water is transferred between stores
what are processes
physical mechanisms which drive fluxes of water between stores
solar and GPE
what is the cryosphere
areas of earth where water is frozen into snow/ice (during last ice age sea levels were 140m lower than today)
what is a systems approach
approaches that study hydrological phenomena by looking at balance of inputs and outputs and how water is moved between stores and flows
what is an open system
recieves inputs from + transfers outputs of energy to other systems eg) drainage basins
what is a closed system
fixed amount of water or earth + atmosphere system (1385million km^3) there are no external inputs/outputs and the system remains constant
what is blue water
water that is stored in rivers, streams, lakes and groundwater in liquid form
what is green water
water stored in soil and vegetation
what proportion of worlds water is stored in:
- Oceans
- freshwater
- saline
Oceans- 96.5%
Fresh- 2.5%
Saline- 0.9%
Of the 2.5% freshwater, how much is stored in the cryosphere and groundwater
- 7% Glaciers
30. 1% ground water this includes atmosphere, rivers swamps, soil moisture and living things
how much of the groundwater water is stored in rivers?
0.49% less than in swamps which is 2.6%
Examples of fluxes
evaporation rain/precipitation snowfall percolation overland flow interception
examples of stores
sea/ ocean ice lakes river soil moisture swamps
what is the water budget
annual balance of water fluxes (flows) ad size of water stores
is water considered a renewable source
water stores have different residence times (amount of time the water is held for) but it is generally considered renewable
what 2 places might water not be considered renewable
fossil water and cryosphere
what is fossil water
untapped ancient stores of freshwater that exist in polar regions or beneath deserts in the form of aquifers
eg) Kenyas lotihipi aquifer which contains est. 200 billion cubic meters of saline water)
how is the cryosphere non renewable source of water
major ice sheets store water for very long periods such as Greenland and Antarctica
ice core dating has found that some water in Antarctica is over 800,000 years old
69% locked up in snowflakes ice sheets and icecaps and glaciers in high altitudes and latitudes where inaccessible to humans
what are the2 processes driving the hydrological cycle
solar energy and GPE
how does solar energy drive the water cycle
energy from sun heats+causes evaporation/transpiration more as climate warms globally which increases moisture levels in atmosphere
this can lead to more condensation as air cools so more rain
how does Gravitational potential energy drive water cycle
keeps water accelerating through system under influence of gravity
on land energy is converted to kinetic as water moves through system by plant inception/ overland flow surface run-off
where is solar energy concentrated the most?
in the tropics where much of it is absorbed by the sea
»> this produces high rainfall 74% of rainfall is in sea in tropics, the rest of the worlds rainfall is unevenly distributed
»>seasonal monsoons in asia and africa which contrasts with climate in NW europe
(different climatic regions differ in inputs, nature and size of transfers, and flows of water)
describe characteristics of polar hydrology
> permafrost creates impermable surfaces
winter snow insultes ground and causes 85% of solar radiation to be reflected
freeze thaw cycles in spring cause rapid surface run-off
and release of bigenic gases to atmosphere
what is the annual precipitation in polar regions
200mm or less
what kind of rainfall generally occurs in polar regions
orographic or frontal
low humidity
describe characteristics of of tropical rainforest hydrology
> constant high temps and 50-75% of rainfall returns by evaportransiration
75% of precipitation consumed by trees
less than 25% of rainfall reaches the rivers or other surface water
few seasonal variations
evapotranspiration cools the air as energy is used during the process
whats the annual precipitation in the rainforest
2000mm
what kind of rainfall occurs in the rainforests
convectional rainfall and high humidity
how will deforestation effect the rainforest
reduces evapotranspiration and therfore vapor and local rainfall
explain how the hydrological cycle is a closed system
A closed system is one with a fixed amount of water on the earth and atmospheric system
1) evaporation, clouds , precipitation restarts cycle again
2) ground water added from other stores through things like percolation. groundwater transfers to ocean stores where it is evaporated again and returns to groundwater as rain.
in order for rain to form what things must there be?
- air cooled to saturation point w/ 100% humidity
- condensation nuclei such as dust particles to facilitate the growth of water droplets in clouds
- temp below dew point
What is the saturation point
no more substance can be absorbed into vapor
what is the dew point
as temp drops and objects cool down, air becomes cooler around object, colder air less able to hold vapor than warm air which causes condensing of air to water
what is frontal rainfall and how is it formed
> when warm lighter air is forced to rise over colder denser air
as it rises the air cools and its ability to hold water vapor decreases
condensation occurs and clouds form and rain forms
what is convectional rain and how does it form
> when the land becomes hot, air above it becomes warmer, expands and rises
as it rises the air cools and its ability to hold water decreases
condensation occurs and clouds develop
if the air continues to rise, the rain will fall
what is orographic rain
> when air is forced to rise over a barrier such as a mountain and cools and condenses
clouds form and precipitation occurs on the leeward (downwind) slope which recieves relatively little rain which is known as the ‘rain shadows effect’
east of england is dryer because of this
what is interception
process in which water is stored in vegetation:
1) interception loss (water retained by plants)
2) through fall (when water drops from leaves)
3) stem flow (water trickles along branches/stems)
what is infiltration
and what is infiltration capacity
process of water being absorbed by soil
>max rate of rain that is absorbed and depends on the saturation level and slope angle
what is direct runoff
water travelling on surface of ground
what is saturated overland flow
slower transfer of water caused by water table rising to the surface caused by succession of winter storms
what is through flow
lateral transfer of water downslope through soil below the surface but above the water table
what is percolation
deeper transfer of water into permeable rocks eg sandstone/chalk
what is groundwater flow
aka base flow, This is the very slow transfer of percolated water through pervious/ porous rock
what are 3 outputs to the water cycle
- evaporation- moisture directly lost to atmosphere from water surfaces and soil as a result of suns heat
- transpiration- (or evapotranspiration) a biological process where water is lost from plants to atmosphere
- channel flow- (river discharge) volume of water flowing within a river channel
which factors effect the outputs to the water cycle
- hours of sunlight
- temperature
- size and depth of water
- surface colour
- humidity
- wind speed
- vegetation cover
what is a drainage basin defined as
an area of land drained by a river and its tributaries and can be referred to as a river catchment area.
at a local scale, hydrological processes operate within these areas and it is an open system which has inputs and outputs which causes the amount of water to vary.
what are the physical factors which infleunce a drainage basin
Climate Soils Geology Relief Vegetation
how does climate effect a drainage basin
role in influencing the amount of precipitation overall and the amount of evaporation. This also has an impact on vegetation
how do soils effect a drainage basin
determines the amount infiltration, through flow and indirectly, the type of vegetation
how does geology effect a drainage basin
This can impact subsurface processes such percolation and ground waterflow (and therefore aquifers) It can indirectly alter soil formation
how does relief effect a drainage basin
Altitude can impact on precipitation totals. Slopes can effect the amount of runoff
how does vegetation effect a drainage basin
Presence/absence has impact on rate of interception, infiltration and occurrence of overland flows as well as transpiration
how have physical factors effected the hydrological cycle in an arid environment
- lower altitude near equator in an area of higher pressure so recieves little rain
- therefore there is little vegetation cover and less soil
- sand geology means water can percolate through so there is very little residence time. Low altitude so little surface run-off
