WCC Flashcards
what is systems theory
views the world as a complex system of interconnected parts
what is a system
a process or collection of processes that transforms inputs into outputs
what 3 kinds of properties are found within a systems bounderies
elements - the physical parts that make up a system, eg sand
attributes - characteristics of the elements that can be perceived or measured
relationships - the associations between elements and attributes, based on cause and effect
what is an open system?
a system in which both matter and energy are able to transfer across the system boundary
what is a closed system?
a system in which only energy, not matter, is able to be transfered across the system boundery
what is dynamic equilibrium
the balanced state of a system when it’s inputs and outputs are equal
what is a feedback mechanism
a process that uses the conditions of one component to regulate the function of another, in order to regain equilibrium
what is a positive feedback mechanism?
when the process tends to increase the change in the system
what is negative feedback?
when the process seems to counter the change and maintain equilibrium
what are elements
the things that make up the system
what are flows/transfers
links between stores or components, along which something moves
what is the system boundary?
the edge of the system, the interface between one system and another
what is a store/component
a part of a system where something is held for a period of time
what are attributes?
the characteristics of the elements of a system (eg. hot/cold)
what is an input
a point where something is added to a system
what is an output?
a point were something is removed from the system
what kind of system is the hydrological cycle?
a closed system, as no water is lost to or gained from space
what kind of system is the drainage basin system?
an open system, as water is able to flow into and out of the system boundery
where is water stored?
hydrosphere - liquid water
cryosphere - snow or ice
atmosphere - the layer of gas between the earths surface and space
biosphere - water contained in living things
what are underground reservoirs known as?
aquifers
what percentage of fresh water is contained in aquifers?
30%
when does relief rainfall occur?
when warm moist air rises up over mountains, then cools and condenses to form clouds
when does frontal rainfall occur?
when a warm front meets a cold front, the heavier cold air sinks to the ground and the lighter warm air rises above it, then could and condenses to form clouds, which bring rain
when does conventional rainfall occur?
when the land warms up, it heats the air above it, which then rises, cools and condenses to form clouds, which bring rain
what is precipitation
transfer of water from the atmosphere to the ground, in the form of rain, snow, hail sleet or dew
what is evaporation
the transfer of water from liquid surface water to the atmosphere
what is evapotranspiration
the transfer of water from the earth’s surface to the atmosphere by the combined efforts of evaporation and transpiration
what is condensation
the transfer of water from a gaseous state to a liquid state, eg cloud formation
what is sublimation
transfer of water from a solid state to a gaseous state and vice versa
what is interception
water intercepted from precipitation by and stored on the leaves of plants
what is overland flow?
flow of water over the land surface, also known as surface run off
what is infiltration?
the flow of water from the ground surface into soil
what is throughflow?
water flowing through the soil towards a river channel
what is percolation?
water flowing downwards from the soil into the underlying rocks
what is groundwater flow?
the flow of water very slowly through rocks deep underground
how long does water remain in glaciers?
10-10,000 years
how long does water remain as soil moisture?
2 weeks to 1 year
how long does water remain as shallow groundwater?
100-200 years
how long does water remain as deep groundwater?
10,000 years
how long is water stored in oceans?
4,000 years
how long is water stored in lakes?
10-100 years
how long is water stored in the atmosphere?
10 days
how long is water stored in rivers?
2 weeks to 6 months
how long is water stored in the biosphere?
1 week
if all the polar ice sheets melted, how much would sea levels rise?
60m
what percentage of water is stored in the hydrosphere (liquid water)?
96.5%
what percentage of water is stored in the cryosphere (frozen water)?
1.7%
what percentage of water is stored in the atmosphere (gaseous water vapor)
0.001%
what percentage of water is stored in the lithosphere (groundwater)
1.7%
how does climate change affect the magnitude of water stores?
-melts cryospheric stores
-meltwater increases hydrospheric stores
-at the peak of the last ice age 1/3rd of the earth’s surface was covered by glaciers and ice sheets and sea levels were 100m lower
how do cryosphric processes affect the magnitude of water stores?
-snow falling on ice sheets gets compressed and enters long term storage, increasing cryospheric stores
-melting ice in the summer decreases cryospheric stores
-melting and snowfall are usually in equilibrium but climate change is changing this
how does evaporation change the magnitude of water stores?
-transfers water from hydrospheric stores to atmospheric stores
-aprox 90% of atmospheric water is from evaporation and 10% is from transpiration
-high levels of evaporation can occur in tropical and desert areas - regional scale changes
-large regional scale impact
how does condensation affect the magnitude of water stores?
-water vapour changes back into a liquid state within the atmospheric water store
-no direct change to the magnitude of stores, but leads to cloud formation and precipitation
-
