Systems in physical geography Flashcards
Input
Material or energy moving into system from outside
Examples
Drainage basin-precipitation
Woodland-precipitation with dissolved carbon dioxide
Output
Material or energy moving from the system to the outside
Examples
Drainage basin-runoff
Woodland-dissolved carbon within runoff
Energy
Power or driving force
Examples
Drainage basin-latent heat associated with changes in the state of water
Woodland-production of glucose through the process of photosynthesis
Stores/components
The individual elements or parts of a system
Examples
Drainage basin-trees, puddles, soil
Woodland-trees, soil, rocks
Flows/transfers
The links or relationships between the components
Examples
Drainage basin-infiltration, groundwater flow, evaporation
Woodland-burning, absorption
Positive feedback
Cyclical sequence of events that increases change, exacerbate the outputs of a system, promoting environmental instability
Examples
Drainage basin-rising sea levels destabilise ice shelves, increasing rate of calving, increase in melting, further rising
Woodland-increased temp from melting permafrost, greenhouse gases released, enhancing greenhouse effect, raising temps
Negative feedback
A cyclical sequence of events that neutralises the effects of a system, promoting stability and a state of dynamic equilibrium
Examples
Drainage basin-surface temps increase, sea evaporation increase, more cloud cover, reflect radiation, slight cooling
Woodland-increased atmosphere co2, increased temp, increased plant growth and photosynthesis, removes more co2 from air, counteracting rise in temp
Dynamic equilibrium
Represents a state of balance within a constantly changing system
Examples
Remote and unaffected drainage basin/woodland where there has been no significant natural or human impacts, or one that has had time to adjust to change
Water cycle system
Closed system on the whole, at a small scale is open system e.g. drainage basin, precipitation is an input and runoff to oceans is an output
Carbon cycle system
Closed system, local scale such as forest is an open system
Main stores in water cycle
Lithosphere, hydrosphere, cryosphere, atmosphere
96.6% of all water is oceans
2.5% freshwater, majority ice and groundwater
1.2% of all freshwater is surface water
Not evenly distributed
Aquifers
A body of saturated rock through which water can easily move through
Form in porous and permeable rock e.g. chalk and sandstone
Water enters quickly when the rock exposed or slowly as water drains through overlying soil
Soil water budget
Soil capacity to store and transfer water
E.g. sandy soils hold little moisture and water is easily transferred, clay soils store water and have limited transfer
Water table
Upper level of saturated rock, rises and falls in response to groundwater flow, water abstraction or by recharge (additional water flowing into rock)
Needs to be maintained at state of equilibrium
Fossil aquifers
Aquifers in deserts of Africa, Middle East, formed thousands of years ago when climate much wetter.
Many being exploited unsustainably as water extracted
