Water cycles Flashcards
What is an input?
matter & energy added to the system
What is an output?
matter & energy leaves the system
What is a store?
matter or energy building up in the system
What is a flow?
matter or energy moving in the system
What is an open system?
matter & energy transferred from the system into the surrounding environment
What is a boundary?
limits to the system?
What is a closed system?
only energy transferred in and out of the system (not matter)
What is an isolated system?
no interactions with anything outside the system boundary
What is equilibrium?
inputs = outputs
What is dynamic equilibrium?
when (almost) inputs=outputs
Definition of positive feedback:
mechanisms that amplify the change in inputs and outputs
Example of positive feedback:
when surface temperature rises, part of the ice and snow melts, leading to an increase in the solar radiation
Definition of negative feedback:
mechanisms that counteract/nullify the change in inputs and outputs
What is the cryosphere?
glacial landscapes (cold enough for water to freeze)
Example of negative feedback:
an increase in temperature increases the amount of cloud cover, reducing incoming solar radiation which limits global warming
What is the lithosphere?
the outermost part of the earth, including the crust and upper parts of the mantle
What is the biosphere?
living things (plants & animals)
What is the hydrosphere?
all water on the earth
What is the atmosphere?
a layer of gas between Earth’s surface and space
Why are the sub-systems cascading?
because one effects another
How much freshwater is in the lithosphere?
30%
How much freshwater is in the hydrosphere?
0.3%
How much freshwater is in the atmosphere?
0.04%
How much freshwater is in the cryosphere?
69%
How much freshwater is in the biosphere?
0.26%
How much of the earth’s water is freshwater?
2.5%
What are the 3 types of precipitation? (Inputs)
relief, convectional, frotal
Name 2 outputs
evapotranspiration and streamflow
Name 7 flows
infiltration, percolation, throughflow, surface runoff, groundwater flow, streamflow, stemflow
Name 5 stores
soil water, groundwater, river channel, interception, surface storage
Example of a boundary:
watershed
What is the equation for the water balance?
precipitation = total runoff + evapotranspiration +/- (change in) storage
What are changes to the drainage basin?
urbanisation, agriculture, seasonal change, deforestation, storms
What are cryospheric processes on a local scale?
snow builds up overtime, compressed onto ice, held in storage (the glacier) then as the altitude increases, the temperature decreases melting the glacier
What are cryospheric processes on a global scale?
“Albedo effect”, snow and ice reflects the suns energy, land and oceans absorb the suns energy
What are cryospheric processes in the long term?
ice melts quickly, water “locked up” in ice sheets and glaciers, means sea levels decrease by 100m compared to present day (during the ice age)
What are short term cryospheric processes?
winter = snow is accumulated, summer = melting occurs, the equilibrium line means glaciers are shrinking as it moves higher
What is the Gulf Stream?
thermohaline circulation example
What does warm water do (gulf stream)
lower density = rises = more salty
What does cold water do (gulf stream)
higher density = sinks = less salty
Examples of human and physical changes to the water cycle:
- deforestation
- storm events
- seasonal changes
- agriculture
- urbanisation
What is soil recharge?
when the water table increases in response to high rates of precipitation, following a period of water deficit
Examples of natural processes (changes overtime of the water cycle):
- seasonal changes
- storm events
- droughts
- El Nino effect
- La Nina effect
What is the El Nino effect?
2-7 year occurance, warm temperatures in a predictable way
What is the La Nina effect?
2-7 year occurance, cold temperatures in a predictable way
What is peak discharge?
the point of greatest discharge
What is lag time?
the difference between peak rainfall and peak discharge
What is peak rainfall?
greatest point of rainfall
What is the rising limb on a flood hydrograph?
the discharge increasing
What is the falling limb on a flood hydrograph?
the discharge decreasing
What is bankfull discharge?
the level of discharge where the river has reached its peak (if more rainfall happens, the river will flood)
What is storm flow?
water in the river that is above the base flow
What is baseflow?
the standard level of water (discharge) that a river has
What makes a river “flashy”?
when it is likely to flood
Factors effecting short lag time:
- steep slopes
- urbanisation
- small drainage basin
- saturated soil
- heavy prolonged rainfall
- low drainage density
Factors effecting long lag time:
- dry soil
- gentle slopes
- high drainage density
- large drainage basin
- permeable rocks
- woodland / forest
- light rain over a long period of time
Physical factors effecting flood hydrographs:
- size of drainage basin
- shape of basin
- ground steepness
- soil and rock type
Water cycle factors effecting flood hydrographs:
- intense storms
- large inputs
- infiltration
- changes in vegetation
Human factors effecting flood hydrographs:
- ploughing
- livestock
- irrigation
- new buildings / urbanisation
- abstraction
