water and carbon Flashcards
What is the definition of an open system
Both energy and matter can enter and leave
What is an example of an open system
Drainage basin:
Energy from the sun enters and leaves the system. Water is input as precipitation, and output as river discharge into the sea
What is the definition of a closed system
Matter cant enter or leave, it can only cycle between stores
Energy can enter and leave a closed system- it can be input or output
What is an example of a closed system
The carbon cycle is a closed system-energy is input from the sun in photosynthesis and output through respiration. But the amount of carbon on Earth stays the same because there are no inputs or outputs of matter
What is dynamic equilibrium
Small variations in inputs and outputs that remain balanced on average.
What is positive feedback
Amplify the change in the inputs or outputs. This means that the system responds by increasing the effects of the change, moving the system even further from its previous state.
What is an example of positive feedback
- Temperatures rise
- Ice covering cold parts of Earth melts due to higher temperatures
- Less ice cover means less of the Sun’s energy is reflected
- Less of Sun’s energy being reflected means more is absorbed by the Earth
–> temperature rises
What is negative feedback
Counteracts the change in the inputs and outputs
This means that the system responds by decreasing the effects of the change, keeping the system closer to its previous state.
What is an example of negative feedback
- Large amounts of co2 emitted
- co2 in atmosphere increases
- extra co2 causes plants to increase growth
- Plants remove and store more co2 from the atmosphere
- Amount of co2 in atmosphere reduces
What are the subsystems of the earth
cryosphere
lithosphere
biosphere
hydrosphere
atmosphere
What is the cryosphere
Includes all parts of the earths system where its cold enough for water to freeze
e.g glacial landscapes
What is the lithosphere
the outermost part of the earth. it includes the crust and the upper parts of the mantle
What is the biosphere
It is part of the earths system where living things are found. It includes all the living parts of earth- plants, animals, fungi, bacteria
What is the hydrosphere
It includes all the water on earth. It may be in liquid form (lakes), solid form(ice stored in the cryosphere) or gas form (water vapour stored in the atmosphere)
It can also be saline or fresh
What is the atmosphere
The atmosphere is the layer of gas between the earth’s surface and space, held in place by gravity.
How much of the earths water is freshwater
3%
Of earths fresh water…….
69% is frozen in the cryosphere
30% is groundwater
0.3% is liquid freshwater on the earth’s surface in lakes and rivers etc.
0.04% is stored as water vapour in the atmosphere
What is evaporation and what causes it to change in magnitude
When liquid water changes state into a gas, becoming water vapour- it gains energy, normally from solar radiation. This increases the amount of water in the atmosphere
If there’s lots of solar radiation, a large supply of water and warm, dry air, the amount of evaporation will be high
If there is not much solar radiation, little available liquid water and cool air that is already nearly saturated, evaporation will be slow
What is condensation and what causes it to change in magnitude
Condensation occurs when water vapour changes state to become liquid- it loses energy to the surroundings. It happens when air containing water vapour cools to its dew point.
Water droplets can stay in the atmosphere or flow to other subsystems. This decreases the amount of water stored in the atmosphere.
The magnitude of the condensation flow depends on the amount of water vapour in the atmosphere and the temperature.
What is the main flow of water from the atmosphere to the ground
precipitation
How are clouds formed
warm air cools down, causing water vapour in it to condense into water droplets, which gather as clouds. When droplets are big enough they fall as precipitation.
What is a drainage basin
area surrounding the river where the rain falling on the land flows into the river
What are the inputs of a drainage basin
Precipitation
What are the stores in a drainage basin
Interception
Vegetation storage
Surface storage-puddles, ponds, lakes
Soil storage
Ground water storage- the water table is the top surface of the zone of saturation
Channel storage-water held in a river or stream channel
What are the flows in a drainage basin
Infiltration-influenced by soil type, soil structure, soil saturation
Overland flow-rain falls on the ground faster that infiltration can occur
throughfall-water dripping from leaf to leaf
Stemflow
Percolation-water seeping down soil into the water table
Groundwater flow-flow below the water table through permeable rock
What are the outputs of a drainage basin
Evaporation
Transpiration-evaporation within leaves
Evapotranspiration-evaporation and transpiration together
river discharge
What is potential evapotranspiration
Amount of water that could be lost by evapotranspiration.
Actual evapotranspiration is what actually happens.
For example in a desert potential evapotranspiration is high because of the heat but actual transpiration is low because there isnt much moisture
What is the water balance
Changes in inputs and outputs and affects how much water is stored in the basin
Outline seasonal changes in the water balance.
In wet seasons, precipitation is higher than evapotranspiration.
This creates a water surplus
In dry seasons precipitation is lower than evapotranspiration
and water in the ground store is depleted
This leads to a water deficit
What is a hydrograph
Show a river discharge over a period of time
What is river discharge
Volume of water that flows in a river per second
What does a hydrograph include
lag time
rising limb
peak rainfall
peak discharge
falling limb
What is peak discharge
this is the highest point on the graph, when the river discharge is at its greatest
What is lag time
This is the delay between peak rainfall and peak discharge.
This delay happens because it takes time for rainwater to flow into the river
What is rising limb
part of the graph up to peak discharge
What is falling limb
after peak discharge.
decreasing as less water flowing into the river
What are the features of a flashy hydrograph
Short lag time
steep rising and falling limb
high flood risk
high peak discharge
What are the features of a subdued hydrograph
long lag time
gradually rising and falling limb
lower flood risk
low peak discharge
What factors affect the shape of a hydrograph and runoff
size of drainage basin
shape of drainage basin
ground steepness
rock and soil type
How does size of drainage basin effect the hydrograph
large ones catch more precipitation, so have a higher peak discharge.
Smaller basins generally have shorter lag times because precipitation has less distance to travel, so reaches the main channel quicker
How does shape of a drainage basin affect a hydrograph
circular basins have flashy hydrographs as all the points on the watershed are equidistant to the point of discharge measurement
How does ground steepness effect a hydrograph
water flows quicker downhill shortening lag time.
Also means that water has less time to infiltrate the soil, so runoff is higher
How does rock and soil type affect a hydrograph
impermeable rocks and soils dont store water so more surface runoff
Peak discharge also increases as more water goes to the river
