Y12 MB - Water Cycle (Complete) Flashcards
What is the definition of a system?
A set of inter-related components which work together towards a process
What are systems composed of?
Inputs, outputs, stores, flows / transfers and boundaries
What is an input?
When matter or energy is added to a system
What is an output?
When matter or energy leaves a system
What is a store?
Where matter or energy builds up in a system
What is a flow / transfer?
Where matter or energy moves in a system
What is a boundary?
The limit to a system (e.g a watershed)
What are the three types of system?
Open, closed and isolated
What is an open system?
Systems where matter and energy can change and move in and out
What is a closed system?
Systems where energy can change and move in and out but matter can only cycle through stores and stays the same
Give an example of an open system
Carbon - Woodland
Water - Drainage basin
Give an example of a closed system
Carbon - Global carbon cycle
Water - Global water cycle
What is dynamic equilibrium?
When there is a balance between inputs and outputs of a system
What generally determines whether a system is open or closed?
Scale (e.g the global water cycle is a closed system whereas a drainage basin is closed)
What happens to a natural system if there is a change?
The system works to regain equilibrium through natural conditions
What is feedback?
The knock-on effect of something happening (e.g a change in the balance of inputs and outputs of a system)
What is positive feedback?
Where the knock-on effects of a change are amplified
What is negative feedback?
Where the knock-on effects of a change are nullified
What kind of system can the earth be classed as?
A closed system
What are the five subsystems of the Earth?
Lithosphere
Cryosphere
Biosphere
Hydrosphere
Atmosphere
What is the lithosphere?
The outermost layer of the earth (the crust and upper mantel)
What is the biosphere?
The biological component of the earth (all living things)
What is the atmosphere?
The layer of gas between the Earth’s surface and space
What is the hydrosphere?
All of the water on earth, saline and fresh (e.g rivers + lakes, water vapour and solid water)
What is the cryosphere?
The part of the Earth where water is frozen
What is precipitation?
All forms of moisture which reach the Earth’s surface e.g rain, snow
What is interception?
When precipitation meets vegetation, concrete or buildings before it reaches the soil. Interception stores only last for a short period of time as they often evaporate quickly
What is vegetation storage?
Water taken up by vegetation. All of the moisture stored in vegetation at one time
What is surface storage?
All of the water held on the Earth’s surface at one time e.g in puddles, ponds and lakes
What is groundwater storage?
The storage of water underground in permeable rock strata
What is channel storage?
The water held by rivers or stream channels
What is baseflow?
The groundwater flow that feeds into rivers through river banks and river beds
What is groundwater flow?
The movement of water through the permeable rock strata below the water table
What is channel flow?
The movement of water through a river channel
What is infiltration?
The downward movement of water into the soil surface
What is interflow?
Water flowing downhill through permeable rock above the water table
What is percolation?
Water moving downwards through soil and bedrock below the water table due to gravity
What is stemflow?
Water running down a plant stem or tree trunk
What is surface runoff?
The movement of water over the surface of the land, usually when the ground is saturated or frozen or when precipitation is too intense for infiltration to occur
What is throughflow?
The lateral movement of water within the soil layer. This is significantly fast through ‘pipes’ e.g cracks in the soil or animal burrows
What is evaporation?
The transformation of water from droplets to vapour through heating
What is evapotranspiration?
The loss of water from a drainage basin into the atmosphere from the leaves of plants as well as evaporation
What is transpiration?
Evaporation from plant leaves
What is river discharge?
The volume of water which passes a point in a given time
What is sublimation?
The transformation of water from a solid to a gas
What is deposition?
The transformation of water from a gas to a solid
What percentage of the Earth’s water is in the oceans?
96.5%
What is orographic / relief precipitation?
When air is forced to rise over highland and cools causing condensation and so precipitation
What is frontal precipitation?
When a mass of cold, dense air meets a mass of warm, less dense air. The warmer, less dense air is forced to rise and so condensation and precipitation occurs
What is conventional precipitation?
When the sun’s rays heat the Earth’s surface, causing water to evaporate and rise. This then cools causing condensation and so precipitation
What is a drainage basin?
An area of land drained by a river and its tributaries
What is a water shed?
The boundary around a water basin often marked by a ridge of high land
What is a confluence?
Where a river joins another river channel
What is a tributary?
Where a smaller river joins a larger river channel
What is the source?
The furthest point from the mouth / confluence
What is the mouth?
Where the river meets the sea / lake
What is the ITCZ?
Inter-tropical convergence zone
What is the water table?
The level where water has saturated the ground
Aquifer
A vast underground reservoir most commonly formed in rocks such as chalk and sandstone
Soil moisture budget
Describes the changes in the soil water store during the course of the year. It is determined by evapotranspiration and precipitation
Soil moisture utilisation
The extraction of soil moisture by plants for their needs
Soil moisture deficit
The point at which the soil moisture falls below field capacity, caused by a lack of precipitation and high amounts of evapotranspiration
Soil moisture recharge
Following soil moisture deficit, precipitation is greater than potential evapotranspiration so moisture will be added to the soil
Field capacity
The point at which the soil becomes saturated
Soil moisture surplus
The period when the soil is saturated so water cannot enter and therefore it flows over the surface. This is caused by low levels of evapotranspiration and high levels of precipitation
Soil porosity
Pores or small spaces in the soil. The more pores, the more water can be stored in the soil
The Water Balance
An equation used to express the amount of water in each of the water stores (the different spheres)
Hillslope system
The way in which water moves down a typical hillslope and towards a river, involving stores and transfers
Irrigation
The supply of water to the land by means of channels, streams and sprinklers in order to permit the growth of crops
Water abstraction
The extraction of water from rivers or underground aquifers
Salt water intrusion
The movement of saltwater into an aquifer, which may cause contamination. Often caused by over abstraction of groundwater from an aquifer
Ablation
Outputs from a glacial system due to melting (size of glacier decreases)
Accumulation
Inputs to a glacial system due to snowfall (size of glacier increases)
Antedecent rainfall
Precipitation that has fallen before
