Water cycle Flashcards
Define a system.
A number of components, between which there are links.
In a system, what is transferred between the components?
Energy.
What 2 quantities exist within a system?
Energy and mass
What does the term ‘mass balance’ mean in systems theory?
The amount of mass in a system.
What are inputs in systems theory?
The transfer of any energy or mass into the system from its surroundings.
What are outputs in systems theory?
The transfer of any energy or mass out of the system into its surroundings.
What is a store in systems theory?
An accumulation of energy or mass.
What is a flow in systems theory?
The movement of energy and matter between 2 stores.
What are 2 other terms for ‘flow’ in systems theory?
- Flux
2. Transfer
What is a boundary in systems theory?
The external limit of the system; everything within its limits is in the system. The boundary distinguishes the system from its surroundings.
In systems theory, a system is bounded by what 2 things?
Space and time.
What is an element in systems theory?
Any part which makes up the system.
What is another term for ‘element’ in systems theory?
Component
What is an attribute in systems theory?
A measurable or perceivable characteristic of an element.
What are the 3 types of system?
- Isolated system
- Closed system
- Open system
What distinguishes between the 3 types of system?
Their inputs and outputs.
What is an isolated system in systems theory?
A system with no inputs or outputs. No energy or matter either enters or leaves the system.
Use 1 word to describe the energy balance and mass balance of an isolated system.
Finite
True or False? : Isolated systems exist.
False - Isolated systems are 100% theoretical and do not exist.
What is a closed system in systems theory?
A system with inputs and outputs of energy, but no inputs and outputs of mass.
What type of system do cycles tend to be?
Closed systems - here the finite balance of mass is recycled around the system in various forms.
What type of system is the Earth?
A closed system.
Why is the Earth classed as a closed system?
There is a negligible input and output of mass, which has virtually no effect on the planet’s overall mass balance.
What input to the Earth is virtually so small it has a negligible effect on the planet’s overall mass balance, hence the planet is classed as a closed system?
Meteorites
What output from the Earth is virtually so small it has a negligible effect on the planet’s overall mass balance, hence the planet is classed as a closed system?
Spacecraft (they also tend to return) and satellites.
What is an open system in systems theory?
A system with an input and output of both energy and matter.
Describe the mass balance of an open system.
Variable. It depends on the magnitude of inputs and outputs.
What is dynamic equilibrium in systems theory?
When the inputs entering the system are equal to the outputs leaving, thus there is no overall change in the energy or mass balance.
What is a feedback mechanism in systems theory?
Mechanisms employed to either increase or decrease the effect external change has on the dynamic equilibrium of a system.
What is a positive feedback mechanism in systems theory?
A response which amplifies the change in the equilibrium of the system, meaning that the system moves even further away from its previous state.
What is a negative feedback mechanism in systems theory?
A response which attempts to maintain the equilibrium of the system by counteracting the changes in inputs or outputs. It tries to bring the system back closer ti its previous state.
What are the 3 states that water may exist in?
Solid, liquid or gas.
What determines the state of water?
The energy it possesses.
What is the name for water in a solid state of matter?
Ice
What is the name for water in a liquid state of matter?
‘Water’
What is the name for water in a gaseous state of matter?
Water vapour
What is the process in which water changes from a solid to a liquid?
Ablation
What is the process in which water changes from a liquid to a solid?
Freezing
What is the process in which water changes from a liquid to a gas?
Evaporation
What is the process in which water changes from a gas to a liquid?
Condensation
What is the process in which water changes from a solid to a gas without becoming a liquid?
Sublimation
What is the process in which water changes from a gas to a solid without becoming a liquid?
Deposition
What is another term for deposition?
Desublimation
How old is the Earth?
4.5 billion years old
How did water end up on the Earth?
It was deposited on the planet by comets.
How much water is on the planet Earth?
1,386 million km3
What are the 2 types of water?
Saltwater and freshwater
What distinguishes between saltwater and freshwater?
Saltwater contains dissolved salts, freshwater does not.
What percentage of the Earth’s water is saltwater?
97.5%
What percentage of saltwater is stored in the oceans?
96.9%
What percentage of the planet is covered by the oceans?
2/3
What percentage of the water on the Earth is freshwater?
2.5%
What percentage of freshwater is located in the cryosphere?
68.7%
What are the 5 main cryospheric stores?
- Glaciers
- Ice sheets
- Ice caps
- Sea ice
- Permafrost
Where are the cryospheric stores located?
The high altitudes and the high latitudes.
What percentage of freshwater is stored as groundwater?
30.1%
What percentage of freshwater is stored in lakes?
0.26%
What percentage of freshwater is stored in rivers?
0.06%
What percentage of freshwater is stored in wetlands?
0.03%
What percentage of freshwater is stored as soil moisture?
0.05%
What percentage of freshwater is stored in the atmosphere?
0.04%
The water in the atmosphere could cause how many days’ worth of continual rain?
10 days
What percentage of freshwater is stored in the biosphere?
0.03%
What is residence time?
The average time mass spends in a store.
What is the residence time of soil?
1-2 months
What is the residence time of channel discharge?
2-6 months
What is the residence time of seasonal snow cover?
2-6 months
What is the residence time of glaciers?
20-100 years
What is the residence time of lakes?
50-100 years
What is the residence time of groundwater?
Up to 10,000 years.
What is the magnitude of a store?
The quantity of mass it contains.
What are the 2 processes which determine short-term changes in cryospheric storage?
Accumulation and ablation
What is accumulation?
The build-up of snow and ice in the cryosphere. An input into cyrospheric systems.
What is ablation?
The melting of snow and ice. An output from cryospheric systems.
What causes seasonal/short-term variations in cryospheric storage?
Temperature.
What are the 2 causes of long-term changes in cryospheric storage?
- The Milankovitch cycles
2. Plate tectonic movements
What are the Milakovitch cycles?
3 long-term natural processes which affect the orbit of the Earth around the Sun, bringing warming and cooling periods as they change the levels of insolation we receive.
How many Milankovitch cycles are there?
3
What are the 3 Milankotvich cycles?
- Change in orbit
- Change in tilt
- Wobbling of the axis
What is the 1st Milankovitch cycle and what does it do?
Change in orbit - every 100,000 years the orbit of the Earth changes from spherical to elliptical.
What is the 2nd Milankovitch cycle and what does it do?
Change in tilt - The Earth’s axis is currently titled at 23.5 degrees. Every 41,000 years, this changes between 22 and 24.5 degrees..
What is the 3rd Milankovitch cycle and what does it do?
Wobbling of the axis - every 22,000 years the axis wobbles.
How does plate tectonic movement affect long-term changes in cryospheric storage?
It moves the continents to other climatic zones.
How many planetary spheres are there?
5
What are the 5 planetary spheres?
- Lithosphere
- Hydrosphere
- Biosphere
- Cryosphere
- Atmosphere
What is the lithosphere?
The rocks and soil of the Earth.
What is an alternative name for the lithosphere?
The geosphere.
What types of hydrological stores are found in the lithosphere?
Groundwater and soil moisture.
What are the alternative names for the planetary spheres of the Earth?
The planetary domains or planetary sub-systems.
What is the hydrosphere?
All of the liquid water on the surface of the Earth.
What types of hydrological stores are found in the hydrosphere?
Oceans, seas, lakes and rivers.
What is the biosphere?
All of the life on Earth: flora and fauna.
What types of hydrological stores are found in the biosphere?
All of the water found in organisms.
What is the cryosphere?
All of the ice on Earth.
What types of hydrological stores are found in the cryosphere?
Glaciers, ice caps, ice sheets, sea ice and permafrost.
What is the atmosphere?
The layer of gases surrounding the planet Earth.
What types of hydrological stores are found in the atmosphere?
Water vapour, including clouds.
What is a drainage basin?
An area of land drained by a river and its tributaries.
What is the alternative name for a drainage basin?
A river’s catchment.
What is the name of the boundary of the drainage basin?
The watershed.
What is the watershed and how is it identified?
The boundary of the drainage basin, marked by a ridge of high land, beyond which any precipitation which falls shall drain into the adjacent basin.
What is the drainage basin hydrological cycle?
The water cycle on a smaller scale taking place within the system of the drainage basin.
What type of system is the drainage basin hydrological cycle?
An open system.
What is the input into the drainage basin hydrological cycle?
Precipitation.
What forms can precipitation take?
- Rain
- Snow
- Hail
- Frost
- Sleet
- Dew
What are the 4 characteristics of precipitation which determine how a drainage basin responds to it as an input into the drainage basin hydrological cycle?
- Type
- Amount
- Duration
- Intensity
FILL IN THE GAP: As a general rule, the higher the intensity of rainfall, the _______ the duration?
A. Longer
B. Shorter
B. The higher the intensity, the shorter the duration.
What is the energy input into the drainage basin hydrological cycle?
Insolation from the Sun.
What is interception?
When precipitation is stopped from directly reaching the surface of the Earth by vegetation.
What store follows the flow of interception?
Interception storage.
What is throughfall?
When water in interception storage drops to the surface of the Earth from leaves.
What is stemflow?
When water in interception storage reaches the surface of the Earth by flowing down the trunk or stem of the plant.
What is infiltration?
The vertical movement of water from the surface of the Earth into the soil.
What is rate of infiltration?
The rate at which water passes into the soil through infiltration.
What is an alternative term for infiltration rate?
Infiltration capacity.
What is the unit of measurement for infiltration rate?
Millimetres per hour (mm/h)
How does surface storage accumulate?
When the infiltration rate exceeds the rate at which water reaches the ground.
What is capillary action?
The drawing up of water from the soil during drier periods.
What is overland flow?
The movement of water over the surface of the land towards a body of water.
What is the alternative name for overland flow?
Surface run-off
What are the 2 types of overland flow?
- Saturation-excess
2. Infiltration-excess
What is saturation-excess overland flow?
Overland flow which occurs when the soil has became saturated due to long-duration rainfall.
True or False? : Saturation-excess overland flow will only develop if there is a slope to the land.
True - Otherwise, the surface storage will develop into a salt marsh.
On a slope, which are becomes saturated first?
The bottom of the slope.
What is a saturation wedge?
On a piece of sloped land, the land near the bottom of the slope becomes saturated first and this gradually ascends up the slope.
What is infiltration-excess overland flow?
Overland flow which develops due to high intensity rainfall when the infiltration rate is overcome by the rate at which water reaches the ground.
In which part of the world is infiltration-excess overland flow common?
Semi-arid areas.
What can happen when infiltration-excess overland flow develops in semi-arid areas?
Flash flooding and the growth of large, deep channels called wadis which fill with water when it rains.
What is throughflow?
The lateral movement of water through the soil from soil moisture storage to channel storage.
How is water able to flow laterally through the soil in throughflow?
- Via a matrix of pores and fissures.
2. Via pipes.
What are pipes?
Wide gaps in the soil created by roots and animal burrows.
What is pipeflow?
The lateral movement of water through pipes in the soil. A type of throughflow.
What is faster, and why? Throughflow through a matrix of pores and fissures, or pipeflow?
Pipeflow.
In which region of the soil is throughflow most effective and why?
The surface horizons as the weight of overlying is less compactive on the soil.
What is permeability?
The ease at which water can pass through rocks or soil.
What is percolation?
The vertical movement of water from soil moisture storage to groundwater storage, passing from the soil to underlying bedrock.
What happens to permeability as water percolates?
It decreases and slows down percolation, causing water to pool.
What is groundwater flow?
The lateral movement of water through the bedrock.
What is the slowest flow in the drainage basin hydrological cycle?
Groundwater flow
What is the mechanism which allows groundwater flow to take place?
The porosity of rocks.
What is the alternative term for groundwater flow?
Baseflow
What is porosity?
The measure of the void spaces in a material, given as a percentage of the total volume.
What type of rock has a high porosity?
Coarse-grained sedimentary rocks.
What type of rock has a low porosity?
High-grained igneous rock.
What is channel flow?
The flow of water in the river channel.
What is the alternative term for channel flow?
River discharge
What is interception storage?
The capture of precipitation by vegetation as it intercepts it from reaching the surface of the Earth.
Where does interception storage take place?
On the surface of plants and their leaves.
Is interception storage a permanent store?
No, it is a temporary store with a low residence time.
Why does water in interception storage have a low residence time?
Water may swiftly leave via evaporation, or through throughfall or stemflow if the magnitude of the store is overcome.
Why is there spatial variation in interception storage in the drainage basin?
Land use and vegetation type varies.
What causes seasonal variation in interception storage?
In autumn plants shed their leaves.
What happens to the amount of precipitation reaching the surface of the Earth as intensity increases?
It also increases as interception storage can be overcome.
What is vegetation storage?
Water stored in biomass.
How does water enter vegetation storage?
It is absorbed by its roots from soil moisture storage.
What is the alternative term for vegetation storage?
‘Green water’
What is surface storage?
The water stored on the surface of the Earth.
What is depression surface storage?
Surface storage in depressions and hollows on the surface of the Earth.
What type of store is fallen snow?
Surface storage.
Give examples of surface storage.
Puddles, ponds, lakes and reservoirs.
What are the 4 situations under which surface storage will develop?
- Saturated soil (long-duration rainfall)
- Infiltration rate overwhelmed (high-intensity rainfall)
- Hard, dry soil following dry period
- Impermeable materials in urban areas
What is pluvial flooding?
Flooding in urban areas caused by impermeable materials.
What is soil moisture storage?
The water stored between soil particles.
What is soil?
The collection of unconsolidated particles of irregular shapes and sizes which makes up the surface of the Earth.
What is a pore?
The bois space between soil particles.
What are the 3 types of soil moisture?
- Gravitational water
- Capillary water
- Hygroscopic water
What is gravitational water?
The excess water which occupies the large, free-draining spaces in the soil.
What happens to gravitational water after a rainfall event?
It drains away.
What would happen if gravitational water were to remain after a rainfall event?
The soil would become waterlogged and unable to support precipitation.
What is capillary water?
The water in thick films which occupies the small pore spaces in the soil.
What holds capillary water in place?
Surface tension
What happens to capillary water after a rainfall event?
It remains in the soil where it is used by plants.
Which type of soil moisture is essential for plant life?
Capillary water.
What is hygroscopic water?
Water adhering to the hydrophilic coatings of soil molecules.
True or False? : Hygroscopic water is available for plants.
False - Hence it is relatively insignificant.
What are the 3 different states of soil moisture storage?
- Saturation
- Field capacity
- Wilting point
What is saturation?
Where the soil is completely full of water. There are no spaces of air at all. The water table rests near the surface horizons.
What is field capacity?
The total amount of water remaining in the soil after all the gravitational water has drained away. There are some spaces for air.
What is wilting point?
Where there is insufficient water in the soil to compensate for any plant and water losses from transpiration. There are many spaces of air in the soil.
What is groundwater storage?
The water stored in the bedrock.
How does groundwater storage form?
Percolating water slows down and accumulated as the permeability of the geology decreases. It sits above an impermeable layer of bedrock.
What is the water table?
The upper surface of groundwater storage.
What is channel storage?
Water stored in the river channel itself.
What is channel precipitation?
Precipitation that falls directly into the river channel.
What are the 3 flows which lead to channel storage?
Overland flow, throughflow and groundwater flow.
What are the 3 outputs in the drainage basin hydrological cycle?
- Evaporation
- Transpiration
- Channel discharge
What is evaporation?
When water changes state from a liquid to a gas as it is given more energy.
In which stores can evaporation occur?
All - but mainly those above the surface of the Earth.
What affects evaporation?
Meteorological factors such as temperature, humidity, wind speed and hours of sunshine.
What is transpiration?
The biological process in which water diffuses from vegetation storage into the atmosphere through the stomata?
What are stomata?
Pores on the underside of a plant leaf.
Generally, how does surface area affect a plant’s ability to transpire?
It increases it as there are more stomata.
What affects transpiration?
Climatic factors such as temperature and humidity.
What is evapotranspiration?
The combined water loss to the atmosphere from both evaporation and transpiration.
What is potential evapotranspiration?
The potential amount of water that could be lost through evapotranspiration.
What is actual evapotranspiration?
The amount of water actually lost through evapotranspiration.
What is channel discharge as an output in the drainage basin hydrological cycle?
The volume of water lost to the sea as it flows from rivers
What is river discharge?
The volume of water flowing through a point on the river’s course at any point in time.
What is the measurement for river discharge?
Cumecs (cubic metres per second)
What is a river regime?
A description of the annual variations in river discharge at a point on the course. It may be plotted as a graph.
What is a simple river regime?
A regime with only one peak discharge.
What is a complex river regime?
A regime with more than one peak discharge.
What physical factors affect a river’s regime (7)?
- Annual precipitation patterns
- Temperature
- Evaporation
- Relief
- Geology
- Vegetation
- Snowmelt
What human factors affect a river’s regime?
- Engineering
2. Irrigation
Where is the Colorado River?
South-west USA and northern Mexico.
How long is the Colorado River?
1,450 miles long.
Where is the source of the Colorado River?
The Rocky Mountains
Which famous landmark does the Colorado River flow through?
The Grand Canyon Arizona.
Where is the mouth of the Colorado River?
The Gulf of California in Mexico
What percentage of the USA is drained by the Colorado River?
7%
In proportion to the size of France, how large is the drainage basin of the Colorado River?
1.1 times the size of France
How many US states does the Colorado River drainage basin cover?
7 (Wyoming, Colorado, Utah, Nevada, Arizona, New Mexico, California)
How many Mexican states does the Colorado River drainage basin cover?
2 - Sonora and Baka California
What is the weather like in the Colorado River drainage basin?
Arid with daytime temperatures above 40 degrees, and a low humidity.
Which mountains lie to the west of the Colorado River?
The Sierra Nevada mountains
What is the effect of the Sierra Nevada mountains on the Colorado River drainage basin?
They create a rain shadow effect.
What is the average annual precipitation for some areas of the Colorado River’s drainage basin?
25mn a year
What percentage of rainfall that falls in the Colorado River drainage basin evaporates?
95%
How many Americans rely on the Colorado River for water?
Over 40 million
How many Californians rely on the Colorado River for water?
25 million
Between 2000 and 2006, the population of the Colorado drainage basin grew by how many people?
5 million
What large settlements lie in the Colorado River’s drainage basin?
Las Vegas, Los Angeles, San Diego, Phoenix, Tuscon and San Bernardino.
How many HEP dams sit on the Colorado River?
11
How many hectares of farmland are irrigated by the Colorado?
1.4 million hectares
What feeds the Colorado River?
Snowmelt from mountains
What type of river regime does the Colorado naturally have?
A complex one with several peaks and troughs over the course of the year.
What is meant by the Colorado having a naturally bi-seasonal regime?
It has 2 marked periods of peaks.
Naturally when is the largest peak in the Colorado’s discharge?
Mid-summer when she snowpacks melt.
In the early 20th century, the discharge of the Colorado River was how many times higher in the summer than it was in the winter?
13
Naturally in the Colorado’s regime, what do individual peaks correspond with?
Snowmelt arriving from a different tributary river somewhere within the huge drainage basin, because mountain snowpacks melt at different times.
When was the 2nd peak discharge in the Colorado’s natural regime?
October.
Why was the 2nd peak of the Colorado’s natural regime in October?
Violent conventional rainstorms in the autumn.
Which peak in the Colorado’s discharge lasted longer? The mid-summer peak or the October peak?
The mid-summer peak.
What was done to manage the regime of the Colorado River?
Dams were built along its course.
Where is the Glen Canyon dam?
Arizona
In what year was the Glen Canyon dam constructed?
1966
Where is the Hoover Dam?
On the border between Arizona and Nevada.
In what year was the Hoover Dam constructed?
1935
Which lake does the Hoover Dam create?
Lake Mead
How much discharge is found in Lake Mead?
2 years’ worth
What type of regime does the Colorado River have now?
A simple regime.
When is the discharge of the Colorado River at its peak now?
Mid-March
What has been the effect of engineering strategies on the Colorado River on water clarity?
Water has became clearer as dams act as a sediment trap.
What has been the effect of engineering strategies on the Colorado River on sandbanks?
Sandbanks have reduced in size or disappeared as they have been starved of sediment.
What has been the effect of engineering strategies on the Colorado River on water temperature?
Water has become colder as a result of the reduction in sediment load due to the specific heat capacity of the load meaning it previously warmed up quicker.
What has been the effect of engineering strategies on the Colorado River on wildlife?
Species have been lost due to changes in the river’s load, temperature and sandbanks. However, the trout population has grown as they prefer cooler, clearer water.
How many species of fish have been lost in the Colorado River?
4 - including the squawfish.
Why have species of fish been lost in the Colorado River?
These fish thrived in warm, silty waters.
What species have declined in numbers due to the loss of the Colorado sandbanks?
The Kanab snail and willow flycatcher.
What has been the effect of engineering strategies on the Colorado River on recreational activities?
People can no longer use the sandbanks for fishing or rafting.
What is the formula for river discharge?
Cross sectional area X velocity
What is a storm hydrograph?
A graph which shows the discharge of a river during a rainfall event.
What does a strom hydrograph reveal?
A river’s response to a rainfall event.
