Water and Carbon Cycles Flashcards
What is an input?
Addition of matter into and/or energy into a system.
What is a process?
A sequence of actions that can influence the movement of energy and/or matter.
What is an output?
Removal of matter and/or energy out of a system.
What is a system?
A system comprises any set of inter-related components that are connected together to form a working unit.
What is a system an assemblage of?
Stores and flows
What are elements in terms of a system?
The key parts of the system.
What are attributes in terms of a system?
Key characteristics of the elements.
What are relationships in terms of a system?
How the different elements work together to form a process.
What are all systems held within, and what are they?
Boundaries and these are generalisations of reality with minor details removed.
How do systems function?
By having inputs and outputs of material that is processed along the way.
Material flows from one component to another.
What are the three types of system?
Isolated
Closed
Open
What is an isolated system?
No interactions with anything outisde the system boundary.
These are rare.
What is a closed system?
Energy is transferred into and out of the system.
All matter is enclosed.
Examples would be the global water and carbon cycle.
What is an open system?
Matter and energy can be transferred from the system into the surrounding environment.
For example the drainage basin (water) or a woodland (carbon).
What is feedback?
When inputs or outputs suddenly change, the stores are forced to change and the equilibrium is upset.
What is positive feedback?
Occurs where the effects of an action are amplified by changes to the inputs/outputs/processes.
What is negative feedback?
Occurs where the effects of an action are nullified by changes to the inputs/outputs/processes.
What type of system is the Earth and why?
Closed
Energy comes in as solar energy, balanced out by the radiant energy lost by the Earth.
What are the five subsystems on Earth?
Atmosphere- air
Lithosphere- geology
Hydrosphere- water
Biosphere- organic life
Cryosphere- ice
Do the five subsystems work together?
Each of the 5 subsystems work as an open system with interlocking relationships, known as a cascading system.
These interlocking relationships have a profound effect on the Earth’s climate.
How much of the Earth’s water is saline?
97%
What are the two main freshwater stores on Earth?
Ice sheets (Antractica and Greenland) and groundwater.
Name three stores which have a suprisingly small amount of water?
Rivers, lakes and the atmosphere.
How is water transfered between the atmosphere to the Earth’s surface?
Precipitation
How is water transfered from the Earth’s surface to the atmosphere?
Evaporation and transpiration
How is water transfered to underground stores?
Infiltration and percolation
How much of the Earth’s saline water is in oceans?
Approximately 96.5%
How much water is there estimated to be on Earth?
1.338 billion km3.
If 97% of the earth’s water is stores as oceanic water where is the other 3% stored?
As land ice, glaciers and permafrost (cryospheric water)
As groundwater, lakes, soil, wetland, rivers and biomass (terrestrial water)
As vapour and liquid droplets in the atmosphere (atmospheric water)
How much of all freshwater is stored in rocks deep below the ground?
30.1%
What is an aquifer?
A body of porous rock or sediment saturated with groundwater.
Where are aquifers commonly found?
In porous (contain air pockets) and permeable (allow water through) rocks such as sandstone and chalk.
Where are most of the world’s underground stores of freshwater found?
Northern and Eastern Europe
Throughout Indonesia and eastern Australia
Northern and central Africa
Throughout South America
How are aquifers formed?
Water enters the rocks either directly or very slowly through overlying soil.
Soils vary massively in their ability to store and transfer water- this is the soil moisture budget.
Porous sandy soils store little but transfer vast amounts of water.
Clay soils store huge amounts of water, but allow very little to transfer through.
What is the upper level of saturated rock called?
The water table.
Does the water table need to be managed at the same level, in a state of equilibrium?
Yes, through careful management.
Why does the water table rise or fall?
In response to groundwater flow, water abstraction by people or by recharge (additional water flowing into the rock).
What are fossil aquifiers?
Aquifiers found in the deserts of Africa, Australia and the Middle East.
These were formed thousands of years ago when the climate in these regions was much wetter.
How may fossil aquifiers be exploited?
If they are used unsustainably for irrigation as this increases the risk of them turning into saline aquifiers.
This is because seawater can then infiltrate into the rocks.
Over what time scales can water in stores change?
Daily to geological (1000s of years).
How much water (as vapour) does the atmosphere contain?
12,900 km3
Is vapour a greenhouse gas?
Yes, and so any changes can be a direct cause of climate change.
How much of the Earth’s total water is in the atmosphere?
0.4%
What states does atmospheric water exist in and which is the most prevalent?
Solid- ice
Liquid- water
Gas- water vapour, which is the most prevalent.
Why is atmospheric water vapour so important?
It absorbs, reflects and scatters incoming solar radiation- this keeps the atmosphere at a temperature that can maintain life.
How can temperature influence the amount of water vapour the air can hold?
Cold air cannot hold as much water vapour as warm air, which results in air over the poles being quite dry, whereas air over the tropics is very humid.
Relationship between an increase in water vapour and atmospheric temperature.
An increase in water vapour (even small) will lead to an increase in atmospheric temperature.
Why is the relationship between increase in water vapour and atmospheric temperature a positive feedback loop?
A small increase in global temperature would lead to a rise in global water vapour levels, thus further enhancing the atmospheric warming.
What are clouds?
A visible mass of water droplets or ice crystals suspended in the atmosphere.
How are clouds formed?
Cloud formation is the result of air in the lower atmosphere becoming saturated due to:
- Cooling of the air, leading to condensation
- Adding of extra water vapour
When do cloud droplets fall as rain?
When the cloud droplets grow large enough.
What is the average water depth of oceans?
3.68 km
How many oceans are there?
7
How many seas are there?
130
How much of the Earth’s surface is covered in water?
72%
Why can oceanic water stay liquid at temperatures below 0 degrees?
As it contains dissolved salts
Are oceans alkaline or acidic?
Alkaline but have become more acidic over time
What is the current pH of oceans?
8.14
What did the pH of oceans used to be 250 years ago?
8.25
Why have oceans become more acidic?
Increased absoption of carbon from the atmosphere as this forms carbonic acid.
What is the cryosphere?
Areas where water is in a solid form, for example ice.
Name 5 locations of the cryosphere.
Sea ice- e.g. Arctic Ocean
Permafrost (permanently frozen ground)- e.g. Siberia
Ice caps- e.g. Iceland
Ice sheets- e.g. Greenland
Alpine glaciers- e.g. The Alps
When does sea ice form?
When water in the oceans is cooled well below freezing.
Name an example of sea ice forming.
The freezing of the Arctic Ocean every winter.
What is an ice sheet?
A mass of glacial ice that is greater than 50,000 km2 in area.
Where are the two ice sheets in the world?
Antarctica and Greenland
Where did ice sheets use to cover in the last ice age?
North America, northern Europe and Argentina
Between Greenland and the Antarctica, how much of the Earth’s freshwater ice is there?
99%
How big is the Antarctic ice sheet?
14 million km2
How big is the Greenland ice sheet?
1.7 million km2
Where are ice sheets found and why?
In high latitudes where summer temperatures are not warm enough to melt winter snowfall.
As such, layers of snow piled up over thousands of years, compressing older snow layers into ice.
Are ice sheets constantly in motion?
Yes, slowly flowing downhill under their own weight.
Where do ice sheets move faster?
At the coast, they move through faster moving outlets such as ice streams, glaciers and ice shelves.
What does icebergs breaking off ice sheets cause?
Temporary sea level rise as they enter the ocean (due to displacement) but they then melt in the water itself.
Why would ice sheets melting be catastrophic?
They contain enormous quantities of frozen water.
If the Greenland ice sheet melted how much would sea level rise by?
6m
If the Antarctic ice sheet melted, how much would sea level rise by?
60m
What are ice caps?
Thick layers of land-based ice that are smaller than 50000 km2.
Where are ice caps usually found?
In mountainous areas, and they tend to have a dome-shaped centre at the highest point.
Where do ice caps flow?
They flow outwards, covering everything in their path and feeding ice into several surrounding valley glaciers.
Where do ice caps occur?
All over the world, from polar to mountainous regions for example The Himalayas.
Where is Africa’s only remaining ice cap and what is it called?
The Furtwangler glacier
Found on the summit of Mt Kilamanjaro
Due to climate change, how much of the Furtwangler’s ice melted between 1912 and 2011?
85%
When is the Furtwangler estimated to disappear by?
2040
What are alpine glaciers?
Thick masses of ice found in deep valleys and upland hollows.
They are usually fed by ice caps or small corrie glaciers.
How many valley glaciers are in the Himalayas and where do they provide water supply to?
15,000 valley glaciers which supply water to several rivers, for example Indus, Ganges and Brahmaputra.
These rivers are the lifeline for millions of people in South Asian countries such as India and Bangladesh.
What is permafrost?
Ground (soil or rock) that remains frozen for at least two consecutive years.
What do depths of permafrost vary from?
1 to 1500 metres.
When was most of the permafrost existing today formed?
During the last ice age (110000 to 12000 years ago), having also survived the recent warm period known as the Holocene.
Where is permafrost found in the Antarctic?
Beneath both glaciated and ice-free regions.
It is also found along the Antarctic coastline underneath near-frozen seas.
When was the permafrost along the Antarctic coastline formed?
When sea levels were much lower, and they have been preserved ever since by the cold ocean waters above.
What happens when permafrost melts?
Permafrost has been melting due to global climate warming.
This is releasing large amounts of trapped methane, which in turn contributes further to the greenhouse effect.
What four categories can terrestrial water fall into?
Surface water
Ground water
Soil water
Biological water
What is surface water?
The free-flowing water of rivers, as well as the surface water stores of ponds and lakes.
What are rivers?
Streams of water within a defined channel, they act as both a store and transfer of water.
How are rivers transfers and stores?
Rivers transfer water from the ground, soils and the atmosphere to a store such as wetlands, lakes or oceans.
Rivers make up what percentage of all water?
0.0002%
What is the world’s largest river and how much of the world’s total river flow does it account for?
The Amazon and it accounts for 1/5 of the world’s river flow.
The Amazon drains an area of how much?
7,050,000 km2
What is the discharge of the Amazon?
209,000m3 per second into the Atlantic Ocean- this is more than the next 7 largest rivers combined.
What are lakes?
Stores of fresh water found in hollows on the land surface larger than two hectares in area.
Anything smaller is deemed to be a pond.
Where are the majority of lakes?
In the Northern Hemisphere at higher latitudes
How many lakes does Canada have?
At least 2 million.
How many large lakes does Finland have?
56,000 (greater than 10,000 m2)
What is the world’s largest lake and it’s size?
Caspian Sea
78,200km2
What is the Caspian Sea?
A lake which is a remnant of an ancient ocean and is about 5.5 million years old.
It is generally fresh water, though becomes more saline in the south where there a fewer rivers flowing into it.
What is the world’s deepest lake and how deep is it?
Lake Baikal in Siberia, which reaches depths of 1637m.
What are wetlands?
Areas of marsh, fen, peatland or water, which can be natural or artificial, permanent or temporary and static or flowing.
Importantly, there is a dominance of vegetation.
Wetlands can be areas where…
Water covers the soil
Water is present at or near the surface of the soil all year round
Water is present for varying periods of time during the year, including during the growing season.
What animal species can be found in wetlands?
Aquatic and terrestrial animal species.
Why do plants need to be adapted to survive in wetlands?
There is a prolonged presence of water.
Furthermore, unique wetland soils are created.
Name seven reasons why wetlands widely vary.
Soils
Topography
Climate
Hydrology
Water chemistry
Vegetation
Human disturbance
Where are wetlands found?
At all latitudes on all continents except Antarctica.
What is the main ecosystem in the Arctic?
Wetlands.
The peatlands, rivers, lakes and shallow bays cover 60% of the total surface area.
What do Arctic wetlands do?
Store enormous amounts of greenhouse gases and provide habitats for a wide range of Arctic species.
What and where is the Pantanal?
The Pantanal is the world’s largest freshwater wetland system, it is a complex system of marshlands, floodplains, lagoons and interconnected drainage lines.
It extends through central-western Brazil, eastern Bolivia and eastern Paraguay.
Name three functions of the Pantanal for locals.
Transport
Water supply
Flood prevention
What is ground water?
Water that collects underground in the pore spaces of rock up to an agreed depth of 4km.
Name an example of groundwater extending to depth further than 4km.
A borehole in the Kola Peninsula in northern Russia found huge quantities of hot mineralised water at a depth of 13km.
What is the water table?
The depth at which rock becomes completely saturated with water.
What can lead to the formation of oases and wetlands?
When groundwater eventually emerges at the surface at springs.
Why is the amount of groundwater available reducing rapidly?
Extensive extraction for use in irrigating agricultural land in dry areas.
What is soil water?
Water which is held, together with air, in the unsaturated upper layers of soil.
What can soil water affect?
Weather and climate
Surface runoff
Soil erosion
Slope failure
Resevoir levels
Water quality
What is soil moisture important for?
Controlling the exchange of water and heat between the land surface and atmosphere through evapotranspiration.
It plays an important role in the development of weather patterns and production of precipitation.
What is biological water?
Water stores in plants (biomass).
Do animals have much of an impact on biological water?
No as they store relatively little water.
What does biological water depend on?
Vegetation cover and type (e.g. areas of dense rainforest store much more water than desert plants).
What is the process of transfer and storage of water in a plant?
Plants/trees take in water through their roots. This is transported to and stored in the trunk/branches.
Water is lost by transpiration through the stomata on the underside of leaves.
This process through plants helps to regulate the climate in specific environments.
What are some adaptations of cacti?
They gather water from deep underground via their taproots and then store it for a long time in their succulent trunk.
Minimal water loss from tiny needles.
What are some adaptations of the baobab tree?
Can store vast amounts of water in its trunk, although this is mainly for strength rather than for tree growth.
How can climate become more desert-like relating to biological water?
If vegetation is destroyed (for example by deforestation), the store is forever lost to the atmosphere, preventing the recycling of water and causing the climate to become more desert-like.
What is the residence time of soil moisture?
1-2 months.
What is the residence time of rivers?
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 shallow groundwater?
100-200 years.
What is the residence time of deep groundwater?
10,000 years.
Why may water not remain in soil long?
It may be quickly percolated into bedrock.
It may be transpired by plants into the atmosphere.
It may be transferred into rivers by throughflow.
It may be evaporated into the atmosphere.
Name three example of water stores changing in size over time.
- The freezing and melting of the Arctic sea ice every winter/summer.
- The passage of weather fronts and/or storms which bring deluges of atmospheric rain.
- The growth and retreat of glaciers in-between ice ages.
What three states does water exist in on Earth?
Liquid water
Gaseous water vapour
Soild ice
What is either absorbed or released when water changes state?
Energy in the form of latent heat.
What is energy in the form of latent heat important for?
Atmospheric processes, such as cloud/precipitation formation.
When does evaporation occur?
When heat energy from solar radiation is transferred to surface water, encouraging liquid water to change state into gaseous water vapour.
What is evaporation affected by?
The amount of solar energy available
The availability of water
The humidity of the air (higher humidity=less evaporation)
Air temperature (warmer air can hold more vapour = more evaporation).
How do all terrestrial plants lose water?
Transpiration.
What is transpiration?
Where water is transported from the roots of a plant to its leaves and lost through stomata on the underside of the leaves.
What three conditions can increase transpiration?
Hot
Dry
Windy
How does water evaporating cool its surroundings?
By using energy (latent heat).
Can leaves intercept rain?
Yes
When will air reach saturation (dew point)?
When air is cooled sufficiently as it will be able to hold less vapour.
What happens at saturation?
Excess water in the air is then converted back into liquid water.
What two things do vapour molucules need either of to condense?
Small particles to condense on (e.g. smoke, salt, dist). These are known as condensation nuclei.
Surfaces that are colder than the dew point temperature (e.g. leaves, grass, windows). If colder than freezing point, then the vapur sublimates to form hoar frost.
What is condensation?
The direct course of all forms of precipitation.
When does condensation occur?
- When temperature of the air is reduced to dew point- this occurs when warm moist air passes over a cold surface. Also, on a clear winter’s night when heat is radiated out to space when the ground gets colder, cooling the air directly in contact with it.
- When the volume of air increases but there is not addition of heat. This happens when air rises and expands in the lower pressure of the upper atmosphere, when either (relief or frontal rain occurs).
What is relief rainfall?
When moist air is forced to rise over mountains.
What is frontal rainfall?
Masses of air of different temperatures meet- the less dense warm air rises over the cooler air.
Why is cloud formation not evenly distributed across the Earth’s surface?
Global atmospheric circulation.
What creates spatial and temporal changes in water stores in equatorial regions?
The ITCZ moving north/south.
What happens in the ITCZ?
At the equator, high temperatures result in high rates of evaporation. The warm moist air rises, cools and condenses to form towering banks of cloud and heavy rainfall in the ITCZ.
What is the ITCZ?
The Inter-Tropical Convergence Zone is a low pressure zone near the equator.
In the mid latitudes, what drives cloud formation?
The convergence of warm Tropical air and cold Arctic air.
The boundary of these two air masses creates the Polar Front- resulting in rising air and cloud formation.
What causes largely changeable weather conditions like those experienced in the UK?
Strong upper level winds in the Jet Stream drive unstable weather systems across the mid latitiudes.
Can cloud formation occur on a localised scale?
Yes, for example convectional thunderstorms.
However, this is very ‘hit and miss’ but does demonstrate that variarions in water cycle processes can occur at the local scale.
What is fog and when does it form?
A visable aggregate of minute water droplets suspended in the atmosphere near the Earth’s surface.
In cold environments/temperatures.
How is glacial ice formed?
When snow falls on glaciers and ice sheets it becomes compressed and will enter long terms store as layers of glacial ice.
Are Earth’s ice stores stable?
No, they are not over geological time.
Describe the seasonal variation of the mass of glaciers.
Snow accumulated during the winter adds to the mass of a glacier or ice sheet.
In the Summer, melting occurs and ice calves (breaks away). Meltwater evaporates and even ice directly produces steam (this is known as sublimation).
What is the equilibrium line?
The altitude where annual accumulation and melting are equal.
In recent decades has the equilibrium line risen to higher altitudes?
Yes- most glaciers in the world are now shrinking and retreating.
At the peak of the last ice age, how much of the world was covered by glaciers and ice sheets?
1/3
In the last ice age, how much lower were sea levels?
100m- as water was locked up as snow and ice
What is an impact the melting of freshwater ice could have?
The melting of the Antarctic and Greenland ice sheets could result in a catastrophic 60m rise in sea levels.
Describe the impact of climate change in terms of a poitive feedback loop.
Rising seas would destabilise ice shelves, triggering calving and further melting.
During warmer period in the past how much higher were sea levels than today’s and why?
50m due to a decline in the amount of water stores as snow and ice.
What are five processes which can affect the water cycle on a local scale?
Deforstation
Storms
Urbanisation
Seasonal changes
Farming.
What is the size of water stores within the hillside water cycle affected by?
Human and physical factors occuring over a short time period (e.g. an intense rainstorm over an urban area).
What is the most influential water transfer in the hillslope water cycle?
Infiltration
What could happen to water trapped on the ground surface in the hillslope water cycle?
Stored as surface storage
Evaporate
Flow downslope as overland flow- this will often lead to flooding.
What is the impact of deforestation of local water stores?
More water enters local water stores as there is less interception and so there is a faster lag time.
What is the impact of storms on local water stores?
Increases the volume of water in water stores are ground will become saturated, decreasing the lag time and increasing the flood risk.
What is the impact of farming on local water stores?
Decreases the lag time as water gets to stores faster due to the compression of soils and the amount of ground water due to irrigation.
Ditches can drain the land and encourage water to flow quickly to rivers.
What is the impact of seasonal changes on local water stores?
Freezing water before it reaches lakes or other stores can reduce the volume of water in store.
Cryospheric melting can increase the flood risk.
What is the impact of urbanisation on local water stores?
Impermeable surfaces reduce infiltration.
Trees are likely to be cur down reducing interception.
Urbanisation will decrease the lag time, increasing the flood risk.
What is the soil moisture budget?
A graph of how key inputs/outputs of water within a drainage basin change over the course of a year.
These are monthly precipitation.
What equation is used to work out the water budget for a drainage basin?
Runoff= precipitation + evapotranspiration +/- changes in storage
Runoff= how much water stays on the surface
Precipitation= input of water
Evapotranspiration= output of water
Changes in storage= amount of water than can be stores
Why is the soil water budget useful?
It allows us to understand more about the balance of drainage basin processes over the course of a year.
We can use them to predict when a river’s levels are likely to be higher (flood risk) or lower.
What is soil moisture surplus?
Occurs during late winter/early spring when inputs of precipitation exceed outputs of evapotranspiration.
The soil pores are saturated, meaning that water can’t infiltrate and stays on the surface.
What is soil moisture utilisation?
Occurs during later spring/early summer.
Evapotranspiration exceeds precipiation.
Water is also taken up by the roots of growing plants, and is initially replaced by water infiltrating from the surface (until it runs out).
What is soil moisture recharge?
Soil moisture stores are slowly replenished as precipitation exceeds evapotranspiration.
Soil pores slowly fill up with water until they become saturated- this is known as FIELD CAPACITY.
What is soil moisture deficit?
Towards the middle and late summer, all the stores of water in the soil have been used up by plants and lost through evapotranspiration(which has exceeded precipitation for a long time).
This only really occurs in more arid locations.
Soil moisture budget in Spring.
Evapotranspiration > precipitation.
Soil moisture utilisation by growing plants leaves the soil depleted of water.
River levels start to fall.
Soil moisture budget in Summer.
Evapotranspiration > precipitation
All soil moisture has been used up.
Soil moisture deficit means that infiltration levels are at their highest.
River levels are at their lowest.
Soil moisture budget in Autumn.
Precipitation > evapotranspiration
Soil moisture recharge as excess precipitation recharges soil water storeage until it reaches field capacity.
River levels slowly rise.
Soil moisture budget in Winter.
Precipitation > evapotranspiration
Soil moisture excess means the soil is saturated.
No infiltration takes place, so river levels are at their highest.
Which seasons will most water percolate into bedrock/groundwater stores and what will it cause?
Winter and spring as there will be more water in the soil.
This will cause the water table to rise causing higher river channel levels as more groundwater (baseflow), soil water (throughflow) and surface water (overland flow) will flow into the river.
In which season could there be a moisture deficit and why?
Summer due to low precipitation inputs and higher evapotranspiration output.
The soil dries and the water tabel drops- leading to lower river channel levels.
What causes summer floods?
If soil conditions are so dry that infiltration is difficult and the intensity of the storm is too great to allow the soil time to ‘soak’ up the water, summer floods could occur.
What is the mouth?
Where a river flows into a larger body of water.
What is a tributary?
A stream or river that flows into a larger stream or river.
What is the floodplain?
A flat area of land next to a river which is subject to flooding.
What is a drainage basin?
The area of land around the river that is drained by the river and its tributaries.
What is a confluence?
A flowing together of two or more streams.
What is a watershed?
An area of land that drains water into a specific waterbody.
What is the source of a river?
Starting point where the river begins in high ground.
What is precipitation?
Water that falls to the earth in any form: rain, sleet, hail and snow.
What is evaporation?
Moisture lost into the atmosphere by sun’s heat and wind.
What is transpiration?
Biological process where water is lost through minute pores in plants.
What is interception?
Raindrops fall on vegetation, preventing it from reaching the soil and river.
What is stemflow and throughfall?
Water reaches the ground by flowing down trunks or stems or by dropping off leaves.
What is infiltration?
The passage of water into the soil. This takes place quickly at the beginning of a storm, but as soil becomes saturated, infiltration falls rapidly.
Sand= high infiltration
Clay= less infiltration.
What is groundwater flow?
Water in this zone moves laterally at a very slow rate (it can take thousands of years to reach the river) to the river and provides the main input of water into a river during a dry season.
Often called baseflow.
What is percolation?
Water reaches underlying rock and its progress slows. This vertical movement is called percolation and it depends on the nature of the rock.
What is throughflow?
Water flows laterally through the soil to the channel.
What is surface runoff?
Movement of water above the soil. Occurs during heavy rainfall or when the ground is saturated.
Very rare except in urban areas.
What is channel fall?
Precipitation directly entering the river channel.
What is surface storage?
Water stored on the surface on the earth.
What is soil storage?
Water stored in soil above the water table.
What is the water table?
The boundary between saturated and unsaturated soils.
What is groundwater storage?
Water stored below the water table in saturated soil or rock.
What are inputs into the drainage system?
Precipitation
What are transfers in the drainage basin?
Channel fall
Interception
Through flow
Infiltration
Percolation
Groundwater flow
Overland flow
Stemflow
What are stores in the drainage basin?
Soil storage
Surface water
Groundwater
What are outputs in the drainage basin?
Transpiration
Evaporation
What is the fastest way for water to get to a river?
Overland flow
When is overland flow more likely to happen?
Deforestation- less interception
Steep relief- too fast to infiltrate
Impermeable surfaces- cannot infiltrate
Agricultural machinery- compressed soils saturate faster
Impermeable bedrock- prevents percolation
Snow melt/heavy precipitation- rapid infiltration leads to saturated soils.
What is the slowest way for water to get to a river and why?
Throughflow and groundwater flow.
Water can infiltrate into the soil and also percolate into the saturate groundwater stores below.
Water travels slowly to the river through pores in the rock so the river fills very slowly and floods are unlikely to occur.
When is throughflow and groundwater flow likely to occur?
Reforestation- increased interception
Flat ground- encourages infiltration
Permeable green spaces- infiltration
Permeable rock deep underground- percolation occurs preventing soil becoming saturated.
What does the speed of throughflow depend on?
Depth and texture of the soil.
Coare and sandy soil absorbs and transfers water quickly, especially through ‘pipes’ in the soil caused by animal activity or the growth of plant roots- increasing flood risk.
Such soils have a low field capacity as retain very little water in storage.
Name a type of soil with a high field capacity.
Clay soils.
These soils tend to be wet as they have tiny pore spaces which do not allow water to transfer easily.
What happens if bedrock is impermeable?
No further downward movement of water will occur.
What happens if bedrock is permeable?
Water will seep into cracks and holes within the rock and pass through slowly over the course of tens to hundereds of years- providing an important water store in arid areas.
What rocks can transmit water easily and an example?
Jointed rocks for example limestone.
Cheddar Gorge (limestone) in Somerset has a water flow of a calculated rate of 683cm per hour, this is considerabke faster then throughflow in the soil.
What are sandstone flow rates like and what are unconsolidated gravel flow rates like?
SS= 200cm per hour
UCG= 20000cm per hour
What type of vegetation covers semi-arid regions?
Scrub/bush
What type of vegetation covers temperate regions?
Grassland
What type of vegetation covers high latitudes?
Coniferous forest/tundra
How much of the River Severn’s catchment is forest?
67.5%
How much of the River Wye’s catchment is forest?
1.2%
How much of precipitation is lost through evaporation of intercepted stores in the River Severn’s catchment?
38%
How much of precipitation is lost through evaporation of intercepted stores in the River Wye’s catchment?
17%
How much water is lost per year through interception from cereal crops?
7-15% in growing season
How much water is lost per year through interception from temperate deciduous forest?
20% with leaves (spring/summer)
17% without leaves (autumn/winter)
How much water is lost per year through interception from coniferous forests?
30-35%
How much water is lost per year through interception from clover pastures?
40% in growing season
How much water is lost per year through interception from grass?
30-60%
How much water is lost per year through interception from brazilian evergreen forest?
66%
What is the water balance equation?
P= O + E +/- S
S= P - O - E
P= precipitation
O= total runoff (streamflow)
E= evapotranspiration
S= storage (in soil and rock)
Why is the water balance equation useful?
It helps hydrologists plan for future water supply and flood control.
