earth’s life support systems Flashcards

Question

what % of global water is in lakes?

Answer 1

fresh water comprises only a tiny proportion of water in store and three quarters is frozen in the ice caps of Antarctica and Greenland meanwhile, water stored below ground in permeable rocks amounts to just one fifth of all fresh water

Answer 2

water vapour evaporated from the oceans, soils, lakes and rivers vapour transpired through leaves of plants aka evapotranspiration

Answer 3

600 billion tonnes

Answer 4

38,700 billion tonnes

Answer 5

60,000-100,000,000 billion tonnes

Answer 6

6000 billion tonnes

Answer 7

4130 billion tonnes

Answer 8

560 billion tonnes

Answer 9

2300 billion tonnes

Answer 10

carbon stored in rocks, sea floor sediments and fossil fuels is locked away for millions of years. the total amount of carbon circulated by this slow cycle is between ten and 100 million tonnes a year CO2 diffuses from the atmosphere into the oceans where marine organisms, such as clams and corals, make their shells and skeletons by forming CaCO3. When they die the remains of these organisms sink to the ocean floor. There they accumulate and over millions of years, heat and pressure convert them into carbon-rich sedimentary rocks some carbon rich sedimentary rocks, subducted into the upper mantle at tectonic plate boundaries, are vented to the atmosphere in volcanic eruptions. Others exposed at or near the surface by erosion and tectonic movements are attacked by chemical weathering. this releases CO2 to atmosphere and, when in dissolved form, to streams, rivers and oceans on land, partly decomposed organic material may be buried beneath younger sediments to form carbonaceous rocks such as coal, lignite, oil and natural gas. These act as carbon sinks that endure for millions of years

Answer 11

carbon circulates most rapidly between the atmosphere, the oceans, living organisms and soils. these transfers are between ten and 1000 times faster than those in the slow carbon cycle land plants and phytoplankton in the oceans are the key components. they absorb CO2 from atmosphere via photosynthesis, and release it via respiration atmospheric CO2 dissolves in ocean surface waters while the oceans ventilate CO2 back to the atmosphere. Through this exchange individual carbon atoms are stored in the oceans for on average around 350 years

Answer 12

summarises the flows of water in a drainage basin over time it states that precipitation = evaporation + streamflow, plus or minus water entering or leaving storage

Answer 13

water and ice that falls from clouds towards the ground forms when vapour in the atmosphere cools to its dew point and condenses into tiny water droplets or ice particles to form clouds. Eventually these droplets or ice particles aggregate, reach a critical size and leave the cloud as precipitation

Answer 14

most rain on reaching the ground flows quickly into streams and rivers, But in high latitudes and mountainous catchments, precipitation often falls as snow and may remain on the ground for several months. Thus there may be a considerable time lag between snowfall and runoff high intensity precipitation moves rapidly overland into streams and rivers, because it is falling at a rate that exceeds the infiltration capacity of the soil prolonged events, linked to depressions and frontal systems, may deposit exceptional amounts of precipitation and cause saturation of the soil which leads to overland flow, and possibly river flooding in some parts of the world eg East Africa and Mediterranean, precipitation is concentrated in a rainy season so river discharge is high and flooding is common, and in the dry season rivers may cease to flow altogether

Answer 15

the diffusion of water vapour to the atmosphere from the stomata plants. responsible for around 10% of moisture in the atmosphere. influenced by temperature and wind speed and water availability to plants

Answer 16

to reduce moisture loss through transpiration

Answer 17

cumuliform clouds, with flat bases and considerable vertical development, most often from when air is heated locally through contact with the Earth's surface this causes heated air parcels to rise freely through the atmosphere (convection), expand and cool. As cooling reaches the dew point, condensation begins and clouds form

Answer 18

stratiform or layer clouds develop when an air mass moves horizontally across a cooler surface (often the ocean). this process, together with some mixing and turbulence, is known as advection

Answer 19

wispy cirrus clouds, which form at high altitude, consist of tiny ice crystals. unlike cumuliform and stratiform clouds they do not produce precipitation and therefore have little influence on the water cycle

Answer 20

they are visible aggregates of water or ice (or both) that float in the free air

Answer 21

- when air, warmed by contact with the ground or sea surface, rises freely through the atmosphere. As the air rises and pressure falls it cools by expansion (adiabatic expansion). This vertical movement of air is known as convection - when air moves horizontally across a relatively cooler surface-- a process known as advection - when air masses rise as they cross a mountain barrier or as turbulence forces their ascent - when a relatively warm air mass mixes with a cooler one

Answer 22

they describe the vertical distribution of temperature in the lower atmosphere, and the temp changes that occur within an air parcel as it rises vertically away from the ground

Answer 23

environmental lapse rate (ELR) dry adiabatic lapse rate (DALR) saturated adiabatic lapse rate (SALR)

Answer 24

the ELR is the vertical temperature profile of the lower atmosphere at any given time on average the temperature falls by 6.5 degrees celcius for every km of height gained

Answer 25

the DALR is the rate at which a parcel of dry air (ie less than 100 per cent humidity so that condensation is not taking place) cools. Cooling, caused by adiabatic expansion, is approximately 10 degrees celcius per km

Answer 26

the SALR is the rate at which a saturated parcel of air (ie one in which condensation is occuring) cools as it rises through the atmosphere. Because condensation releases latent heat, the SALR, at around 7 degreesC/km is lower than the DALR

Answer 27

precipitation develops when the tiny water droplets formed by condensation in saturated air grow until they are heavy enough to fall to the ground through any rising air currents beneath this happens either through a complex process of droplets coalescing as they collide with each other in turbulent air or by ice crystals growing within clouds as they rise and fall

Answer 28

- interception storage capacity. as vegetation becomes saturated, output of water through stemflow and throughfall increases. Interception therefore depends on the duration and intensity of a rainfall event - wind speed. evaporation increases with wind speed. turbulence also increases with wind speed causing additional through fall - vegetation type. interception losses are greater from grasses than from agricultural crops. Trees, which have a large surface area and aerodynamic roughness, have higher interception losses than grasses - tree species. interception losses are far greater from evergreen conifers than from broad leaved deciduous trees, bc most conifers have leaves all year round and water adheres to spaces between conifer needles, increasing evaporation

Answer 29

rainwater that is briefly intercepted before dripping to the ground is known as throughfall

Answer 30

during periods of prolonged or intense rainfall, intercepted rainwater may flow to the ground along branches and stems as stemflow

Answer 31

the idea that overland flow only occurs when soil becomes saturated and the water table rises to the surface

Answer 32

when soils are underlain by permeable rocks, water seeps or percolates deep underground. This water then migrates slowly through the rock pores and joints as groundwater flow, eventually emerging at the surface as springs or seepages

Answer 33

precipitation photosynthesis weathering respiration decomposition combustion

Answer 34

atmospheric CO2 dissolves in rainwater to form weak carbonic acid rising concentrations of CO2 in the atmosphere, due to anthropogenic emissions, have increased the acidity of rainfall. This has contributed to increased acidity of ocean surface waters with potentially harmful effects on marine life

Answer 35

120GT a year

Answer 36

rainwater is a weak carbonic acid, which slowly dissolves limestone and chalk in a process known as carbonation carbonation releases carbon from limestones to streams, rivers, oceans and the atmosphere. The process is most effective beneath a soil cover because the higher concentration of CO2 in the soil makes rainwater highly acidic

Answer 37

combustion is a natural fuel used in many ecosystems. wildfires caused by lightning strikes are essential to the health of some ecosystems such as the coniferous forests of the Rocky Mountains. Long, cold winters slow the decomposition of forest litter which builds up on the forest floor. Fire shifts this log jam, freeing carbon and nutrients previously inaccessible to forest trees currently the burning of fossil fuels transfers nearly 10GT of CO2 a year from geological store to the atmosphere, oceans and biosphere

Answer 38

involves the mixing of surface and deep ocean waters by vertical currents, creating a more even distribution of carbon in the oceans initially, CO2 enters the oceans from the atmosphere by diffusion. Surface ocean currents then transport the water and its dissolved CO2 polewards where it cools, becomes more dense and sinks. this downwelling occurs in only a handful of places in the oceans eg the north atlantic between greenland and iceland downwelling carries dissolved carbon to the ocean depths where individual carbon molecules may remain for centuries eventually, deep ocean currents transport the carbon to areas of upwelling. There cold, carbon rich water rises to the surface and CO2 diffuses back into the atmosphere

Answer 39

around 50 GT of carbon is drawn from the atmosphere by the biological pump every year marine organisms drive the biological pump. phytoplankton floating near the ocean surface produce organic material. Whether consumed by animals or through natural death, carbon locked in the phytoplankton either accumulates in sediments on the ocean floor or is decomposed and released into the ocean as CO2 other marine organisms such as molluscs extract carbonate and calcium ions from sea water to manufacture plates, shells and skeletons of calcium carbonate. most of this carbon rich material eventually ends up in the ocean sediments and is ultimately lithified to form chalk and limestone

Answer 40

occupies more than 6 million km2 of land. 70 percent is in Brazil, but parts also extend into Peru, Ecuador, Venezuela, Colombia, Bolivia and Guyana

Answer 41

high average annual temperatures between 25 degreesC and 30 degreesC small seasonal variation in temperature high average annual rainfall (>2000mm) with no dry season

Answer 42

high average rainfall rainfall fairly evenly distributed throughout the year though short drier season occurs in some places high intensity convectional rainfall interception by forest trees is high (around 10 per cent of precipitation). Intercepted rainfall accounts for 20-25 per cent of all evaporation

Answer 43

high rates due to high temps, abundant moisture and dense vegetation strong evapotranspiration-precipitation feedback loops sustain high rainfall totals around a half of incoming rainfall is returned to the atmosphere by evapotranspiration most evaporation is from intercepted moisture from leaf surface. moisture lost in transpiration is derived from the soil via tree roots

Answer 44

rapid run off related to high rainfall events and well-drained soils depending on seasonal distribution of rainfall, river discharge may peak in one or two months of the year

Answer 45

high temperatures allow the atmosphere to store large amounts of moisture, ie absolute humidity is high relative humidity is also high

Answer 46

abundant rainfall and deep tropical soils lead to significant water storage in soils and aquifers

Answer 47

rainforest trees play a crucial role in the water cycle, absorbing and storing water from the soil and releasing it through transpiration

Answer 48

is high averaging 2500 grams/m2/year the biomass is between 400 and 700 tonnes/ha

Answer 49

2.4 billion tonnes a year

Answer 50

rapid compared to other forest ecosystems warm, humid conditions ensure speedy decomposition of dead organic matter and the quick release of CO2 meanwhile rates of carbon fixation through photosynthesis are high

Answer 51

impermeable catchments (eg large of the Amazon Basin are an ancient shield area comprising impermeable, crystalline rocks) have minimal water storage capacity, resulting in rapid run off permeable and porous rocks such as limestone and sandstone store rainwater and slow run off

Answer 52

most of the amazon basin comprises extensive lowlands in areas of gentle relief, water moves across the surface or horizontally though the soil to streams and rivers in the west the Andes create steep catchments with rapid run off. widespread inundation across extensive floodplains (eg the Pantanal) occurs annually, storing water for several months and slowing its movement into rivers

Answer 53

high temps throughout the year generate high rates of evapotranspiration convection is strong, leading to high atmospheric humidity, the development of thunderstorm clouds and intense precipitation water is cycled continually between the land surface, forest trees and the atmosphere by evaporation, transpiration and precipitation

Answer 54

60% of rainforest carbon is stored in the above ground biomass of tree stems, branches and leaves the remainder is below ground, mainly as roots and soil organic matter

Answer 55

leaf litter and other dead organic matter accumulates temporarily at the soil surface and within rainforest soils high temps and humid conditions promote rapid decomposition of organic litter by bacteria, fungi and other soil organisms. decomposition releases nutrients to the soil for immediate take up by tree root systems and emits CO2 which is returned to the atmosphere **carbonates are largely absent from the mineral composition of rocks in the Amazon Basin, but in the western parts, outcrops of limestone do occur, which are significant regional carbon stores in the context of the slow carbon cycle**

Answer 56

deforestation in Amazonia averaged around 17,500km2/year between 1970 and 2013 since 1970, almost one fifth of the primary forest has been destroyed or degraded since 2009, annual rates have been lower than the average but have started to rise again in recent years

Answer 57

devastating floods occurred on the Madeira River, the largest tributary of the Amazon River At Port Velho the river reached record levels of 19.68m above normal vast expanses of floodplain were inundated; 60 people died; 68,000 families were evacuated; and there were outbreaks of cholera and leptospirosis

Answer 58

has modified stores and flows in the water cycle deforestation has reduced water storage in forest trees, soils (which have been eroded), permeable rocks (due to more rapid run off) and in the atmosphere fewer trees means less evapot and therefore less precip total run off and run off speeds have increased, raising flood risks throughout the basin

Answer 59

converting rainforest to grassland increases run off by a factor of 27, and half of all rain falling on grassland goes directly into rivers deforestation breaks the normal cycle and can lead to permanent climate change **projections of future deforestation in Amazonia predict a 20 per cent decline in regional rainfall as the rainforest dries out and forest trees are gradually replaced by grassland**

Answer 60

deforestation exhausts the carbon biomass store croplands and pasture contain only a small amount of carbon compared to forest trees drastically reduces inputs of organic material to the soil. this means the soil supports fewer decomposer organisms, thus reducing the flow of carbon from the soil to the atmosphere deforestation destroys the main nutrient store (the forest trees) and removes most nutrients from the ecosystem. Nutrients no longer taken up by the root systems of trees are washed out of soils by rainwater; and soils, without the protective cover of trees, are quickly eroded by run off

Answer 61

indigenous people have lived sustainably in the rainforest for thousands of years, maintaining the water balance, carbon cycle and the forest's biodiversity these people survived as hunter-gatherers and shifting cultivators indigenous people pursued a way of life perfectly adapted to the limited resources and fragility of the rainforest

Answer 62

a traditional method of cultivation in tropical rainforests, which involves rotation of land rather than rotation of crops

Answer 63

- protection through legalisation of large expanses of primary forest so far unaffected by commercial developments - projects to reforest areas degraded or destroyed by subsistence farming, cattle ranching, logging and mining - improving agricultural techniques to make permanent cultivation possible

Answer 64

since 1998, the Brazilian government has established many forest conservation areas these Amazon Regional Protected Areas now cover an area 20 times the size of Belgium. By 2015, 44% of the Brazilian Amazon comprised national parks, wildlife reserves and indigenous reserves where farming is bad

Answer 65

several reforestation projects sponsored by local authorities, NGOs and businesses underway eg the Parica project in Rondônia in the western Amazon this sustainable forestry scheme aims to develop a 1000km2 commercial timber plantation on government-owned deforested land. Plan is for 20 million fast-growing tropical hardwood seedlings, planted on 4000 smallholdings, to mature over a period of 25 years financial assistance given to the smallholders for land preparation, planting and the maintenance of plots. Tree nurseries provide them with seedlings. Timber will be exported along the Amazon and its tributaries through Manaus or Port Velho STRENGTHS: sustainable, sequesters carbon into trees and soil, reduces CO2 emissions, re-establishes cycles and reduces run off WEAKNESSES: cannot replicate the biodiversity of the primary rainforest

Answer 66

in Rondônia, they participate in a scheme that aims to protect primary rainforest on tribal lands from further illegal logging, and reforest areas degraded by deforestation in the past 40 years they plant seedlings bred in local nurseries in deforested areas around their villages. The native species planted are chosen to provide them with timber for construction, food crops and a sustainable source of income through logging 2009- were the first indigenous group in Amazonia to join UN's Reducing Emissions from Deforestation and Degradation (REDD) scheme. This scheme provides payment to the tribe for protecting the rainforest and abandoning logging

Answer 67

occupies some 8 million km2 in northern Canada, Alaska and Siberia extends from the northern edge of the boreal coniferous forest to the Arctic Ocean and its southern limit approximates the 10degreesC July isotherm

Answer 68

mean temps below -15degreesC for 8 or 9 months a year the tundra has a negative heat balance with avrg monthly temps below freezing the ground is permanently frozen with only the top metre or so thawing during the Arctic summer in winter, when for several weeks the sun remains below the horizon, temps can plunge below -40C mean annual precipitation is low

Answer 69

biodiversity low apart from a few dwarf species, the ecosystem is treeless in the southern areas -- the Low Arctic -- conditions are less severe, and vegetation provides a continuous ground cover. Further north in the High Arctic, plant cover is discontinuous with extensive areas of bare ground

Answer 70

low annual precipitation (less than 100mm in most places) with most precipitation falling snow small stores of moisture in the atmosphere owing to low temps which reduce absolute humidity limited transpiration because of the sparseness of the vegetation cover and the short growing season of 3 months low rates of evaporation. much of the sun's energy in summer is expended melting snow so that ground temps remain low and inhibit convection. Also, surface and soil water are frozen for most of the year limited groundwater and soil moisture stores. permafrost is a barrier to infiltration, percolation, recharge and groundwater flow accumulation of snow and river/lake ice during winter months. melting causes sharp increase in river flow, eg Yukon River min discharge of 340 cumecs in winter and a max of 24,600 cumecs in summer extensive wetlands, ponds and lakes on the tundra during summer bc permafrost impedes drainage, eg in Yukon River, Alaska

Answer 71

the flux of carbon is concentrated in the summer months when the active layer thaws. **Plants such as sedges, crowberry and moss grow rapidly**. Long hours of daylight allow them to flower and fruit within a few weeks. Nonetheless, NPP is less than 200 grams/m2/year during the growing season tundra plants input carbon-rich litter to the soil. increased activity of microorgamisms + respiration

Answer 72

pockets of unfrozen soil and water in the permafrost act as sources of CO2 and CH4 snow cover may insulate microbial organisms and allow some decomposition despite the low temps

Answer 73

avrg temps well below freezing for most of the year = permafrost = poor drainage in winter, subzero temps preventn evapot. in summer, some evapot occurs from standing water, saturated soils and vegetation. humidity is low all year round and precipitation is sparse permeability is low owing to the permafrost and the Precambrian igneous and metamorphic rocks which dominate the geology of the tundra in Alaska The ancient rock surface which underlies the tundra has been reduced to a gently undulating plain by hundreds of millions of years of erosion and weathering. minimal relief and chaotic glacial deposits impede drainage and contribute to waterlogging during the summer months

Answer 74

carbon is mainly stored as partly decomposed plant remains frozen in the permafrost. Most of this carbon has been locked away for at least the past 500,000 years low temps, the unavailability of liquid water for most of the year and parent rocks containing few nutrients all limit plant growth. Thus the total carbon store of the biomass is relatively small. Averaged over the year, photosynthesis and NPP are low with the growing season lasting barely 3 months. However there is some compensation for the short growing season in the long hours of daylight in the summer low temps and waterlogging slow decomposition and respiration and the flow of CO2 to the atmosphere owing to the impermeability of the permafrost, rock permeability, porosity and the mineral composition of rocks exert little influence on the water and carbon cycle

Answer 75

a harsh climate with extreme cold and long periods of darkness in winter permafrost and the melting of the active layer in summer remoteness and poor accessibility fragile wilderness of great ecological validity

Answer 76

construction and operation of oil and gas installations, settlements and infrastructure diffusing heat directly to the environment dust deposition along roadsides creating darkened snow surfaces, thus increasing absorption of sunlight removal of the vegetation cover which insulates the permafrost

Answer 77

vary from 7 to 40 million/tonnes/year while CH4 losses range from 24,000 to 114,000 tonnes/year

Answer 78

they are linked to industrial development the destruction and degrading of tundra vegetation reduces photosynthesis and the uptake of CO2 from the atmosphere the thawing of soil increases microbial activity, decomposition and emissions of CO2 the slow growing nature of tundra vegetation means that regeneration and recovery from damage takes decades

Answer 79

melting of the permafrost and snow cover increases run off and river discharge, making flooding more likely strip mining of aggregates for construction creates artificial lakes which disrupt drainage and also exposes the permafrost to further melting artificial lakes at Goldstream, near Fairbanks, have experienced 15m permafrost thaw in the last 60 years drainage networks are disrupted by road construction and seismic explosions used to prospect for oil and gas water abstracted from creeks and rivers for industrial use and for the building of ice roads in winter, such as the one between Fairbanks and Prudhoe Bay, reduce localised run-off. BP extracts most of the water it need from the Kuparuk River and Big Lake

Answer 80

roads and other infrastructural features can be constructed on insulating ice or gravel pads, thus protecting the permafrost from melting. The Spine Road and Prudhoe Bay lies on a 2m deep pad

Answer 81

constructing buildings, oil/gas pipelines and other infrastructure on piles allows cold air to circulate beneath these structures. This provides insulation against heat-generating buildings, pipework etc, which would otherwise melt the permafrost

Answer 82

new drilling techniques allow oil and gas to be accessed several km from the drilling site Shell has developed the 'snake drill' which allows directional drilling across a wide area from a single drilling site. With a fewer sites needed for drilling rigs, the impact on vegetation and the permafrost due to construction (access roads, pipelines, production facilities etc) is greatly reduced

Answer 83

fewer exploration wells are needed thus reducing the impact on the environment about 10% of all supercomputers have been delivered to the oil industry. Its two big computational tasks are seismic data processing (to deduce underground geological structures), and reservoir modelling (to stimulate the flows within a producing field, in order to optimise the amount of oil that can be recovered

Answer 84

refrigerated supports are used on the Trans-Alaskan Pipeline to stabilise the temp of the permafrost similar supports are widely used to conserve the permafrost beneath buildings and other infrastructure

Answer 85

a system, displaying unrepeated average states through time

Answer 86

negative feedback loops within stores restore balance

Answer 87

in a drainage basin, unusually heavy rainfall will increase the amount of water stored in aquifers this in turn will raise the water table, increasing flow from springs until the water table reverts to normal levels

Answer 88

burning fossil fuels increases atmospheric CO2 but at the same time stimulates photosynthesis. This negative feedback response should remove excess CO2 from the atmosphere and restore equilibrium

Answer 89

artificial surfaces are largely impermeable so they allow little to no infiltration and provide minimal water storage capacity to buffer run off drainage systems = high proportion of water from precipitation flows quickly into streams and rivers, leading to a rapid rise in water level

Answer 90

development on floodplains reduces water storage capacity in drainage basins, increasing river flow and flood risk drainage systems = rapid rise in water level of streams

Answer 91

the removal of vegetation and its replacement with urban surfaces results in reduced amounts of organic carbon the development of factories and homes, along with increased vehicle usage, results in the release of carbon dioxide into the atmosphere from the burning of fossil fuels

Answer 92

crop irrigation diverts surface water from rivers and groundwater to cultivated land. Some of this water is extracted by crops from soil storage and released by transpiration, but most is lost to evap and in soil drainage interception of rainfall by annual crops is less than in the forest and grassland ecosystems, as well as evapot from leaf surfaces ploughing increases evap and soil moisture loss, and furrows ploughed downslope act as drainage channels, accelerating run off and soil erosion infiltration due to ploughing is usually greater in farming systems, while artificial underdrainage increases the rate of water transfer to streams and rivers. Surface run off increases where heavy machinery compacts soils, thus peak flows on streams draining farmland are generally higher than in natural ecosystems

Answer 93

the clearance of forest for farming reduces carbon storage in both the above and below ground biomass soil carbon storage reduced by ploughing and the exposure of soil organic matter to oxidation. further losses occur through the harvesting of crops, with only small amounts of organic matter returned to soils. changes to the carbon cycle are less apparent on pasture land or when farming replaces natural grasslands. Eg in NA, the NPP of annual crops ie wheat on the Great PLains exceeds that of the original Prairie grasslands. However, carbon exchanges through photosynthesis are generally lower than in natural ecosystems, partly bc of a lack of biodiversity in farmed systems, and the growth cycle of crops is often compressed into just four or five months

Answer 94

higher rates of rainfall interception in plantations in natural forests. In eastern England, interception rates for Sitka spuce are as high as 60%. In upland Britain, where temps and evap are lower, interception is about this figure. In the UK, preferred plantation species are conifers. The needle-like structure of conifer leaves, their evergreen habit and high density of planting all contribute to high rates of interception

Answer 95

increased evap a large proportion of intercepted rainfall is stored on leaf surfaces and is evaporated directly into the atmosphere

Answer 96

reduced run off and stream discharge with high interception and evap rates, and the absorption of water by tree roots, drainage basin hydrology is altered. Streams draining plantations typically have relatively long lag times, low peak flows and low total discharge. The effect of conifer plantations in upland catchments is often to reduce water yield for public supply

Answer 97

compared to farmland and moorland, transpiration rates are increased. Typical transpiration rates for Sitka spruce in the Pennines are around 350mm/year of rainfall equivalent

Answer 98

clear feeling to harvest timber creates sudden but temporary changes to the local water cycle, increasing run off, reducing evapot, and increasing stream discharge

Answer 99

after 100 years after planting, the amount of carbon captured levels off and is balanced by inputs of litter to the soil, the release of CO2 in respiration and by activities of soil decomposers, therefore forestry plantations cycle 80-100 years to remain a carbon sink forestry increases plant stores, as trees extract CO2 from the atmosphere and sequester it for hundreds of years **in a typical plantation in the UK, mature forest trees contain an average of 170-200 tonnes C/ha, which is 10x higher than grassland**

Answer 100

the River Kennet in southern England drains an area of around 1200km2 in Wiltshire and Berkshire. the upper catchment mainly comprises chalk which is mainly permeable. Thus groundwater contributes most of the Kennet's flow As a chalk stream, the river supports a diverse range of habitats and wildlife. Its water. filtered through chalk, has exceptional clarity, high oxygen levels and is fast moving. Among the native fauna are Atlantic salmon, brown trout, water voles, otters and white clawed crayfish

Answer 101

within and close to the catchment, several urban areas rely on water from the Kennet basin to meet public supply Swindon, the largest, has a population of over 220,000. The Kennet also supplies water for local industries, agriculture and public use. Thames Water abstracts groundwater from the upper catchment from boreholes. None of this water is returned to the river as waste water

Answer 102

rates of groundwater extraction have exceeded rates of recharge, and the falling water table has reduced flows in the River Kennet by 10-14% during the 2003 drought, flows fell by 20%, and in the dry conditions of the early 1990s by up to 40% lower flows have reduced flooding and temporary areas of standing water and wetlands on the Kennet's floodplain between Marlborough and Hungerford Lower groundwater levels have caused springs and seepages to dry up and reduced the incidence of saturated overland flow on the chalk hills of the Marlborough Downs

Answer 103

permeable or porous water-bearing rocks such as chalk and New Red Sandstone groundwater is abstracted for public supply from aquifers by wells and boreholes emerging in springs and seepages, groundwater feeds rivers and makes a major contribution to their base flow within an aquifer the upper surface of saturation is known as the water table. Its heigh fluctuates seasonally and is also affected by periods of exceptional rainfall, drought and abstraction. In normal years in southern England, the water table falls between March and Sept, as rising temps increase evapot losses. Recharge resumes in late autumn

Answer 104

when sedimentary rocks form a syncline or basin like structure, an aquifer confined between impermeable rock layers may contain groundwater which is under artesian pressure if groundwater is tapped by a well or borehole, water will flow to the surface under its own pressure. this is known as an artesian aquifer the level to which the water will rise - the potentiometric surface - is determined by the height of the water table in areas of recharge on the edges of the basin

Answer 105

London is located at the centre of a synclinal structure which forms an artesian basin groundwater in the chalk aquifer is trapped between impermeable London clay and Gault clay. Rainwater enters the chalk aquifer where it outcrops on the edge of the basin in the North Downs and Chilterns Groundwater then flows by gravity through the chalk towards the centre of the basin. This under natural conditions the wells and boreholes in the London area are under artesian pressure

Answer 106

groundwater from the chalk is an important source of water for the capital. However, over exploitation in the 19th century and first half of 20th century caused a drastic fall in the water table. In central London it fell by nearly 90m In the past 50 years declining demand for water by industry in London and reduced rates of abstraction have allowed the water table to recover. By the early 1990s it was rising at a rate of 3m/year and began to threaten buildings and underground tunnels since 1992 Thames Water has been granted abstraction licences to slow the rise of the water table which is now stable

Answer 107

releases 10 billion tonnes of CO2 to the atmosphere annually, increasing atmospheric CO2 concentration by over 1ppm.

Answer 108

it involves three stages: first the CO2 is separated from power station emissions. the CO2 is then compressed and transported by pipeline to storage areas. And finally it is injected into porous rocks deep underground where it is stored permanently

Answer 109

the Drax project in North Yorkshire, designed to capture 2 million tonnes of CO2 per year, commenced operation in 2019. The plan is for the carbon to be transported by pipeline to the North Sea and stored in depleted gas reservoirs CO2 gas can also be pumped into 'mature' oilfields to extract oil that would otherwise be uneconomic to recover

Answer 110

it involves big capital costs - the Drax and Peterhead projects will cost at least £1 billion it uses large amounts of energy - typically 20 per cent of a power plant's output is needed to separate the CO2 and compress it requires storage reservoirs with specific geological conditions, ie porous rocks overlain by impermeable strata

Answer 111

occurs when an initial change causes further change

Answer 112

in a warmer world, evap increases and the atmosphere holds more vapour, resulting in greater cloud cover and more precipitation. These changes create a positive feedback effect. More vapour in the atmosphere increases absorption of long wave radiation from earth, causing further rises in temperatures alternatively, more atmospheric vapour can induce negative feedback. More vapour creates greater cloud cover which reflects more solar radiation back into space. And as smaller amounts of solar radiation are absorbed by the atmosphere, oceans and land, average global temps fall

Answer 113

in most years precipitation is sufficient to satisfy an individual tree's demand for water however, in drought years, shallow rooted trees like silver birch become stressed: water lost in transpiration is not replaced by a similar uptake of water from the soil. The tree responds, reducing transpiration losses by shedding some or all of its leaves. This negative feedback loop restores the water balance and ensures the tree's survival

Answer 114

process known as carbon fertilisation in this way, excess CO2 is extracted from the atmosphere and stored in the biosphere. Eventually much of this carbon would find its way into long-term storage in soils and ocean sediments, allowing the system to return to a steady state however, increased primary production through carbon fertilisation is conditional on the availability of other requirements for photosynthesis such as sunlight, soil nutrients, nitrogen and water. Therefore, it is not possible to say with certainty that primary production as increased due to increased atmospheric CO2 in recent years For instance, recently significant increases in primary production have been observed in the Amazon rainforest but this could be explained by lower rainfall, with less cloud cover and more sunlight rather than an increase in CO2

Answer 115

global warming will intensify the carbon cycle, speed up decomposition and release more CO2 to the atmosphere, thus amplifying the greenhouse effect

Answer 116

NASA's Earth Observing System (EOS) satellites have monitored sea ice growth and retreat since 1978 measures microwave energy radiating from the surface. Comparison of time series images to show changes

Answer 117

as well as ground-based estimates of mass balance, satellite technology eg ICESat-2 measures surface height of ice sheet and glaciers using laser technology. Shows extent and volume of ice and changes

Answer 118

NOAA satellites radiometers measure the wave band of radiation emitted from the ocean surface. Changes in global SSTs and areas of upwelling and downwelling

Answer 119

NOAA polar orbiters measures cloud liquid water, total precipitation water etc. Long-term trends in cloud cover and water vapour in the atmosphere

Answer 120

ESA albedo (reflectivity) images from various satellites measurements of reflectivity of Earth's surface and land use changes

Answer 121

NASA's Orbiting Carbon Observatory-2 (OCO-2) Ground-based measurements at Mauna Loa, Hawaii, since 1958 new satellite measurements of global atmospheric CO2 from NASA's OCO-2. The satellite also measures the effectiveness of absorption of CO2 by plants

Answer 122

NASA's MODIS/AQUA measures net primary production in oceans and on land

Answer 123

significant changes occur within a 24-hour period in the water cycle lower temps at nigh reduce evap and transpiration. Convectional precip, depending on direct heating of the ground surface by the Sun, is a daytime phenomenon often falling in the afternoon when temps reach a max this is particularly significant in climactic regions in the tropics where the bulk of precipitation is from convectional storms

Answer 124

during the daytime CO2 flows from the atmosphere to vegetation. At night the flux is reversed. Without sunlight, photosynthesis switches off, and vegetation loses CO2 to the atmosphere. The same diurnal pattern is observed with phytoplankton in the oceans

Answer 125

higher levels of solar input in the summer result in higher evapot. in the driest parts of lowland England, up to 80% of precip may be lost to evapot. with large losses of precip to evapot and the exhaustion of soil moisture, river flows in England are normally at their lowest in summer

Answer 126

shown by month-to-month changes in the NPP of vegetation in middle and high latitudes, day length of photoperiod, and temperature drive seasonal changes in NPP. Similar seasonal variations also occur in the tropics, though there the main cause is water availability during the northern hemisphere summer, when trees are in full foliage, there is a net global flow of CO2 from the atmosphere to the biosphere. This causes atmospheric CO2 levels to falll by 2 ppm. At the end of summer, as photosynthesis ends, the flow is reversed with natural decomposition releasing CO2 back to the atmosphere. Seasonal fluctuations in the global CO2 flux are explained by the concentration of continental and masses in the northern hemisphere. During the growing season, ecosystems such as the boreal and temperate forests extract huge amounts of CO2 from the atmosphere, which has a global impact in the oceans phytoplankton are stimulated into photosynthetic activity by rising water temps, more intense sunlight and the lengthening photoperiod. Every year in the North Atlantic there is an explosion of microscopic oceanic plant life which starts in March and peaks in mid-summer, The resulting algal blooms are so extensive, they are visible from space

Answer 127

during glacial periods the water cycle undergoes a number of changes. the most obvious is the net transfer of water from the ocean reservoir to storage in ice sheets, glaciers and permafrost as a result, in glacials the sea level worldwide falls by 100-130m; and ice sheets and glaciers expand to cover around one-third of the continental land mass. As ice sheets advance Equator-wards they destroy extensive tracts of forest and grassland, The area covered by vegetation and water stored in the biosphere shrinks. Meanwhile, in the tropics, the climate becomes drier and deserts and grasslands displace large areas of rainforest lower rates of evapot during glacial phases reduce exchanges of water between the atmosphere and the oceans, biosphere and soils. This, together with so much freshwater stored as snow and ice, slows the water cycle appreciably

Answer 128

there is a dramatic reduction in CO2 in the atmosphere during glacial periods. At times of glacial maxima, CO2 concentrations fall to around 180 ppm, while in warmer interglacial periods they are 100ppm higher no clear explanation exists for the drop in atmospheric CO2 during glacial periods. It is, however, possible that excess CO2 finds its way from the atmosphere to the deep ocean. One mechanism is changes in ocean circulation during glacials that bring nutrients to the surface and stimulate phytoplankton growth. Phytoplankton fix large amounts of CO2 by photosynthesis before dying and sinking to the deep ocean where carbon is stored. Lower ocean temps also make CO2 more soluble in surface waters other changes occur in the terrestrial biosphere. The carbon pool in vegetation shrinks during glacials as ice sheets advance and occupy large areas of the continents. In this process deserts expand, tundra replaces temperate rainforests and grasslands encroach on tropical rainforests. Which much of the land surface buried by ice, carbon stored in soils will no longer be exchanged with the atmosphere. Meanwhile expanses of tundra beyond the ice limit sequester huge amounts of carbon in permafrost. With less vegetation cover, fewer forests, lower temps and lower precip, NPP and the total volume of carbon fixed in photosynthesis will decline. The implications are an overall slowing of the carbon flux and smaller amounts of CO2 returned to the atmosphere through decomposition

Answer 129

atmospheric CO2 has a greenhouse effect CO2 plays a vital role in photosynthesis by terrestrial plants and phytoplankton. Plants, which are important carbon stores, extract water from the soil and transpire it as part of the water cycle. Water is evaporated from the oceans to the atmosphere, and CO2 is exchanged between the two stores

Answer 130

ocean acidity increases when exchanges of CO2 are not in balance (ie inputs to the oceans from the atmosphere exceed outputs). The solubility of CO2 in the oceans increases with lower SSTs. Atmospheric Co2 levels influence SSts and the thermal expansion of the oceans; air temps; the melting of ice sheets and glaciers; and sea level

Answer 131

water availability influences rates of photosynthesis, NPP, inputs of organic litter to soils and transpiration the water storage capacity of soils increases with organic content temps and rainfall affect decomposition rates and the release of CO2 to the atmosphere

Answer 132

CO2 levels in the atmosphere determine the intensity of the greenhouse effect and melting of ice sheets, glaciers, sea ice and permafrost. Melting exposes land and sea surfaces which absorb more solar radiation and raise temps further. Permafrost melting exposes organic material to oxidation and decomposition which releases CO2 and CH4. Run off, river flow and evaporation respond to temp change

Answer 133

is most evident in rivers and aquifers rising demand for water for irrigation, agriculture and public supply, especially in arid and semi-arid environments, has created acute shortages in the Colorado Basin in the southwest USA, surface supplies have diminished as more water is abstracted from rivers, and huge amounts are evaporated from reservoirs like Lake Mead and Lake Powell. Elsewhere, the quality of fresh water sources has declined. Over pumping of aquifers in the coastal regions of Bangladesh has led to incursions of salt water, often making the water unfit for irrigation and drinking Compared to natural ecosystems, human activities such as deforestation and urbanisation reduce evapot and therefore precip; increase surface run off; decrease throughflow; and lower water tables. In Amazonia, forest trees are a key componenet of the water cycle, transferring water to the atmosphere by evapot, which is then returned through precip. In places, extensive deforestation has broken thiss cycle, causing climates to dry out and preventing regeneration of the rainforest

Answer 134

it is depleting carbon stores and increasing others exploitation of coal, oil and natural gas has removed billions of tonnes of carbon from geological store - a process that has gathered momentum in the past 30 years with the rapid industrialisation of the Chinese and Indian economies Currently around 8 billion tonnes of carbon a year are transferred to the atmosphere by burning fossil fuels. In addition, land use change (mainly deforestation) transfers approximately 1 billion tonnes of carbon to the atmosphere annually. The additional carbon is stored primarily as atmospheric CO2, where its concentration increases year-by-year. Around 2.5 million tonnes is absorbed by the biosphere, and a similar amount by the biosphere deforestation means carbon stored in biosphere has declined steeply. acidification of oceans threatens phytoplankton, which absorb more than half the CO2 from burning fossil fuels, which is significantly more than tropical rainforests soil is another important carbon store which is being degraded by erosion caused by deforestation and agricultural mismanagement. Carbon stores in wetlands, drained for cultivation and urban development, have also been depleted as they dry out and are oxidised

Answer 135

global warming as increased evaporation and therefore the amount of water vapour in the atmosphere. this has feedback effect, helping to raise global temperatures, increase evap and precip. meanwhile, increased precip will result in higher run-off in the water cycle and greater flood risks/ water vapour is also a source of energy in the atmosphere, releasing latent heat on condensation. With more energy in the atmosphere extreme weather events such as hurricanes and mid-latitude storms become more powerful and more frequent global warming is accelerating the melting of glaciers, ice sheets like Greenland and permafrost in the Arctic tundra. Thus water storage in the cryosphere shrinks, as water is transferred to the oceans and atmosphere

Answer 136

global warming = increased decomposition + transfer of carbon from biosphere + soil to atmosphere global warming = change in biomes = rainforests more arid, boreal forests expand in permafrost global warming = vast peat stores (tundra) decomposition acidification of oceans = limit phytoplankton = reduce carbon store

Answer 137

wetlands include freshwater marshes, salt marshes, peatlands, floodplains and mangroves. their common feature is a water table at or near the surface causing the ground to be permanently saturated in the lower 48 US states the wetland area has halved since 1600. The destruction of wetlands transfers huge amounts of stored CO2 and CH4 to the atmosphere in the twentieth century, Canada's prairie provinces lost 70% of their wetlands. Restoration programmes in this area have shown that wetlands can store on average 3.25 C/ha/year. Now 112,000 ha have been targeted for restoration in the Canadian prairies which should eventually sequester 364,000 tonnes C/year the need for protection of wetlands as wildlife habitats as well as carbon stores is reflected in management initiatives such as the International Convention on Wetlands (Ramsar) and European Union Habitats Directive restoration focuses on raising local water tables to re-create waterlogged conditions. Eg wetlands on floodplains can be reconnected to rivers by the removal of flood embankments and controlled floods. Coastal areas of reclaimed marshland used for farming can be restored by breaching sea defences elsewhere water levels can be maintained at artificially high levels by diverting or blocking drainage ditches and installing sluice gates

Answer 138

it involves planting trees in deforested areas or in areas that have never been forested because trees are carbon sinks, afforestation can help reduce atmospheric Co2 levels in the medium to long term and combat climate change. It also has other benefits such as reducing flood risks and soil erosion, and increasing biodiversity the UN's Reducing Emissions from Deforestation and Forest Degradation (REDD) scheme incentivises developing countries to conserve their rainforests by placing a monetary value on forest conservation. Several projects are already well established such as those in Amazonia (Puras, Russas-Valparaiso) and the Lower Mississipi In China a massive government-sponsored afforestation project began in 1978. It aims to afforest 400,000km2 by 2050. In the decade 2000-09, 30,000km2 were successfully planted with non-native, fast-growing species such as poplar and birch. However, the project has a wider purpose: to combat desertification and land degradation in the vast semi-arid expanses of northern China

Answer 139

zero tillage - growing crops without ploughing the soil. This conserves the soil's organic content, reducing oxidation and the risk of erosion by wind and water polyculture - growing annual crops interspersed with trees. Trees provide year-round ground cover and protect soils from erosion crop residues - leaving crop residues (stems, leaves etc) on fields after the harvest, to provide ground cover and protection against soil erosion and drying out avoiding the use of heavy farm machinery on wet soils, which leads to compaction and the risk of erosion by surface run-off contour ploughing and terracing on slopes to reduce run off and erosion introducing new strains of rice that grow in drier conditions and therefore produce less Ch4. Applying chemicals such as ammonium sulphate which inhibit microbial activities that produce CH4

Answer 140

improving the quality of animal feed to reduce enteric fermentation so that less feed is converted to CH4, mixing methane inhibitors with livestock feed

Answer 141

controlling the way manure decomposes to reduce CH4 emissions. Storing manure in anaerobic containers and capturing CH4 as a source of renewable energy

Answer 142

until recently, the only significant international agreement to tackle climate change has been the Kyoto Protocol (1997). Under this, most rich countries agreed to legally binding reductions in their CO2 emissions, though controversially, developing countries, and some of the biggest polluters (China and India) were exempted. Also, several rich countries, notably the USA and Australia, refused to ratify the treaty. This expired in 2012 Then, the Paris Agreement, with implementation from 2020, aims to reduce global CO2 emissions below 60% of 2010 levels by 2050, and keep global warming below 2C, but ideally by 1.5C. However, countries will set their own voluntary targets. These are not legally binding and a timetable for implementing them has yet to be agreed. Meanwhile, rich countries will transfer significant funds and tech to assist poorer countries to achieve their targets. Major CO2 emitters such as China and India argue that global reductions in CO2 emissions are the responsibility of rich countries bc: - countries such as China and India are still relatively poor and industrialisation, based on fossil fuels energy, is essential to raise living standards to levels comparable with those in the developed world - historically, Eu and Na through their own industrialisation and economic development are largely to blame for contemporary warming and climate change

Answer 143

cap and trade offers an alternative, international market-based approach to limit CO2 emissions. Under this scheme businesses are allocated an annual quota for their CO2 emissions if they emit less than their quota they receive carbon credits which can be traded on international markets. Business that exceed their quotas must purchase additional credits or incur financial penalties carbon offsets are credits awarded to countries and companies for schemes such as afforestation, renewable energy and wetland restoration. They can be bought to compensate for excessive emissions elsewhere

Answer 144

UN and World Bank, together with other organisations and govs, fund programmes to protect tropical rainforests, eg UN's REDD programme and World Bank's FCPF fund over 50 partner countries brazil has received support from UN, WB, WWF and the German Development Bank to protect its forests. The ARPA programme now covers nearly 128 million acres of the Amazon Basin, with a target of 150 million acres. Areas included in the programme are strictly protected and there was a 75% decrease in deforestation rates between 2000 and 2012 the benefits include stabilising regional water cycle; offsetting 1.4 billion tonnes of carbon a year; supporting indigenous forest communities; promoting ecotourism; and protecting the genetic bank provided by thousands of plant species in the forests

Answer 145

agriculture is by far the biggest consumer of water, globally accounts for 70% of water withdrawals and 90% of consumption. Wastage of water occurs through the evaporation and seepage through inefficient water management. Improved management techniques which minimise water losses to evaporation include mulching, zero soil disturbance and drip irrigation. Losses to run off on slopes can be reduced by teracing, contour ploughing and the insertion of vegetative strips meanwhile, better water harvesting with storage in ponds and reservoirs, provides farmers with extra water resources. Recovery and recycling of waste water from agriculture, industry and urban populations is technically feasible, but is yet little used outside the developed world in semi-arid regions of water scarcity, eg Lower Indus Valley in Pakistan and US Colorado Basin, water agreements divide resources between downstream states. In Pakistan, the Punjab and Sindh receive 92% of the Indus' flow, and in the Colorado Basin water resources are allocated to California, Arizona, Nevada, Utah and New Mexico. In both regions, the vast bulk of water is used for irrigation

Answer 146

in the Colorado Basin in the southwest USA, surface supplies have diminished as more water is abstracted from rivers, and huge amounts are evaporated from reservoirs like Lake Mead and Lake Powell

Answer 147

the quality of fresh water sources has declined. Over pumping of aquifers in the coastal regions of Bangladesh has led to incursions of salt water, often making the water unfit for irrigation and drinking

Answer 148

Compared to natural ecosystems, human activities such as deforestation and urbanisation reduce evapot and therefore precip; increase surface run off; decrease throughflow; and lower water tables. In Amazonia, forest trees are a key component of the water cycle, transferring water to the atmosphere by evapot, which is then returned through precip. In places, extensive deforestation has broken this cycle, causing climates to dry out and preventing regeneration of the rainforest

Answer 149

exploitation of coal, oil and natural gas has removed billions of tonnes of carbon from geological store - a process that has gathered momentum in the past 30 years with the rapid industrialisation of the Chinese and Indian economies Currently around 8 billion tonnes of carbon a year are transferred to the atmosphere by burning fossil fuels.

Answer 150

land use change (mainly deforestation) transfers approximately 1 billion tonnes of carbon to the atmosphere annually. The additional carbon is stored primarily as atmospheric CO2, where its concentration increases year-by-year. Around 2.5 million tonnes is absorbed by the biosphere, and a similar amount by the biosphere

Answer 151

deforestation means carbon stored in biosphere has declined steeply.

Answer 152

soil is another important carbon store which is being degraded by erosion caused by deforestation and agricultural mismanagement. Carbon stores in wetlands, drained for cultivation and urban development, have also been depleted as they dry out and are oxidised

Answer 153

wetlands include freshwater marshes, salt marshes, peatlands, floodplains and mangroves. their common feature is a water table at or near the surface causing the ground to be permanently saturated

Answer 154

in the lower 48 US states the wetland area has halved since 1600. The destruction of wetlands transfers huge amounts of stored CO2 and CH4 to the atmosphere

Answer 155

in the twentieth century, Canada’s prairie provinces lost 70% of their wetlands. Restoration programmes in this area have shown that wetlands can store on average 3.25 C/ha/year. Now 112,000 ha have been targeted for restoration in the Canadian prairies which should eventually sequester 364,000 tonnes C/year

Answer 156

the need for protection of wetlands as wildlife habitats as well as carbon stores is reflected in management initiatives such as the International Convention on Wetlands (Ramsar) and European Union Habitats Directive restoration focuses on raising local water tables to re-create waterlogged conditions. Eg wetlands on floodplains can be reconnected to rivers by the removal of flood embankments and controlled floods. Coastal areas of reclaimed marshland used for farming can be restored by breaching sea defences elsewhere water levels can be maintained at artificially high levels by diverting or blocking drainage ditches and installing sluice gates

Answer 157

it involves planting trees in deforested areas or in areas that have never been forested because trees are carbon sinks, afforestation can help reduce atmospheric Co2 levels in the medium to long term and combat climate change. It also has other benefits such as reducing flood risks and soil erosion, and increasing biodiversity

Answer 158

the UN’s Reducing Emissions from Deforestation and Forest Degradation (REDD) scheme incentivises developing countries to conserve their rainforests by placing a monetary value on forest conservation. Several projects are already well established such as those in Amazonia (Puras, Russas-Valparaiso) and the Lower Mississippi

Answer 159

In China a massive government-sponsored afforestation project began in 1978. It aims to afforest 400,000km2 by 2050. In the decade 2000-09, 30,000km2 were successfully planted with non-native, fast-growing species such as poplar and birch. However, the project has a wider purpose: to combat desertification and land degradation in the vast semi-arid expanses of northern China

Answer 160

the management of water resources is most effective at the drainage basin scale. At this scale it is feasible to adopt an integrated or holistic management approach to accommodate the often conflicting demands of different water users specific targets for drainage basin planning include run off, surface water storage and groundwater. Rapid run off is controlled by reforestation programmes in upland catchments, reducing artificial drainage and extending permeable surfaces eg gardens, green roofs in urban areas surface water storage is improved by conserving and restoring wetlands, including temporary storage in floodplains. Groundwater levels are maintained by limiting abstraction and by artificial recharge, where wate is injected into aquifers through boreholes

Answer 161

in england and wales drainage basin management is well advanced Under the EU’s Water Directive Framework, ten river basin districts have been defined. The districts comprise major catchments, such as the Severn, Thames and Humber. Each district has its own River Basin Management Plan published jointly by the Environment Agency and Defra. The plan sets targets in relation to, for example, water quality, abstraction rates, groundwater levels, flood control, floodplain development and the status of habitats and wildlife