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CARBON + WATER CYCLES (Dynamic Equilibrium (Background (Negative feedback…

- - - - Water Cycle In a drainage basin, heavy rainfall will increase the amount of water stored in aquifers, which will raise the water table, increasing flow from springs until the water table reverts to normal levels -
      - C Cycle Burning fossil fuels increases atmospheric CO2, but also stimulates photosynthesis - this will remove excess CO2 from atmosphere and restore equilibrium
  - - - Conversion of landuse from rural to urban
      - Artificial surfaces are largely impermeable = little/no infiltration = minimal water storage capacity to buffer runoff
      - Drainage systems remove surface water rapidly
        
        Pitched roofs, gutters, sewage systems
      - High proportion of water from precipitation flows quickly into streams and rivers = rapid rise in water level
        
        This is bc of the drainage systems and impermeabl surfaces
      - Floodplains
        
        Are natural water storage areas
        
        Urban development on floodplains reduces water storage capacity in drainage basins = increased river flow and flood risks
    - - Changes veg. + soils in the C cycle
        
        Ploughing and exposure of soil organic matter to oxidation reduces soil C storage
        
        Harvesting crops with only small amounts of organic matter returned to soils = further loss of C
        
        Erosion by wind and water is most severe when crops have been lifted and soils have little protective cover
        
        Changes to C cycle are less apparent on pasture land or where farming replaces natural grassland
        
        In N America, the NPP of annual crops on the Great Plains exceeds that of the original Prairie grasslands
        
        But C exchanges thru photosynthesis are generally lower than in natural ecosystems
        
        Lack of BD in farmed systems
        
        Growth cycle of crops is often compressed into 4-5 months
        
        Deforestation for farming reduces C storage in the above- and below-ground biomass
      - Modifies the natural water cycle
        
        Crop irrigation diverts surface water from rivers and groundwater to cultivated land
        
        Some irrigation water is extracted by crops from soil storage and released by transpiration; but most is lost to evaporation and in soil drainage
        
        Interception of rainfall is less than in forests and grassland ecosystems
        
        Transpiration and evaporation from leaf surfaces is reduced
        
        Ploughing increases evaporation and soil moisture loss
        
        Furrows ploughed downslope act as drainage channels, accelerating runoff and soil erosion
        
        Infiltration due to ploughing is usually greater in farming systems
        
        Artificial underdrainage increases the rate of water transfer to streams + rivers
        
        Surface runoff increases where heavy machinery compacts soils
        
        Peak flows on streams draining farmland are generally higher than in natural ecosystems
    - - Changes to water cycle
        
        Higher rates of rainfall interception in plantations in natural forests
        
        In E Eng, interception rates for Sitka spruce are as high as 60%
        
        In upland Britian, interception rates are about 30% bc temps. and evap. are lower
        
        Preferred plantation species in UK are conifers
        
        Their needle-like structure, evergreen habit and high density of planting = high interception rates
        
        Increased evaporation
        
        A large proportion of intercepted rainfall is stored on leaf surfaces and is evaporated directly to the atmosphere
        
        Reduced runoff and stream discharge
        
        High interception + evaporation rates + absorption of water by tree roots = alteration of drainage basin hydrology
        
        Streams draining plantations typically have long lag times, low peak flows and low total discharge
        
        Conifer plantations in upland catchments is often to reduce water yield for public supply
        
        Transpiration rates are increased compared to farmland and moorland
        
        Clear felling to harvest timber = sudden but temp. changes to local water cycle
        
        Increases runoff
        
        Reduces evapotransp.
        
        Increases stream driange
      - Changes to C cycle
        
        Changing land use to forestry increases C stores
        
        Mature trees in a typical UK plantation contain 170-200 tonnes C/ha
        
        *10 higher than grassland
        
        *20 higher than ehathland
        
        Soil represents a huge C store
        
        England measurements of forest soil C are around 500 tonnes C/ha
        
        Forest trees extract CO2 from atmosphere and sequester it for hundreds of years
        
        Forest trees only become an active carbon sink (absorbing more C than they release) for the first 100 years after planting
        
        After, the amount of C captured levels off and is balanced by inputs of litter to the soil, the release of CO2 in respiration, and the activities of soil decomposers
        
        So forestry plantations usually have a rotation period of 80-100 years
        
        After this time the trees are felled and reforestation begins afresh
  - - - River Kennet, S England drains an area of 1,200 km2 in Wiltshire and Berkshire
      - The upper catchments mainly comprises chalk - highly permeable
        
        So groundwater contributes most of the the Kennet's flow
      - Chalk stream - so river supports a diverse range of habitats and wildlife: native fauna, Atlantic salmon, brown trout, water voles
      - Within and near the catchment, several urban areas rely on the Kennet basin to meet public supply
        
        Swindon is the largest - pop. over 200,000
        
        Also supplies water for local industries + agriculture
        
        Thames Water abstracts groundwater form the upper catchments from boreholes
        
        None of this water is returned to the river as waste water
      - Impact of water extraction on the regional water cycle:
        
        Rates of groundwater extraction have exceeded recharge rates, and the falling water table has reduced flows by 10-14%
        
        Flows fell by 20% during the 2003 drought
        
        Lower flows = reduced flooding and temp. areas of standing water and wetlands on the floodplain
        
        Lower groundwater levels = dried up springs + seepages, and reduced incidence of saturated overland flow on the chalk
  - - - Permeable/porous water-bearing rocks e.g. chalk
      - Where groundwater is abstracted for public supply by wells and boreholes
      - Groundwater feeds rivers and makes a major contribution to their base flow
      - Water table = upper surface of saturation of the aquifer
        
        Height fluctuates seasonally and is also affected by periods of exceptional rainfall, drought and abstraction
        
        In S Eng.,water table falls March-Sep. as rising temps increase evapotranps. losses; recharge resumes in late autumn
    - - When sed. rocks form a syncline/basin-like structure, an aquifer confined between impermeable rock layers may contain groundwater under artesian pressure
      - Artesian aquifer - when the trapped groundwater is tapped by a well/blowhole
      - 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
      - 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
        
        This is an important water source for London
        
        Over-exploitation in 19th + 1st 1/2 of 20th cents. = drastic fall in water table
        
        Declining demand for water by industry in London and reduced rates of abstraction have allowed the water table to recover
        
        Since 1992 the Thames Water has been granted abstraction licenses to slow the rise of the water table which is now stable
        
        Rainwater enters the chalk aquifer where it outcrops on the edge of the basin in the North Downs
        
        Groundwater then flows by gravity thru the chalk towards the centre of the basin
        
        So under natural conditions the wells and boreholes in the London area are under artesian pressure
  - - - Fossil fuels have driven global industrialisation and urbanistion for past 2 centuries
      - 2013 - fossil fuels accounted for 87% of global energy consumption
      - Fossil fuel consumption releases 10 billion tonnes of CO2 into the atmosphere annually
        
        Increases atmospheric concentration by over 1 ppm
      - CO2 concs. are 400 ppm today; were 280 ppm in 1750
        
        This is bc of the 879 GT of anthropogenic CO2 emissions that have remained in the atmosphere
      - Anthropogenic C emissions comprise under 10% of the natural influx from biosphere and oceans to atmosphere
        
        But they impact significantly on the size of the atmosphere, ocean and biosphere C stores
      - Without increased absorption of anthropogenic C by the oceans and biosphere, today's atmosphere concs. would exceed 500 ppm
    - - C capture + storage (CCS)
        
        To release of C into atmosphere from combustion of fossil fuels is to capture and store CO2 released by power plants and industry
        
        This new tech. has been piloted at only a few coal-fired power stations
        
        1, CO2 is separated from power station emissions
        
        CO2 is compressed and transported by pipeline to storage areas
        
        CO2 is injected into porous rockd deep underground where it is stored permanently
        
        In USA, 40% of all CO2 emissions are from coal- + gas-fired power stations
        
        CCS could reduce these emissions by 80-90%
        
        It effectiveness is limited by economic and geological factors:
        
        Involves large capital costs
        
        Uses large amounts of energy - 20% of a power plant's output is needed to separate the CO2 and compress it
        
        Requires storage reservoirs with specific geological conditions e.g. porous rocks overlain by impermeable strata
  - - - Is an automatic response to changes which disturb a system's balance/equilibrium
      - Change in natural systems can produce either a negative or positive feedback loop
      - Positive feedback
        
        Initial change = further change
      - Negative feedback
        
        Counters system change and restores the equilibrium
    - - Rising temps. + water vapour
        
        Evaporation increases and the atmosphere holds more water vapour
        
        Increased clouds cover and more precipitation
        
        Positive feedback effect
        
        Bc water vapour is a greenhosue gas, more vapour increases absorption of long-wave length radiation = further increase in temp.
        
        Negative feedback effect
        
        More vapour = greater cloud cover which reflects more solar radiation back into space = smaller amounts of solar radiation absorbed by earth
      - Drainage Basins
        
        Inputs and outputs are in equilibrium in LT
        
        Precip. is the main input and it is balanced by outputs of evapotranps. and runoff
        
        But this balance varies from year to year
        
        Its system responds to above average precip. by increasing river flow and evap.; and excess water recharges aquifers, increasing water storage in permeable rocks
        
        Both responses are negative feedbacks
        
        In droughts, evapotransp. and runoff are reduced; springs and seepages dry up as water table falls to conserve groundwater stores
      - Trees
        
        Precip. is sufficient most years to satisfy a tree's demand for water
        
        In drought, shallow-rooted trees (silver birch) become stressed - water lost in transp. is not replaced by a sim. uptake form water in soil
        
        The tree reduces transp. rates by shedding some/all its leaves - this negative feedback loop restores the water balance
    - - Disequilibrium
        
        This is its current state
        
        Human activity (burning fossil fuels) has increased the conc. of CO2 in atmosphere, acidity of oceans and the flux of C between major stores
      - Negative feedback loops
        
        Could neutralise rising levels of CO2 by stimulating photosynthesis
        
        This is Carbon fertilisation
        
        Increased primary production thru C fertilisation is conditional of availability of photosyn. requirements (sunlight, nutrients, nitrogen + water)
        
        So the increase in primary production recently may not be bc of increased atmospheric CO2
        
        Excess CO2 is extracted from atmosphere and stored in the biosphere
        
        Enventually, much of this C would find its way into the LT storage in soils and ocean sediments
      - Positive Feedback Loops
        
        Global warming will intensify the C cycle, quicken decomposition and release more CO2 to the atmosphere = amplified greenhouse effect
        
        Arctic tundra
        
        Global warming is occurring faster than in any other region 1 degree increase in last 30 years
        
        Arctic sea ice and snow cover melt = large expanses of sea and land exposed
        
        = more sunlight absorbed - warms tundra and melts the permafrost
        
        Tundra stores around 16,000 GT of organic C in permafrost
  - - - Monitoring of changes in global air temps., sea surface temps., sea ice thickness and deforestation rates - essential given the potentially damaging impact of climate change
      - Ground-based measurements of environmental change at global scale are impractical
        
        Monioring instead relies heavily on satellite tech. + remote sensing
      - Continuous monitoring by satellites can be different timescales and allows changes/patterns to be observed
        
        The data can be mapped and analysed to show trends + regions of greatest change by GPS
        
        Satellite Techniques
        
        Arctic Sea Ice - NASA's EOS satellites have monitored sea ice growth and retreat since 1978 - Measures microwave energy radiated from E's surface; comparison of time series images to show changes
        
        Ice Caps/Glaciers - Ground-based estimates of mass balance and satellite technology - measures surface height of ice sheet and glaciers via laser technology; shows extent and vol. of ice changes
        
        Surface Sea Temps. - NOAA satellites - measures wave band of radiation emitted from ocean surface; changes in global SSTs + ares of upwelling/downwelling
        
        Water Vapour - NOAA polar orbiters - measures cloud liquid water, total precipitable water etc.; LT trends on cloud cover and water vapour in atmosphere
        
        Deforestation - ESA albedo (reflectivity) images from various satellites - measurements of reflectivity from surface + land use changes
        
        Atmospheric CO2 - NASA's Orbiting Carbon Observatory; ground-based measurements at Mauna Loa, Hawaii, 1958 - new satellite measurements of global atmospheric CO2; also measures effectiveness of absorption of CO2 by plants
        
        Primary Production in Oceans - NASA's MODIS/AQUA - measures NPP in oceans + on land
    - - Water Cycle
        
        Sig. changes occur within a 24-hour period within the water cycle
        
        Lower temps. at night reduce evap. + transp.
        
        Convectional rainfall, dependent on direct heating of the ground surface by the Sun, reaches its oeak during the day
        
        Is v. significant in tropics where the bulk of precip. is from convectional storms
      - Carbon Cycle
        
        Flows of C vary both seasonally and durinally
        
        During the day, C flows from atmosphere to vegetation
        
        At night, C flows form vegetation to atmosphere
        
        The same durinal pattern in plants is observed in phytoplankton
    - - Water Cycle
        
        Higher temps. in summer = more evaportransp. + lower exhaustion of soil moisture + river flows
        
        Seasons are ultimately controlled by variations in the intensity of solar radiation
      - C Cycle
        
        Seasonal variations shown by month-month cahges in NPP of vegetation
        
        In middle and high latitudes, day length/photoperiod and temp; driver seasonal changes in NPP
        
        Similar seasonal variations occur in tropics - but the main cause is water availability
        
        Summer in N hemisphere - trees in full foilage = global net flow of CO2 from atmospheric store to biosphere = atmospheric CO2 levels fall by 2ppm
        
        This flow is reversed when photosynthesis ends and decomposition begins
        
        Seasonal fluctuations are explained by the concentration of continental land masses in N hemisphere
        
        During the growing season, boreal and temperate forests extract large amounts of CO2 from atmosphere - has a global impact
        
        Phytoplankton are stimulated into photosyn. activity by rising water temps., more intense sunlight + lengthening photoperiod
        
        N Atlantic - explosion of microscopic oceanic plant life during summer every year
        
        The resulting algal blooms are visible from space as they're so extensive
    - - Background
        
        Climate has been highly unstable in last million years
        
        Large temp. fluctuations occurring at reg. intervals
        
        4 major glacial cycles in last 400,000 years with cold glacials followed by warmer inter-glacials
        
        Each cycle lasted around 100,000 years
        
        Climatic shifts have had a huge impact on the water + C cycles
      - Water Cycle - Glacial Periods
        
        Net transfer of water from ocean reservoir to storage in ice sheets, glaciers and permafrost during glaciation
        
        Global s.l. falls by 100-130m; ice sheets and glaciers cover 1/3 of continental land mass
        
        As ice sheets advance towards equator they destroy extensive forest and grassland
        
        Area covered by vegetation and water stored in biosphere shrinks
        
        In tropics. climate becomes drier and deserts and grassland displace large areas of rainforest
        
        Lower rates of evapotransp. during glacial phases reduces water exchanges between atmosphere+ oceans, biosphere + soils
        
        This coupled with there being so much freshwater stored as snow and ice, slows the water cycle considerably
      - Carbon Cycle - Glacial Periods
        
        Dramatic reduction in atmospheric CO2
        
        In warmer, inter-glacial periods, CO2 concs. can be 100 ppm higher
        
        No clear explanation for drop in CO2 but there are suggestions:
        
        Excess CO2 could find its way to the deep ocean
        
        Changes in ocean circulation during glacials - brings nutrients to the surface and stimulates phyotplankton growth
        
        Phytoplankton fix large amounts of CO2 by photosyn. before dying and sinking into deep ocean where C is stored
        
        Lower ocean temps. make CO2 more soluble in surface waters
        
        Changes in terrestrial biosphere
        
        Carbon pool in vegetation shrinks during glacials as ice sheets advance and occupy large areas of the continent
        
        During this process, deserts expand, tundra replaces temperate forests and grasslands replace tropical rainforests
        
        With much of the land surface covered by ice, C stored in soils will not longer be exchanged with the atmosphere
        
        Expanses of tundra beyond the ice-limit sequester huge amounts of C in permafrost
        
        Less vegetation, fewer forests, lower temps. and lower precip, NPP and total vol. of C fixed in photosynthesis will declinle
        
        Overall implications are a slowing of the C influx and smaller amounts of CO2 returned to atmosphere thru decomposition
- - - - Atmospheric CO2 has a greenhouse effect
      - CO2 plays a vital role in photosynthesis by terrestrial plants + phytoplankton
      - Plants are imp. C stores + also 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 2 stores
    - - Acidity increases when CO2 exchanges are not in balance (e.g. inputs to oceans from atmosphere exceed outputs)
      - Solubility of CO2 in oceans increases with lower sea surface temps.
      - Atmospheric CO2 levels influence:
        
        Sea surface temps. and ther thermal expansion of the oceans
        
        Air temperatures
        
        Melting of ice sheets and glaciers
        
        Sea level
    - - Water availability influences rates of phtotsyn, NPP, inputs of organic litter to soils and transpiration
      - Water storage capacity of soils increases with organic content
      - Temperatures and rainfall affect decomposition rates and the release of CO2 to the atmosphere
    - - Co2 levels in atmosphere determine intensity of greenhouse gas 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 + CH4
      - Runoff, river flow and evaporation respond to temp. change
  - - - Extensive deforestation in places has broken this cycle = climates dry out + prevents regeneration of the forest
  - - - So the amount of C stored in biosphere and fixed by photosyn. has declined steeply
    - - Acidification of the oceans threatens this vital biological C store + marine life
  - - - Global warming increase evap. rates and therefore the amount of water vapour in the atmosphere
        
        More water vapour (natural GHG) raises global temps. further, increasing evaporation and precipitation - POS. FEEDBACK
      - Increased precip = high runoff + greater flood risks
      - Water vapour is a source of energy in the atmosphere, releasing latent heat on condensation
        
        More energy in atmosphere = extrmem weather events
      - Global warming accelerates the melting of glaciers, ice sheets and permafrost
      - Water storage in cryosphere shrinks, as water is transferred to the oceans and atmopshere
    - - Higher global temps. will generally increase rates of decomposition and accelerate transfers of C from biosphere and soil to the atmosphere
      - In humid tropics, climate change may increase aridity and threaten the extent of forests
        
        As forests are replaced by grassland, the amount of C stored in tropical biomes will diminish
      - In high latitudes, global warming will allow the boreal forests of Siberia, Canada and Alaska to expand polewards
      - C frozen in permafrost of the tundra is being released as temps. rise above freezing and allow oxidation and decomposition of vast peat stores
      - Acidification of the ocean through the absorption of excess CO2 from atmosphere reduces photosynthesis by phytoplankton, limiting the capacity of the oceans to store C
      - LT climate change will see an increase in C stored in the atmosphere, a decrease in biosphere and possibly a similar decrease in ocean carbon stores
      - Movement of C into and out of atmosphere will vary regionally, depending on changes in rates of photosynthesis, decomposition and respiration
  - - - Wetlands include freshwater marshes, salt marshes, petlands, flooplains and mangroves
      - Water table at or near the surface= ground is permanently saturated
      - Ocuupy 6-9% ofEarth's land surface
      - Contain 35% of terrestrial C pool
      - Population growth, economic development and urbanisation = pressure on wetland environments
      - In lower US, the wetland states have halved since 1600
      - Loss of BD + wildlife, + transfers of huge amounts of stored CO2 and methane to atamosphere
      - Climate change has ld to a re-evaluation of wetlands as imp. C sinks
      - Restoration programmes in Canadian prairies (had lost 705 of their wetlands) have shown that wetlands can store 3.25 tonnes C/ha/year
        
        1122 ha have been targeted for restoration - should sequester 364,000 tonnes C/year
      - Protection as wildlife habitats e.g. management initiatives such as the International Convention on Wetlands
      - Restoration focuses on raising water tables and re-recreate waterlogged conditions
      - Wetlands on floodplains can be reconnected to rivers by the removal of flood embankments and controlled floods
      - Coastal areas of recliamed marshland used for farming cna be restored by breaching sea defences
      - Water levels can be maintained at artificially high levels by diverting or blocking drainage ditches and installing sluice gates
    - - Planting trees in deforested areas of areas that have never been forested
      - Tress are C sinks - so afforestation can help reduce atmospheric CO2 levels MT-LT
      - Other benefits = reduced flood risks and soil erosion, increased BD
      - Inexpensive methods = protecting tropical rainforests from loggers, farmers and miners
      - UN's REDD scheme encourages developing countries to conserve their rainforests by placing a monetary value on forest conservation - well-established projects in Amazonia + Lower Mississpipi
      - Massive gov.-sponsored afforestation project in China since 1978
        
        Aims to afforest 400,000 km2 (size of Spain) by 2050
        
        30,000 km 2 planted with non-native, fast-growing species (poplar + birch) 200-09
        
        Wider purpose of project: to combat desertification and land degradation in the semi-arid expanses of N China
    - - Overcultivation, excessive intensification + overgrazing are unsustainable and cause soil erosion and release of large quantities of C into atmosphere
      - Intensive livestock famring produces 100 million tonnes/year of CH4
      - CH4 emissions form flooded (padi) rice fields and from uncontrolled decomposition of manure
      - Land + Crop Management
        
        Zero tillage - growing crops without ploughing the soil - conserves the soil's organic content, reduces oxidation and the risk of erosion
        
        Polyculture - growing annual crops interspersed with trees - trees provide year-round ground cover + protects from erosion
        
        Crop residues - leaving crop residues on fields after harvest to provide ground cover and protection from erosion and drying out
        
        Avoiding use of heavy farm machienry on wet soils which leads to compaction and risk of erosion by runoff
        
        Contour ploughing on slopes to reduces erosion and runoff
        
        New strains of rice that grow in drier conditions and therefore produce less CH4 + chemicals (e.g. ammonium sulphate) which stops microbial activities that produce CH4
      - Livestock Management
        
        Improving quality of animal feed to reduce enteric fermentation so that less feed is converted to CH4; mixing methane inhibitors with livestock feed
      - Manure Management
        
        Controlling the way manure decomposes to reduce CH4 emissions
        
        Storing manure in anaerobic containers and capturing CH4 as a source of renewable energy
    - - Some of the world's largest greenhouse has emitters have opted to pursue narrow self-interest for political and economic reasons
      - 1997 Kyoto Protocol
        
        Most rich countries agreed to legally binding reductions in their CO2 emissions
        
        Some of the biggest polluters (e.g. China) and developing countries were exempted
        
        Several rich countries (USA + Australia) refused to ratify the treaty
        
        Expired in 2012
      - Paris Climate Convention 2015
        
        New international agreement reached
        
        For implementation in 2020
        
        Aims to reduce global emissions by below 60% of 2010 levels by 2050 and keep global warming below 2 degrees
        
        Countries will set their own voluntary targets
        
        These targets are not legally binding and there is not yet a timetable for implementing them
        
        Rich countries will transfer significant funds and technologies to poorer countries to acheive their targets
        
        Major CO2 countries e.g. China and India argue that global reductions in CO2 emissions are the responsibility of rich countries bc:
        
        Countroes such as China and India are still relatively poor and industrialisated, based on fossil fuel energy, is essential to raise living standards to levels comparable with those in the developed world
    - - International-market based approach to limit CO2 emissions
      - Businesses are allocated an annual quota for CO2 emissions
        
        Emitting less than quota = carbon credits that can e traded on international markets
        
        Exceeding quota = must purchase additional credits or incur financial penalities
      - Carbon offsets are credits awarde to countries and companies for schemes e.g. afforestation, renewable energy and wetland restoration
        
        They can be bought to compensate for excessive emissions elsewhere
  - - - Multilateral organisations e.g. UN and WB recognise the importance of forests in he water cycle
      - These multilaterals co-operate with organisations and governments to fund programmes to protect tropical rainforests
      - The UN's Reducing Emissions from Deforestation and Forest Degradation (REDD) scheme and the WB's Forest Carbon Partnership Facility fund over 50 partner countries in Africa, Asia-Pacific and South America
      - Financial incentives to protect forests include C offsets and direct funding
      - Amazon Regional Protected Areas programme
        
        Covers 10% of Amazon basin
        
        Areas included in the programme a strictly protected
        
        Stabilises the regional water cycle
        
        Offsets 430 million tonnes of C a year
        
        Supports indigenous forest communities
        
        Promotes ecotourism
        
        Protects the genetic bank provided by thousands of plant species in the forest
    - - Agriculture is the largest consumer - accounts for 70% of global water withdrawals and 90% of consumption
      - Water wastage through evaporation and seepage through inefficient water management e.g. over-irrigating crops
        
        Management techniques
        
        Mulching
        
        Zero soil disturbance
        
        Drip irrigation
      - Managing runoff losses
        
        Terracing on slopes
        
        Contour ploughing
        
        Insertion of vegetative strips
      - Extra water sources for farmers
        
        Better harvesting
        
        Storage in ponds and reservoirs
      - Recovery and recycling of waste water is feasible, but used little outside the developed world
      - Semi-arid regions: Lower Indus Valley, Pakistan + US Colorado Basin
        
        Water agreements divide up resources between downstream states
        
        The Punjab and Sindh in Pakistan receive 92% of the Indus' flow
        
        Water resources from the Colorado Basin are allocated to California, Arizona, Nevada, Utah and New Mexico
        
        The vast bulk of water is used for irrigation in both cases
    - - Management of water resource sis most effective at the drainage basin scale
      - Integrated and holistic management approaches to accommodate conflicting demands of different water users
      - Different water uses
        
        Agriculture
        
        Industry
        
        Domestic use
        
        Wildlife
        
        Recreation and leisure
      - The different water users impact
        
        Water quality
        
        River flow
        
        Groundwater levels
        
        Wildlife habitats
        
        Biodiversity
      - There are specific targest for drainage basin planning
        
        Run-off
        
        Surface water storage
        
        Conserving and restoring wetlands, inc. temporary storage in floodplains
        
        Groundwater
        
        Levels are maintained by limiting abstraction (e.g. for public supply, farming and recharge)
        
        Artificial recharge - water is injected into aquifers through boreholes
      - England ad Wales
        
        Drainage basin management is very advanced
        
        10 river basin districts have been defined under the EU's Water Directive Framework
        
        They comprise major catchments
        
        Severn
        
        Thames
        
        Humber
        
        The 10 river districts comprise major catchments
        
        Each district has its own River Basin Management Plan published jointly by the Environment Agency and DEFRA
        
        The plan sets targets in relation to water quality, abstraction rates, groundwater levels, flood control, floodplain development and the status of habitats and wildlife
- - - - 3 main stores
        
        Atmosphere
        
        Smallest store
        
        Oceans
        
        Biggest store
        
        Land
      - Main processes between stores
        
        Precipitation
        
        Evapotranspiration
        
        Runoff
        
        Groundwater flow
    - - LT storage in sed. rocks holds 99.9% of all C on Earth
      - Most of C in circulation moves rapidly between:
        
        Atmosphere
        
        Oceans
        
        Soil
        
        Biospehre
      - Main pathways
        
        Photosynthesis
        
        Respiration
        
        Oxidation (decomposition + combustion)
        
        Weathering