A2 Geography Unit 3 Water and Carbon Cycles

cryosphere

areas of earth where water is frozen

milankovitch cycles

100,000 years elliptical/spherical orbit, axis tilts and wobbles

el nino vs la nina

hot vs cold

watershed

drainage divide between basins

types of flows

throughflow, throughfall, stem flow, infiltration, groundwater flow, overland flow, percolation

throughflow

lateral movement through soil, pore spaces fissures and root pipes and animal burrows

throughfall

interception

infiltration

 water enters soil

groundwater flow

vertical and lateral movement through underlying rock due to gravity and pressure

overland flow

surface runoff, saturation excess or infiltration excess

percolation

water from soil into bedrock

water table

permanently saturated level of drainage basin

stores of water

soil moisture, interception, vegetation, surface, groundwater, channel

examples of adaptations

tropical rainforests have drip tips, coniferous forests have sloping branches for snow

aquifer

underground permeable rock/material holding freshwater but quality decreases with depth

hygroscopic water

water in thin films by molecular attraction to the surface of soil particles

capillary water

thicker films occupy small pore spaces in the soil held together by gravity and surface tensions

gravitational water

excess water occupies all large and free-draining spaces, drains away after rain stops falling

field capacity

total water remaining in a freely drained soil after all gravity water drained away

wilting point

insufficient soil water to compensate for plant water losses from transpiration

river regimes

indicate annual variation of discharge and result from impact of climate geology and soils

colorado river basin case study

25 tributaries, upper has arid conditions, lower has longer growing season with temps of 40 degrees and prone to flash flooding seasonal rainfall, rise in summer months due to rocky mountains snowmelt, early 1900’s discharge was 13x higher in summer than in winter

what is preceding discharge

rate of flow prior to latest storm event

drainage density

a measure of length of channel and tributaries per unit area

factors of river regimes

rock type, slope, area, shape, drainage density, land use, soil, vegetation, human intervention, deforestation

flooding in wales stats

expected annual damages at 200 mil, 220,000 properties at risk

bangladesh floods

2007, over 2000 dead across south asia, 2.2m acres of cropland damaged, rice jute and sugar, main highways destroyed, brahmaputra and ganges rivers flooded at the same time, 75% of country below 10m above sea level

solutions of bangladesh floods

flood action plan - embankments along coasts and rivers, unicef provided vaccinations and hygiene kits, bangladesh rice research institute introduced flood resistant rice varieties

causes of bangladesh 2007 floods

abnormal rainfall, most water comes from outside bangladesh so little control, deforestation in himalaya, snow melt and relief rainfall

amount of water available in south east england vs sudan

58,000 gallons vs 269,000 gallons per person

define drought

severe lack of water in a given area over an extended period of time (3 months or longer) compared to the expected average

human factors of drought

aquifer depletion, climate change, deforestation causes reduced atmospheric moisture and soil ability to hold water, agriculture and building dams

physical factors of drought

reduced stream flow, sea surface temp, high pressure systems block movement of low pressure systems

aral sea case study

kazakhstan and uzbekistan, 68,000 km squared, only covers 10% of original area, soviet diversion schemes in 1960s, water taken for cotton and fruit irrigation

1976 drought

above 32 degrees for 7 consecutive days, no rain for 45 days in some parts of sw england, jet stream further north than usual so high pressure sat over uk, october had 30-70 % above normal rainfall

somerset levels causes

prolonged storms, high tides, lack of dredging, maise replaced grasland so more surface run-off

impacts of somerset levels

600 homes evacuated, villages cut off, over 10 mil damage, tourism industry lost 200 mil, 900 litres of fuel stolen from pumping station, insurance rose, over 2 years to restore soil damage and grow crops again

responses to somerset levels

patrol rescue boats and police, army sandbags and food, somerset levels and moors action plan, total of 100 mil over 20 year plan

peat

partially decomposed matter that has accumulated in waterlogged conditions

different amounts of carbon storage

over 40,000gt in ocean, 600gt in sea floor sediments, 100,000,000gt in rocks, 2300 in soil

time for carbon to stay in stores

25 years for surface ocean, 1000 for deep ocean, 150 mil years for rocks and fossil fuels

define carbon sequestration

natural capture and storage of co2 by physical or biological processes

NPP

net primary productivity, rate of organic matter production, highest in rainforest and marsh

how much global energy consumption is from fossil fuels

85%

atmosphere-land carbon pathway

carbon into plants via photosynthesis, some stored, into ground through stems fallen leaves and decomposition, into soil carbon stores, into atmosphere via decomposition and respiration,

physical pump for ocean carbon pathway

concentration gradient causes carbon to diffuse into oceans, transferred to deep ocean areas where cold dense surface water sinks, depends on acidity of water and amount of carbon already present

biological pump for ocean carbon pathway

phytoplankton in euphotic zone photosynthesise taking in co2, taken up food chain to deep consumers and eventually reach the sea floor, dead organisms sink, shells too

slow carbon pathway involving tectonics

carbon carried to oceans via throughflow, surface runoff, rain and rivers, ocean carbon sedimentation, metamorphism of rocks, co2 carried by asthenosphere flow, some released at mid ocean ridges, melting of plates leads to co2 being released through volcanoes

carbonation

rainwater collects in pools and dissolves co2, also through groundwater movement and overland flow, breaks down rock containing lime and produces bicarbonate (soluble)

air uplift

air rises to saturation point, fall in pressure due to altitude so less collisions and less heat

convectional rainfall is also known as

adiabatic cooling

convectional rainfall

land heats up air above it, thermals rise and cool, ability to hold water vapour decreases

orographic rainfall

forced to rise over a barrier like a mountain, leeward slope has little rain aka rain shadow effect

frontal rainfall

warm air forced over cold dense air so cumulus clouds formed

advection cooling

warm moist air is cooled as it crosses over cooler sea or land surface aka mist

radiation cooling

ground loses heat when skies clear at night so air directly above cools forming dew and fog

feeder seeder

water droplets from high clouds fall through and clouds collect more water

bergeron findeisen process

clouds contain ice crystals which grow and fracture forming little pieces with big surface area attracting more water droplets creating dense particles which fall faste

the collision process

condensation nuclei like large sea salt particles form seeds for water droplets to form, larger ones combine with smaller ones as they have larger weight and velocity

facts on carbon rainforest storage

700 tonnes/hectare, 550 Gt stored, large biomass little soil or litter, rapid leeching occurs, up to 3000mm annual rainfall, humus = black substance in soil remaining after most organic litter decomposed

temperate grassland carbon storage facts

2-10 tonnes/hectare above ground, 100-200 below ground, 185 Gt stored, eg north american prairies, large soil storage little biomass or litter, seasonal variations in temp and only 500mm rainfall at most, turf grasses and bunch grasses adapted to drought, fire, wind and cold, 

deforestation impact on carbon storage facts

between 1970 and 2013 rates at 17,500 square km a year, rainforests at 180 tonnes/hectare soya crop only 2.7

afforestation impacts on carbon storage facts

monoculture of trees can replace grassland but cant store as much as natural forests, REDD U'N’s reducing emissions from deforestation and forest degradation puts monetary value on conservation

negative agriculture impacts on carbon storage facts

loss of SOC, soil erosion problems and potentially lasting damage, soil disturbance causes rates of decomposition to speed up, overgrazing reduces plant cover and roots, fertilisers increase decomposition

positive impacts of agriculture on carbon storage facts

manure and recycled plant remains increase SOC, introducing earthworms, cover crops inbetween harvests, mixing trees with livestock

peat facts

3% of earths surface, up to 600 Gt globally, formed by sphagnum mosses, rushes, sedges, and bracken, up to 3000 tonnes/hectare

types of peatland

fen - groundwater meets surface, blanket - hilltops, raised bogs - valley bottoms saturated 

managing peat bogs facts

extracting peat is 10% of human co2 emissions, compost, fertiliser and rural fuel source, drained for farming, moorland burning encourages growth of heather but destroyes sphagnum

untouched vs touched peatlands facts

untouched takes in 4.1 tonnes a year, touched puts out 22.4 tonnes per hectare in england

restoration of peatlands

replanting, rewetting drained peatlands, eg yorkshire southern pennines, gullys blocked with stone dams, water table raised, seed and fertiliser dropped using helicopters

increase of carbon statistic with dates

1750 280ppm-420ppm now

that carbon graph

keeling curve, measurements taken offshore mauna loa

impacts of carbon on the water cycle

precipitation, river discharge, acidification of the oceans, sea levels rise

impact of carbon on precipitation

total amount the same but more seasonal, high intensity rainfall caused 3 billion gbp damage in 2007, higher prob of extreme weather events

impacts of carbon on river discharge 

increased risk in winter, infiltration excess runoff rivers return to original levels fast

impact of carbon on acidification of oceans

estimated that 1/3 of co2 released by humans diffuses into the ocean, 30% increase in acidity since 1750, carbonic acid produced reacts with carbonate ions so none left for coral productions = thinner shells

impacts of carbon on sea level rise

thermal expansion, worldwide glacial and permafrost melting, risen 200mm since 1900

eustatic

global

isostatic

regional

local impacts of carbon in atmosphere

more evaporation and drier soil, reduced vegetation means less carbon sequestration and more surface run of and soil erosion, shorter more intense rainfall means drought lasts longer, desertification in the sahel region, fallen leaves in uk washed away by surface runoff carrying carbon as biomass

types of rainfall

convectional or adiabatic cooling orographic frontal advection radiation

negative possible feedback of carbon in atmosphere

higher temps more plant growth, more co2 taken in

cryosphere feedback

ice has albedo of 80%, sea ice begins to melt revealing darker oceans with lower albedo, sea warms melting more ice, more evaporation as oceans warm, more clouds in lower atmosphere with higher albedo so waters cool, ice forms reflecting more radiation

methane feedback

estimated more than double the current volume of carbon in our atmosphere of methane stored in permafrost, positive cycle

terrestrial marine feedback

more water vapour in the atmosphere = higher temps, but more clouds mean more radiation reflection, very unpredictable, warm water less effective at absorbing co2, and the more absorbed the less it can in future, coral reefs damaged so biological carbon pump less effective, global biome patterns changing, more coniferous forest = more carbon storage

impacts of carbon in atmosphere examples eg asia

major rivers fed by seasonal meltwater like himalayan plateau have little source, water security in southeast asia and china threatened with growing population