water and carbon cycles . Flashcards
(32 cards)
what are systems composed of ?
inputs - where energy or matter is added to the system
outputs - where energy or matter leaves the system
stores - where matter or energy builds up in a system
flows - where matter or energy moves in a system
boundaries - limits to the system ( eg. watershed )
what is dynamic equilibrium ?
when inputs equal outputs despite changing conditions
what is positive feedback ?
occurs when a chain of effects amplifies the impacts of the original event, leading to dynamic equilibrium
what is negative feedback ?
a chain of events the nullifies the impacts of the original event , leading to dynamic equilibrium
what are the inputs and outputs on a local drainage basin system ( local scale water cycle ) ?
inputs = precipitation
outputs = evapotranspiration ( from plants ), streamflow ( water flowing through streams into oceans and tributaries )
what are stores of a local drainage basin system ?
grounds water, soil water, rivers, interception, surface
what are flows in a local drainage basin system ?
infiltration, percolation, throughflow, surface runoff, groundwater flow, streamflow, stemflow
what is water balance ?
used to express the process of water storage and transfer in a drainage basin
calculated by : precipitation = total runoff + evapotranspiration +/- storage
what impacts the water cycle on a local scale ?
deforestation = less interception, soils less able to store water
storm events = increases runoff and water storage
seasonal changes = more interception in spring, snow reduces flows and hot weather reduces precipitation
agriculture - pastoral ground tramples so less infiltration, ploughing increases infiltration, ditches increase runoff
urbanisation = impermeable surfaces increase runoff
what is the soil water budget and how does it change throughout the year ?
shows the balance of inputs and outputs inn the water cycle and shows how inputs and outputs impact soil water storage and availability
there is a surplus of water in winter after recharge of soil water in autumn because there is more precipitation than evapotranspiration ( inputs exceed outputs )
in summer there can be a deficit of soil water as outputs exceed inputs
what is field capacity ?
maximum storage of water in soil
what does the water budget depend on ?
type, depth and permeability of soil and bedrock
what are the four areas water can be stored ?
hydrosphere - liquid water
lithosphere - stored in crust and upper mantle
cryosphere - frozen
atmosphere - water vapour
what are other ways water can be stored ?
aquifers - underground water stores, unevenly distributed worldwide. shallow groundwater aquifers can store water up to 20 years but deeper fossil aquifers may last up to 10,000 years
glaciers - store water 20-100 years
lakes - store wate 50- 100 years
seasonal snow cover and rivers - 2-6 months
soil water - 1-2 months
how does the water cycle change over time due to farming practices ?
ploughing breaks up the surface increasing infiltration, arable farming(crops) can increase interception and evapotranspiration, pastoral farming(animals) compacts the soil reducing infiltration and increasing runoff
how does the water cycle change over time through natural processes ?
in summer higher temperature = less precipitation, more evaporation, increased evapotranspiration(deciduous trees have leaves + high temp)
in winter = reduced flows as water stored as ice, reduced interception when deciduous trees loose leaves
how does the water cycle change over time due to land use change ?
deforestation reduces interception, evapotranspiration but infiltration increases as land is clear
construction reduces infiltration and evapotranspiration but increases runoff
how does the water cycle change over time due to water abstraction ?
volume of water in surface stores decreases
water abstraction increases in dry seasons as human demand is higher
water abstracted is often more than water inputted into aquifers = decline in global long term stores
what is a flood hydrograph ?
used to represent rainfall for the drainage basin of a river and the discharge of the same river on a graph
what are the two types of flood hydrogaphs ?
flashy = short lag time , steep rising and falling limb, higher flood risk , high peak discharge
subdued = long lag time, gradually rising and falling limb ,lower flood risk , lower peak discharge
what would cause a flashy flood hydrograph ?
pastoral farming = ground trampled and compacted so less interception
deforestation = less interception
high rainfall intensity = higher discharge potential
antecedent rainfall = ground is saturated meaning increased surface runoff
impermeable underlying geology = decreased infiltration
high drainage density = many tributaries to the main river
what are transfers of carbon on a local scale ?
photosynthesis - living organisms covert co2 into oxygen and glycose using light, they are sequestering carbon
respiration = releasing co2 and water from glucose and oxygen
plants are net carbon absorbers and net oxygen producers
decomposition, combustion
what are the stores of carbon on the global scale ?
marine sediments and sedimentary rocks (lithosphere) - long term
oceans (hydrosphere) - dynamic
fossil fuel deposits (lithosphere) - long term but currently dynamic
soil organic matter (lithosphere) - mid term
atmosphere - dynamic
terrestrial plants ( biosphere) - mid term but very dynamic
how does the carbon cycle change over time with natural processes ?
wildfires: transfer carbon from biosphere to atmosphere as co2 is released in burning, can encourage growth of plants in the long term
volcanic activity: carbon stored within the earth is released during volcanic eruptions
