water and carbon

inputs

energy or matter added to a system

outputs

energy or matter leaving system

stores

where energy or matter builds up

flows

energy or matter moves from one store to another

boundaries

limits of the system

open systems

• energy and matter can enter and leave an open system

• example drainage basins

closed system

• matter can’t enter or leave a closed system

• energy can enter and leave a closed system

• eg carbon cycle

positive feedback

• mechanisms amplify the change in inputs or outputs

• system responds by increasing the effects of change moved further away from previous state

negative feedback

• mechanisms counteract the change in inputs or outputs

• system responds by decreasing the effects of the change keeps it closer to its original state

earth has 5 subsystems

• cryosphere

• biosphere

• lithosphere

• hydrosphere

• atmosphere

cryosphere

includes all the parts of the world where it is cold enough for water to freeze

lithosphere

outermost part of earth and includes the crust and parts of the mantle

biosphere

part of earth where living things are found. includes all the living parts of the earth

hydrosphere

includes all of the water on earth. it may be in liquid ,solid,gas form . it can also be saline or fresh

atmosphere

is the layer of gas between the earths surface and space , held in place by gravity

earths freshwater distribution

• 69% is in cryosphere

• 30% is groundwater

• 0.3% is liquid freshwater

• 0.04% is stored as water vapour

global hydrological cycle

water is constantly cycled between different stores

evaporation

• occurs when water changes state into a gas - water vapour - it gains energy normally from solar radiation increases atmospheric store

• magnitude of evaporation depends on location and season

condensation

• occurs when water vapour changes state to become a liquid - it loses energy to surrondings - it happens when air containing water vapour cools to its dew point

• water droplets can stay in atmosphere or flow to other systems

• magnitude of condensation depends on amount of water vapour in atmosphere and temperature

cloud formation and precipitation

• essential parts of water cycle

• clouds form when warm air cools down,water vapour condenses which causes these water to droplets to form as clouds

• they need cloud condensation nuclei to be able to form

• cloud formation and precipitation can vary seasonally

things that can cause warm air to cool

• other air masses warm air is less dense than cool air . as a result when warm air meets cool air it is forced up above . frontal precipitation

• topography- warm air meets mountains air rises .forces it to cool down . - orographic precipitation

• convection- sun heats up the ground , moisture on the ground evaporates and rises up a column of warm air . as it gets higher it cools. - convective precipitation.

cryospheric processes

• such as ablation and accumulation change water stored as ice

• during periods of global cold inputs are larger than outputs

• variations have different time scales

drainage basins

• can be open local hydrological cycles

• drainage basin is the area surrounding the river where the rain falling onto land flows into river

• boundary of a drainage basin is the watershed

• drainage basins are open systems with inputs and outputs

• water comes into the system as precipitation and leaves via evaporation , transpiration and river discharge

drainage basin inputs

• precipitation

drainage basin stores

• interception

• vegetation storage

• surface storage

• soil storage

• groundwater storage

• channel storage

drainage basin flows

• infiltration

• overland flow

• throughfall

• stemflow

• throughflow

• percolation

• groundwater flow

• baseflow

• interflow

• channel flow

outputs

• evaporation

• transpiration

• evapotranspiration

• river discharge

water balance

• shows balance between inputs and outputs

• in wetter seasons precipitation exceeds evapotranspiration which will create a water surplus

• in drier seasons precipitation is lower than evapotranspiration so ground stores get depleted

• so at the end of dry season there is a deficit of water in ground recharged in the next wet season

hydrographs

• river discharge is measured in cumecs

• peak discharge - this is the highest point on the graph where river discharge is at its greatest

• lag time - delay between peak rainfall and peak discharge

• rising limb - the part of the graph up to peak discharge

• falling limb - this is the part of the graph after peak discharge

factors affecting hydrograph

• size of drainage basin - larger basins catch more precipitation so they have a higher peak discharge than smaller basins

• shape of drainage basin - circular basins are more likely to have a flashy hydrograph than long narrow basins

• ground steepness - water flows more quickly downhill in steep sided drainage basins which shortens lag time

• rock and soil type - impermeable rocks and soils don’t store water or let it infiltrate which increases surface runoff

variation in water cycle due to natural factors

• storms and precipitation - intense storms generate more precipitation and greater peak discharges than light rain showers - the larger input of water causes flows to increase in size

• seasonal changes and vegetation - size of inputs flows and stores in the water cycle varies with the seasons - during the winter season temperatures may cause water to freeze which can reduce the size of flow through drainage basins

• amount of vegetation affects the amount of interception that is occuring

• more vegetation in a drainage basin the more water is lost through evaporation and transpiration