Water notes
Where is the Earth’s water?
Globally –
The majority of the Earth’s water is stored in the Oceans (96.5%) and the rest is stored at freshwater or
saline water.
,Freshwater –
Although only a small amount of water is stored as freshwater (2.5%), the majority of freshwater can be
found in ice caps and glaciers (68.7%) or as groundwater. Therefore, very little freshwater is stored on
the surface.
Surface water –
Surface water is freshwater, however there is only 1.2% available and of this percentage, most of it is
stored as ground ice (69%) or in lakes (20%).
What are the implications for people?
Since only 2.5% of water stored globally is freshwater, there is only a small proportion available for
everyone. Therefore, it is important that water is not wasted, so it can be conserved for future
generations.
Hydrological Cycle
, Evaporation – when liquid water is turned into water vapour. A large amount of energy is needed for
this, which is usually provided for by the sun or the movement of wind.
Condensation – water which collects as droplets on a cold surface when coming into contact with humid
air.
Precipitation – this is when water in any form falls from the atmosphere to the surface of the earth.
This includes rain, hail, sleet or snow.
Evapotranspiration – the amount of water removed by evaporation from a vegetated surface of land.
Transpiration – process by which water is lost from a plant through stomata in the leaves.
Interception – when raindrops are prevented from falling onto the soil surface because they are
intercepted by leaves and branches.
Stemflow – water which runs down the stems and braches of plants.
Surface run-off – when water flows out of the drainage basin and enters the river.
Surface Storage – the total volume of water held by the Earth’s surface in lakes, ponds and puddles.
Infiltration – this is when water is absorbed by the soil. When the soil is dry, infiltration rates are rapid,
unlike when the soil is moist, they are at their lowest.
Throughflow – when water moves through the subsoil layer by gravity.
Soil moisture storage – refers to the amount of water held in the soil at any particular time.
Percolation – the downward movement of water in rock under the soil layer. The rate of percolation
depends on how permeable the rock is. If it is permeable, the rate will be at its highest in comparison to
non-impermeable rock, where it will be at its lowest.
Groundwater flow – this is the slowest transfer of water within the drainage basin but provides the
main input of water into the river during dry seasons. This happens through bands of sedimentary rock.
Water table – the level below which the ground is saturated with water.
Aquifer – a body of permeable rock which can contain or transmit groundwater.
Where is the Earth’s water?
Globally –
The majority of the Earth’s water is stored in the Oceans (96.5%) and the rest is stored at freshwater or
saline water.
,Freshwater –
Although only a small amount of water is stored as freshwater (2.5%), the majority of freshwater can be
found in ice caps and glaciers (68.7%) or as groundwater. Therefore, very little freshwater is stored on
the surface.
Surface water –
Surface water is freshwater, however there is only 1.2% available and of this percentage, most of it is
stored as ground ice (69%) or in lakes (20%).
What are the implications for people?
Since only 2.5% of water stored globally is freshwater, there is only a small proportion available for
everyone. Therefore, it is important that water is not wasted, so it can be conserved for future
generations.
Hydrological Cycle
, Evaporation – when liquid water is turned into water vapour. A large amount of energy is needed for
this, which is usually provided for by the sun or the movement of wind.
Condensation – water which collects as droplets on a cold surface when coming into contact with humid
air.
Precipitation – this is when water in any form falls from the atmosphere to the surface of the earth.
This includes rain, hail, sleet or snow.
Evapotranspiration – the amount of water removed by evaporation from a vegetated surface of land.
Transpiration – process by which water is lost from a plant through stomata in the leaves.
Interception – when raindrops are prevented from falling onto the soil surface because they are
intercepted by leaves and branches.
Stemflow – water which runs down the stems and braches of plants.
Surface run-off – when water flows out of the drainage basin and enters the river.
Surface Storage – the total volume of water held by the Earth’s surface in lakes, ponds and puddles.
Infiltration – this is when water is absorbed by the soil. When the soil is dry, infiltration rates are rapid,
unlike when the soil is moist, they are at their lowest.
Throughflow – when water moves through the subsoil layer by gravity.
Soil moisture storage – refers to the amount of water held in the soil at any particular time.
Percolation – the downward movement of water in rock under the soil layer. The rate of percolation
depends on how permeable the rock is. If it is permeable, the rate will be at its highest in comparison to
non-impermeable rock, where it will be at its lowest.
Groundwater flow – this is the slowest transfer of water within the drainage basin but provides the
main input of water into the river during dry seasons. This happens through bands of sedimentary rock.
Water table – the level below which the ground is saturated with water.
Aquifer – a body of permeable rock which can contain or transmit groundwater.
