The Water Cycle Flashcards
What is atmospheric water?
Water found in the atmosphere; is mainly water vapour with some liquid water (cloud and rain droplets) and ice crystals.
What is cryospheric water?
The water that is locked up on the earth’s surface as ice.
Hydrosphere meaning?
A discontinuous layer of water at or near the earth’s surface. It includes all liquid and frozen surface waters, groundwater held in soil and rock and atmospheric water vapour.
What is Oceanic water?
The water contained in the Earth’s oceans and seas but not including such inland seas as the Caspian sea.
What is terrestrial water?
This consists of groundwater, soil, moisture, lakes, wetlands and rivers.
The total amount of water in the hydrosphere.
1.338 x 10⁹ km³. It is thought that approximately 97% of this is oceanic water. Freshwater, the remaining 3%, is locked up in ice, glaciers and permafrost (cryospheric water), groundwater, lakes, soil, wetlands, rivers, rivers, biomass (terrestrial water) and atmospheric water.
Average depth of oceanic water.
3,683m.
Oceanic water.
The oceans cover approximately 72% of the planet’s surface, divided into 7 principal oceans and smaller seas. Oceanographers have only explored 5%.
The make up of oceanic water (pH)
It is salty because it contains dissolved salts, these allow the water to stay liquid below 0 degrees. They are alkaline- avg pH of about 8.14. The pH has fallen from approximately 8.25 in the last 250 years and appears to be destined to continue falling. The pH change is linked to the increase in atmospheric carbon and may have a profound influence on marine ecosystems- coral reefs.
The five locations of cryospheric water.
Sea ice- the Ross ice shelf.
Permafrost- the Alaska North slope.
Alpine glaciers- Mer de Glace, France.
Ice sheets- the Greenland ice sheet.
Ice caps- the Iceland ice cap.
Sea ice.
Sea ice does not raise sea level when it melts, because it forms from ocean water. it is closely linked to our ocean’s climate, so scientists are concerned with its recent decline.
Ice shelves.
Platforms of ice form where ice sheets and glaciers move out into the oceans. Mostly exist in Antarctica and Greenland as well as in the arctic near Canada and Alaska.
Icebergs.
Chunks of ice that break off glaciers and ice shelves and drift in the ice. They only raise the sea level when they first leave the land and push into the water, not when they melt.
Ice sheets.
Mass of glacial land ice extending more than 50,000km (squared). Two major ice sheets on Earth today cover most of Greenland and Antarctica. Together, the Antarctic and Greenland are more than 99% of the freshwater ice on Earth.
Ice caps.
They are thick layers of ice on land that are smaller than 50,000km². Often found in mountainous areas. Ice caps tend to be dome-shaped and are centred over the highest point of an upland area. They flow outwards, covering almost everything in their path- the biggest source for man glaciers.
Where- the Himalayas, the Rockies, the Andes, and the Southern Alps of New Zealand.
Alpine glaciers.
Thick masses of ice are found in deep valleys or upland hollows.
Mostly fed by ice caps or smaller corrie glaciers.
These glaciers are particularly important in the Himalayas- 15,000 Himalayan glaciers form a unique reservoir which is the lifeline for millions of people in South Asian countries.
Permafrost.
Ground that remains below 0 degrees for at least two consecutive years. Most of today’s permafrost formed in the Holocene (the last 10,000 years) and during the Ice age.
What four categories does terrestrial water fall into?
-Surface water
-Groundwater
-Soil water
-Biological water
Surface water- Rivers.
Both the storage and transfer of water, are streams of water in a defined channel. Rivers make up 0.0002% of all water.
Surface water- Lakes.
Collections of fresh water found in hollows on the land surface.
Surface water- Wetlands.
Ramsar Convention defines wetlands as ‘areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing where there is a dominance by vegetation.’
Groundwater- lithosphere
Water collects underground in the pore spaces of rock.
Ground water- Soil water.
Held together with air in unsaturated upper weathered layers of the earth.
Ground water- Biological water.
Water is stored in the biomass. It varies widely around the globe depending on the vegetation cover and type.
Condensation.
The process by which water vapour changes to liquid water.
Evaporation.
The process by which liquid water changes to gas.
What does the rate of evaporation depend on?
The amount of solar energy
The availability of water
The humidity of the air
The temperature of the air.
What is transpiration?
Water is transported from the roots of a plant to its leaves and then lost through pores on the leaf surface.
Condensation occurs when the temp of the air is at dew point but its volume is constant, this occurs when:
-Warm moist air passes over a cold surface
-On a clear winter’s night heat is radiated put to space and the ground gets colder, cooling the air directly in contact with it.
Condensation occurs when what?
The volume of air increases but no addition of heat. This happens when air rises and expands in the lower pressure of the upper atmosphere.
The two main cryospheric processes:
Accumulation and ablation (melting)
Interception storage.
Precipitation that falls on the vegetation services or human-made cover and is temporarily stored on these surfaces.
Overland flow.
The tendency of water to flow horizontally across land surfaces when rainfall has exceeded the infiltration capacity of the soil and all surface stores are full to overflowing.
Percolation.
The downward movement of water within the rock under the soil surface.
Run-off.
All the water enters a river channel and eventually flows out of the drainage basin.
Saturated.
This applies to any water store that has reached its maximum capacity.
Stemflow.
The portion of precipitation intercepted by the canopy that reaches the ground by flowing down stems, stalks or tree bole.
Cryospheric processes
Those processes that affect the total mass of ice at any scale, from local patches to frozen ground, to global amounts.
Drainage basin
This is an area of land drained by a river and its tributaries. It includes water found on the surface, in the soil and in near-surface geology.
Evapotranspiration
The total output of water from the drainage basin directly back into the atmosphere.
Groundwater flow
The slow movement of water through underlying rocks.
Infiltration
The downward movement of water from the surface into soil.
Storm and rainfall event
An individual storm is defined as a rainfall period separated by dry intervals of at least 24 hours and an individual rainfall event is defined as a rainfall period separated by dry intervals of at least 4 hours.
Throughfall
The portion of the precipitation that reaches the ground directly through gaps in the vegetation canopy and drips from leaves, twigs and stems. This occurs when the canopy-surface rainwater storage exceeds its storage capacity.
Throughflow
The movement of water downslope through the subsoil under the influence of gravity. It is particularly effective when underlying permeable rock prevents further downward movement.
Transpiration
The loss of water from vegetation through pores (stomata) on their surfaces.
Water balance
The balance between inputs and outputs in a drainage basin.
Drainage basin as a system
Consider them cascading systems, they are a series of open systems that link together so that the output of one is the input in the next.
Interception store
Vegetation cover, interception stores occur on the leaves/ branches of vegetation, the density of vegetation plays a part.
Infiltration rate
The rate of the water soaking into soil, controlled by gravity, capillary action and soil porosity.
Capillary action
The process of a liquid flowing into a narrow space.
Soil porosity
The amount of soil or open space between soil particles.
Infiltration reaches a constant value after several hours of rainfall, the factors responsible:
-Filling of small pores on the soil surface with water reduces the ability of capillary forces to move water into the soil.
-As the soil moistens, the clay particles absorb water causing them to expand. This reduces the size of soil pores.
-Raindrop impact breaks large soil clumps into smaller particles. These particles clog surface pores.
Soil storage
The amount of water stored in the soil, the pore spaces can be filled with water or air.
Vegetation storage
Most plants remove water from the soil and store it in the structure of the plant.
Percolation
Water moves vertically down through the soil and unsaturated rock.
Channel flow
The movement of water within a river channel.
Run-off
The excess liquid flows across the surface of the land, this occurs when there is more water than the land can absorb.
Hydrological cycle in the Pacific.
Most of the water from the Pacific ocean recirculates between different parts of the Pacific itself and there is little net transport towards land.
Hydrological cycle in the Atlantic and Indian ocean.
The pattern of water exchange between ocean and land is different in the Atlantic and Indian Oceans. 2/3rds of the total net transport of water towards the continents comes from the Atlantic ocean, the rest from the Indian.
Hydrological cycle in the Americas, Europe and Africa.
Most of the continental water for the Americas, Europe and Africa emanates from the Atlantic and is also returned to the Atlantic by rivers.
Water balance.
Within a drainage basin, the balance between inputs (ppt) and outputs is known as water balance or budget.
Outputs in a drainage basin.
Run-off, evapotranspiration, soil and groundwater storage.
River’s regime.
The changes in a river’s discharge over a year.
Water balance formula.
Precipitation (P)= discharge (Q) + evapotranspiration (E) +/- changes in storage (S)
What factor is evapotranspiration closely related to?
Prevailing temperature. The warmer it it, the higher the evapotranspiration.
Potential evapotranspiration.
The amount of water that couold be evaporated or transpired from an area.
River flow
Studied by measuring the discharge of a river, this is defined as the volume of water passing a measuring point in a given time.
Bankfull
The maximum discharge that a river channel is capable of carrying without flooding.
Base flow
This represents the normal day-to-day discharge of the river and is the consequence of slow moving soil throughflow and groundwater seeping into the river channel.
Lag time
The time between the peak rainfall and peak discharge.
Peak discharge
The point on a flood hydrograph when river discharge is at it’s greatest.
Storm flow
Discharge resulting from storm precipitation involving both overland flow, thorughflow and groundwater flow.
Storm hydrograph
A graph of discharge of a river over the time period when the normal flow of the river is affected by a storm event.
Amazon- Changes in total ppt, extreme rainfall events and seasonality may:
-Lead to an overall reduction in river discharge
-Cause an increase in silt washed into rivers, disrupting river transport routes
-Lead to flash flooding
-Destroy freshwater ecosystems, removing a source of protein and income to local inhabitants.
-Destroy water supply for Amazonian people.
Amazon- Warming water temps may:
-Kill of temp-dependent species
-Change the biodiversity of the river system by introducing new species and killing others
-Reduce water-dissolved oxygen concentrations, which could destroy eggs and larvae, that rely on dissolved oxygen for survival
Amazon- Mitigation as a strategy to reduce the effects of environmental change in Amazon:
-Creation of national parks and forest reserves.
-Forest biofuel production could compete with ethanol production from sugar can by 2030
-Reforestation: Brazil’s industrial timber comes from planted forests which make up 2% of the forest area.
-Enrichment of degraded forests by using native species.
How much annual average rainfall is there in the amazon?
2300mm annually
Why does 50% of rainfall in the amazon never reach the ground?
Intercepted by the forest and re-evaporated into the atmosphere
Why is a lack of moisture effecting elsewhere?
Moisture created in the amazon falls as rain in America and Asia, less moisture in the atmosphere and rainfall declines sometimes leads to drought.
Deforestation in the amazon is generally the result of land clearances for:
-Agriculture (soya or pasture land)
-Logging- timber or pulp, selective or clear felling
-Road building- trans amazonian highway
-Mineral extraction
-Energy development-150 new damns in amazon alone (alter hydrological cycle)
-Settlement and population growth, pop grew by 23% between 2000 and 2010
Impacts of deforestation in rivers-
1.Increased soil erosion
2.Flash floods
3.Increasing risk of wildfires
4.Changes to waterways and transport
5.Disrupt water supplies to Brazilians
