Water Flashcards
what is a closed system?
a system of inputs, outputs, stores and flows, from which no matter enters or leaves , only energy does - in this case solar and gravitational potential
what % of global water is stored in oceans?
97%
what % of global water is stored in groundwater?
0.37%
what % of global water is stored in ice caps/glaciers?
2.41%
what % of global water is stored in rivers/lakes?
0.2%
what % of global water is stored in the atmosphere?
0.0001%
why is water important for ecosystems?
soil moisture is needed for plant growth, and rivers and lakes provide drinking water for animals
why is water important for humans?
groundwater, rivers and lakes provide drinking water and can make electricity, important for irrigation, industry and agriculture
what is the global water budget?
the annual balance of water fluxes and the size of water stores. oceans are the largest store, with a residence time of 3600 years
what is a drainage basin?
an open system of inputs, stores, transfers and outputs
what is the input in a drainage basin?
precipitation
what are the stores in a drainage basin?
surface water, interception storage, soil water, channel storage
what are the transfers in a drainage basin?
infiltration, percolation, throughflow, groundwater flow, channel flow, stem flow, overland flow
what are the outputs in a drainage basin?
river runoff, evaporation, transpiration
what factors influence river runoff?
basin size shape and relief, drainage density, soil type, type of precipitation, land use, rock type, temperature
what is convectional rainfall?
as the sun heats the lad and air above, warm air rises, cools and condenses, forming clouds, which rain. this is typical in UK summer
what is frontal rainfall?
warm moist air encounters colder more dense air at regions we call fronts, it is forced to rise above the colder denser air. As the warm air rises it cools, water droplets within it condense and clouds form.
what is orographic/relief rainfall?
moist air is forced to rise over a physical barrier such as a mountain range, as it rises, the warm air cools with height, water vapour condenses to form clouds and eventually it rains over Britain’s highland areas.
As the air descends to the East coast of Britain it warms slightly and there is less rainfall. This results in a rain shadow on Britain’s east coast
define river runoff
when water flows into the sea
define soil water
This occurs when the water infiltrates downwards into the soil.
define stem flow
This is when water flows down vegetation, e.g. a tree trunk.
define surface water
If the ground is hard then the rain lies on the surface in puddles until it soaks into the ground.
define transpiration
A process where water is lost from a plant through the stomata in its leaves into the atmosphere.
define throughflow
This occurs where water flows sideways through the soil.
channel storage
This occurs when the water enters the river and stays there until it reaches the sea.
define channel flow
This occurs when water from the adjacent land flows into a river.
define evaporation
A process where water is lost from the land and river into the atmosphere.
define groundwater flow
This occurs in the zone of saturated rock and is a lateral movement.
define infiltration
where water passes into the soil
define interception storage
This occurs when the rain falls on the trees or grass and is stored until it evaporates or flows downwards.
define overland flow
Where water flows on the ground into the river.
define percolation
The constant movement down through the soil and rock.
what human activities affect the hydrological cycle?
deforestation, irrigation, urbanisation, conversion of forest to farmland, dam building, over abstraction of water, afforestation, flood control
what is the water balance?
the balance between inputs and outputs, shown using the formula
precipitation = streamflow + evapotranspiration +/- change in storage
what is discharge?
volume of water flowing in a river channel at any given point, measured in cubic metres per second (CUMECS)
what does a river regime show?
annual variation in discharge of a river
what is an even river regime
where discharge doesn’t change, is constant, steady
what is a simple river regime
where river experiences seasonally high discharge followed by low discharge
what is a complex river regime
river crosses different climate zones over different reliefs so experiences different seasonal and climatic events, also affected by human factors
what physical factors affect river regimes?
precipitation, climate, season, geology, soil, vegetation, river length
what human factors affect river regimes?
dams, where monitoring station is placed, global warming, water abstraction
what do storm hydrographs show
Show how storm event affects drainage basin
give examples of sustainable drainage systems (SuDS)
green roofs, permeable pavements, rainwater harvesting, wetlands
causes of drought
ENSO cycles, blocking anticyclones, movement of ITCZ
explain el nino
weak trade winds mean warm water moves towards south america so there will be increased rainfall and floods, while there will be dry conditions and drought in australia due to sinking air and lack of warm water
explain la nina
strong trade winds move warm water westward to australia , where increased heat causes air to rise rapidly forming thick clouds, heavy rain and floods, while there is a strong upwelling of cold water in south america where high air pressure causes drought
how does human activity increase drought risk?
abstraction depleting groundwater stores, deforestation causing less infiltration into groundwater, urbanisation, dam building reducing river flow downstream, agriculture using large amounts of water
how does drought impact wetland ecosystems?
vegetation deteriorates, food chain is affected, less percolation means lower water table, may dry out and be susceptible to wildfires
what are the physical causes of floods?
Intense storms
Heavy and prolonged rainfall
Extreme monsoonal rainfall
Snowmelt
Low pressure systems
ENSO
Storm surge
Rock/soil type
what are the human causes of floods?
Urbanisation
Changes in land use
Deforestation
Soil compaction
Mismanagement of rivers
Hard engineering
Poverty
how does climate change affect evapotranspiration?
In large areas of Asia and North America actual evaporation is increasing, although increased cloud cover from water vapour may limit this. Transpiration is linked to any vegetation changes, which are linked to changes in soil moisture and precipitation.
how does climate change affect groundwater flow?
No definitive link between climate change and groundwater amounts. Human abstraction is the dominant impact on supplies, especially for agriculture.
how does climate change affect the cryosphere?
glaciers have retreated globally, and glacial thinning has accelerated due to rapid temperature increase and changes in precipitation (more rain less snow)
how does climate change affect precipitation input?
Widespread increases in intense rainfall events have occurred although overall amounts have remained steady or even decreased. Areas of precipitation increase include the tropics ad high latitudes. Additionally length, frequency and intensity of heat waves has increased widely especially in southern Europe and southern Africa. More precipitation now falls as rain, not snow.
how does climate change affect soil moisture?
likely to increase as precipitation increases
how does climate change affect oceans?
in areas of ocean warming increased evaporation occurs
how does climate change affect reservoir, lake and wetland storage?
Regional variations in Lakes and reservoirs have been linked to regional variation in climate e.g. Lake Chad. There are changes in wetland storage however there is not enough evidence to suggest this is a result of climate change.
how does climate change affect permafrost?
Changes in the physical climate at high latitudes, primarily increasing air and ocean temperatures, are leading to permafrost degradation in northern areas. This has an impact on groundwater supplies.
how does climate change affect runoff and stream flow?
With more climate extremes will come an increase in hydrologic extremes, with more low flows (droughts) and high flows (floods). An accelerated cycle with more intense rainfall will result in higher run-off rates and reduce infiltration.
how does climate change affect snow?
The length of the snow cover season has decreased, especially in the northern hemisphere in the last 50-100 years. Snowmelt is earlier.
factors affecting water supply
climate, river systems, geology
factors affecting water demand
urban population, agriculture, leisure industry, power supply
factors causing water stress
agriculture, climate change, population, low rainfall, pollution, industrialisation, urbanisation, poor management/distribution
what is water stress
when demand exceeds supply or poor water quality restricts use; below 1700m^3 per person annually
what is water scarcity
below 1000m^3 per person annually
what is water insecurity
where present and future supplies cannot be guaranteed
physical causes of water insecurity
climate variability, salt water encroachment
human causes of water insecurity
over abstraction, industrialisation, pollution, rising demand, population growth, agriculture
how does water affect the poverty cycle?
poor water > illness > poor education > low or no income > poor household
