water Flashcards
how much of water budget is oceans
97%
how much of water budget is fresh water
2.5% of which 69% is glaciers and ice, and 30% is groundwater
size of water store in atmosphere
0.001%
size of water store in groundwater
1.1%
size of water store in biosphere
0.0001%
size of water store in cyrosphere
1.9%
fluxes
measure the rate of flow between stores
stores
reservoirs where water is stored
closed system
fixed amount of water in earth and atmosphere no external imputs or outputs
open system
receives inputs and transfers outputs of energy to other systems
residence time
average time a water molecule will spend in a store
drainage basin
area of land drained by a river and its tributaries
watershed
boundaries of drainage basin - open system
what is needed for precipitation
air cooled to relative humidity of 100%, condensation nuclei to facilitate Goth of water droplets, and temperature below dew point
factors which influence percipitation on drainage basin (4)
amount of precipitation, type of precipitation, seasonality (rainfall patterns in different climates), intensity of precipitation
fluxes on drainage basin
interception and infiltration
what effects infiltration rates (5)
duration of rainfall, saturation of soil, soil type, vegetation, slope angle
overland flow
also know as surface runoff, main way water returns to river
through flow
lateral transfer of water down slopes through soil
percolation
transfer of water through rocks vertically
groundwater flow
transfer of water through rocks sideways
outputs of drainage basin - evaporation and factors effecting
moisture is lost directly into atmosphere from water surfaces and soil - climate, hours of sunshine, windspeed
outputs of drainage basin - transpiration and factors effecting
water is lost from plants through pores into atmosphere - time of year, type of vegetation
outputs of drainage basin - evapotranspiration
combined effect of evaporation and transpiration
physical factors that effect drainage basin - climate
influences type and amount of precipitation, type of vegetation and evaporation
physical factors that effect drainage basin - soils
amount of infiltration and trough floe indirectly type of vegetation
physical factors that effect drainage basin - geology
impact subsurface processes such as percolation and groundwater flow
physical factors that effect drainage basin - relief
altitude can impact precipitation totals and slop cam affect amount of runoff
physical factors that effect drainage basin - vegetation
ands of interception, infiltration, and transpiration rates
human factors effecting drainage basin - deforestation
dense vegetation means that interception and evapotranspiration rates are high so high humidity and high rainfall (self sustaining cycle), removing this effects cycle resulting in increased runoff and river discharge
example of deforestation effecting drainage basin
between 1960 and 1997 the Tocantins river showed 25% increase in discharge coinciding with increased rates of deforestation
human factors effecting drainage basin - changing land use
increase of urbanisation means more impermable surfaces reducing infiltration and increase surface runoff (drains, lag times) increasing river discharge
example of changing land use effecting drainage basin
urbanisation has increased flood risks in many uk towns, in Upton upon severn flooding occurred 6 times in 2007
human factors effecting drainage basin - over abstraction
as population increases higher demand for water, in some places groundwater is being abstracted quicker than being replenished lowering groundwater table
example of over extracting effecting drainage basin
over 40% of Londons water comes from chalk aquifers rest abstracted from Thames basin which is home to 13 million, risks of drying up
water budget
shows annual balance between inputs and outputs
river regime
annual variation in discharge or flow of a river at a particular point
what influences river regime (6)
size of river, amount pattern and intensity of rainfall, tenpetures, geology and soils, type of vegetation cover, human actives
meteorological drought
shortfalls in precipitation as a result of low precipitation, high tempetkres, high winds. which increases dry period
ENSO cycles
El Niño southern oscillations is a naturally occurring phenomena that involves the movement of water in the equatorial pacific
hydrological droughts
reduced stream flow and ground water levels, which decreases due to low precipitation inputs and high evaporation. also causes reduced storage in lakes and resivours, as low recharge speed
agricultural drought
rain defiencency less to a deficiency of soil moisture and soil moisture availability which has a knock on effect on plant growth and reducing biomass
social - economic drought
all 3 types of drought can led to social- economic / famine drought with widespread failure of crops food shortages leading to malnutrition, rural economy can collapse requiring aid
human contribution to droughts
over extraction of water as ground water aquifers take long time to replenish so if lots of water taken can led to desertification
key features of wetlands (3)
act as temporary water stores, wetlands act as filters by trapping and recycling nutrient and pollution to maintain water quality. they are high in biodiversity
impact of droughts on wetlands
vegetation will deteriorate, volume of water stores will decrease, water tables will drop, habitats damaged
impact of droughts on forests
trees take 1 - 4 years to recover, pines have less resilience to droughts, drought sled to foliage loss, impared growth, accusation of pests and disease
metrological causes of flooding
prolonged heavy rain like in uk when low pressure systems, ice and snow melting. in Asia monsoon season can led to flooding
human actions which can exacerbate flooding (7)
changing land use, dams, urbanisation, deforestation, grazing animals, ploughing compact soils
social-economic impacts of flooding
death of crops, famine, loss of communication of transport, loss of infrastructure.
enviromental impacts of flooding
maintaining ecosystem functions, moving sediment, eutrophication, loss of soil wildlife
how does climate change effect inputs of hydrological cycle
effects precipitation by increasing intense rainfall events, increased snow melt, at same time length, frequencency and intensity of heat waves have also increased
how does climate change led to increased flood risk
increased air temps (global warming) increasing convection and evaporation, increased condensation and cloud cover, increased precipitation in low pressure areas so increase flood risk
why is it difficult to predict climate change (3)
global records incomplete, oscillations of ENSO and climate warming difficult to distinguish, climate dynamics only partially understood
how has climate change effected snow and permafrost
active layre melting impacting ground water supplies, and releases gases
how does climate change increase run off and stream flow
with climate extremes evidence to suggest that will be increase in hydrological extremes and more intense rainfall will increase run off and reduce infiltration
climate change on stores of reservoirs lakes and wetland storage
regional variation in lakes and reservoirs have been linked to regional changes in climate, changes in wetland storage are occurring but cannot be exclusively linked to climate change.
water stress
if renewable water sources are between 1000- 1700m3 per capitita - led to serious restrictions on water
water scarcity
if renewable water resources are between 500 - 1000m3 per demand - less to unsatisfied demand, tention and conflict
absolute water scarcity
renewable resources are less than 500m3 per capita - this led to widespread restrictions and water rationing
how much of population lives in area recieving how much rainfall
66% of world population live in areas one recieving 25% of worlds annual rainfall
threats on water insecurity - climate change
creating drought conditions as tempetkres increase
threats on water insecurity - population growth
increased demand for water so over extraction occurs
threats on water insecurity - agriculture
they need to irrigate land so extracting it from water sources
threats on water insecurity - competition between countries
as demand increases country’s and competing with each other for increased allocation placing pressure between nations
salt water encroachment
the movement of saltwater into fresewater aquifers due to sea levels rise, storm surge and human abstraction of groundwater which lowers water table
what have unified nations world water devolpment said will happen
increase of water demand of 55% by 2050, and a 40% global water deficient by 2030
what 3 factors is water scarcity related to
availability, access, usage
physical scarcity
determined by climate and balance of inputs and outputs, factors scubas topography are regional factors which can impact. can also be local factors such as geology
economic scarcity
has very different global distribution, associated with developing countries that lack capital and technology and good governance
prices of water effecting water scarcity
determined by;
physical cost of obtaining supply, demand and infrastructure.
importance of water supply for industry
over 20% of all freshwater is used in energy production and industry. concern is that industry production shifting towards emerging nations such as china who contaiminate groundwaters and river
water supply and human wellbeing
some populations still rely on unimproved water (15% of population) and no sanitation (2.5 million no asess) . which can led to deisease especially when combined with poor hygiene
how many transboundary water basins lack management
158 / 263
how many people rely on groundwater
2 billion
the potential for water conflict
conflict in inequalities over water allocation, natural environment and vulnerable people are often biggest losers
advantages of desalination
creates drinking water, jobs, salt
disadvantages of desalination
can create pollution (hot water put back into ocean) expensive
advantages of dams
prevent flooding, large water storage, produces hep
disadvantages of dams
harms ecosystems, sediment, can decrease discharge downstream, expensive, creates pollution during building
advantages of water division projects
can prevent water inequality, jobs, distributes waters
disadvantages of water division projects
expensive, impacts habitats
