Water Cycle Flashcards
(43 cards)
1
Q
What is the systems approach with regards to water?
A
systems approach studies hydrological phenomena by looking at balance of inputs/outputs, and how water is moved between stores/flows
2
Q
What is an open and closed system in terms of water?
A
- open system is one that transfers inputs and outputs of water to external systems e.g. drainage basin
- closed system is one with fixed amount of water with no external inputs/outputs, amount of water remains constant e.g. the hydrological cycle - earth can be considered closed as fixed amount of water -1385 million km3
3
Q
What is blue and green water?
A
blue water - water stored in rivers, lakes (surface water 0.01% of all water) groundwater (1.1% of all water) in liquid form
green water - water stored in soil/vegetation e.g. cacti (biological water - 0.0001% of all)
4
Q
What is the residence time of groundwater compared to atmospheric moisture?
A
groundwater - 10,000 years
atmospheric moisture - 10 days
5
Q
How much water does the USA use?
A
260 gallons per person per day
6
Q
How many dont have access to safe drinking water?
A
1/5
7
Q
How often does a child die of a water-related disease?
A
every 15 seconds
8
Q
What kind of water isnt renewable?
A
- fossil water not considered renewable e.g. many aquifers under Sahara Desert
9
Q
How much of the worlds water is freshwater?
A
2.5%
10
Q
How much freshwater is locked in ice?
A
2/3
11
Q
What three things must be present for rainfall to be created?
A
- air cooled to saturation point (due to altitude) with humidity of 100%
- condensation nuclei (e.g. dust particles) to facilitate water droplet growth
- temperature below dew point (point where dew can form)
12
Q
In what ways can precipitation vary?
A
- amount of precipitation
- type of precipitation
- seasonality
- intensity of precipitation
- variability
- distribution of precipitation within a basin
13
Q
What are the different types of precipitation?
A
- orographic/relief (cloud rises altitude to reflect over mountain, causing precipitation)
- frontal (warm air rises over cold air when they meet, higher altitude causes precipitation)
- convectional (sun sends heat/light to earth, causing evaporation, cloud formation and precipitation)
14
Q
What are the main types of interception?
A
- interception loss (when water is retained by a plant)
- through fall (water drops from leaves)
- stem flow (water trickles along branches/trunk)
15
Q
How much do coniferous trees intercept compared to deciduous?
A
coniferous - 25-35%
deciduous - 15-25%
16
Q
What does the rate of infiltration depend on?
A
- how long rainfall lasts - infiltration capacity decreases with amount of rainfall
- amount of water already in soil
- soil texture - sandy soils have bigger capacity than clay
- vegetation cover (varies throughout the year)
- soil surface/compaction
- slope - steep slopes encourage overland flow, smaller slopes encourage infiltration
17
Q
What are the factors affecting rate of evaporation?
A
- sunlight hours
- temperature
- humidity
- wind speed
- size/depth of water
- vegetation cover
- surface colour
18
Q
What is transpiration?
A
water lost through plant pores
19
Q
What is evapotranspiration?
A
combined effect of evaporation and transpiration
- potential evapotranspiration is that water loss that would occur is an unlimited amount of water was available for vegetation
20
Q
What are the physical factors affecting river drainage basin flow/fluxes?
A
- evapotranspiration
- percolation and groundwater flow
- overland flow
- infiltration and through flow (impermeable soil encourages surface run off, percolation occurs if bedrock is permeable - if soil is permeable but bedrock is not, through flow will occur - more discharge)
- input of rainfall (more=bigger flux so more river discharge)
- interception (presence of vegetation increases lag time so prevents flooding)
21
Q
What are the human factors that impact river drainage basins?
A
- precipitation (human seeding of rainfall, using silver iodine pellets so act as condensation nuclei, attracting water droplets - more precipitation means greater discharge)
- evaporation/transpiration (deforestation decreases rates, reservoirs/dams increase rates e.g. Aswan Dam, channelisation decreases surface storage so reduces evaporation e.g. Mississippi)
- interception (deforestation means less interception so less evapotranspiration and more surface run off, decreases lag time between peak rainfall and peak discharge, increases flooding risk e.g. Himalayas)
- infiltration and soil water (infiltration 5x greater in forests than grasslands, deforestation decreases infiltration and increases soil compaction - however farming practices e.g. ploughing increases infiltration as soil becomes less compact e.g. in foothills of Himalayas
- groundwater (human extraction led to reduction in groundwater e.g. Aral sea in Middle East shrank by 75% from 1960-90)
- dam construction (increases surface area so increased evaporation, reduces discharge downsteam e.g. Aswan Dam causes evaporation losses of 16 billion m3
- urbanisation (impermeable surfaces cause reduction in infiltration, increase surface run off in artificial drains, reduces lag time so increases flooding and discharge e.g. York floods 2015 river Ouse
22
Q
What is hard engineering in terms of water management?
A
use of artificial structures to increase water supplies e.g. mega dams
23
Q
How many major rivers are impeded by dams?
A
60% of worlds major rivers
24
Q
How many dams were there in 2010?
A
845,000 - incl 5000 mega dams
25
What are the types of hard engineering?
- water transport projects (China's South-North Transfer)
- mega dams (Three Gorges Dam)
- desalinisation plants (70% in Middle East)
26
What is water desalinisation and its advantages/disadvantages?
- 30% of irrigated areas suffer from salinity problems
- 12,500 desalinisation plants in 120 countries, producing 14 billion m3 of freshwater per day (in 2002)
- that accounts for less than 1% of world water consumption
- Middle East important user of desalinated water - using 70% of worldwide capacity
- USA important MEDC user particularly in California
- very expensive, limits its use
27
What were the advantages and disadvantages of the Three Gorges Dam?
advantages:
- hydro-electricity produced - clean and will enable growth of industry
- river level will be consistent and allow for shipping along its length and cruise ships at all times, ship-lift will enable large vessels to reach upper parts of river for first time
- 100 million living downstream will be protected from flooding
disadvantages:
- 1.2 million relocated from 13 cities, loss of sacred temples and quality farmland - people forced out and moved to more expensive housing
- reduced sediment flow downstream arms agriculture as farmers rely on fertile silt, silt and rubbish will instead be trapped and built up behind dam
- changing flow may lead to extinction of river dolphin
28
What were the advantages and disadvantages of the South-North Water Transfer?
- 2/3 of Chinese farmland in north but 80% of water in south
- project has capacity to deliver 25 billion m3 of freshwater per year to north through two routes each covering 1000km
- economic cost - canal construction costs at $80 billion in 2015 with high maintenence costs/water prices
- socially - displacement of 300,000 during construction as water level was raised 13m
- environmentally, project doesnt address underlying causes of water insecurity in north incl inefficient agricultural/industrial use and pollution
29
What are the main players involved in hard engineering water management?
- economic players: World Bank, IMF fund mega projects and ensure legislation is in place for trans-boundary schemes and water companies, can run supply business
- environmental players: conservationists fight schemes or seek to save wetlands incl scientists who try to influence water policy
- political players: IGOs e.g. UN responsible for MDGs, and pressure groups that fight against issues e.g. dam construction
- social players: residents, consumers etc who regard access to water a human right, NGOs e.g. water aid provide schemes for LEDCs
30
What is an example of an external water structure?
- Turkey-Israel
- Israel suffering from worst water crisis from droughts of 1998-2001, only sizeable reservoir is Lake Tiberias which is declining
- Manavgat Water Agreement 2002 - brings possiblity of water trade - could reduce tensions and strengthen friendship, Israel could share with Palestine and Jordan
- $1 billion agreement - however didnt go ahead
31
What is the UN's view on water insecurity?
- states water use has been growing at twice the rate of the population
- 2025: 1.8 billion living in absolute scarcity and 2/3 will be in water stress conditions
32
How much of the world population lives in areas receiving 1/4 of world rainfall
66% lives in areas receiving 1/4 of world rainfall annually
33
What does water security refer to?
the capacity of a population to safeguardg sustainable access to adequate quantities of drinking water for sustaining livelihoods/wellbeing
34
What is water stress defined as?
when country's renewable water resources are between 1000-1700m3 per capita - causing frequent/serious restrictions in water use, growing tensions and competition, harvest failures etc
35
What is water scarcity defined as?
when country's renewable water resources are between 500-1000m3 per capita - causing tension/conflict between users, competition, over-extraction of groundwater
36
What is absolute water scarcity defined as?
when country's renewable water resources are below 500m3 - causing widespread restrictions on water use and rationing
37
What are the physical causes of drought?
- climate
- areas of high pressure
- low latitude
- relief
- poor aquifer recharge
38
What are the human causes of drought?
- over-abstraction
- industry/economic growth - factories need water supply
- population growth
- climate change
- thermal pollution - factories pump warm water back in river and this evaporates
39
What is saltwater intrusion and how does this occur?
aquifer abstraction/groundwater pumping at coast can cause saltwater incursion and salinisation of wells, wetlands etc
- freshwater flow decreases and causes saltwater to be drawn into freshwater zones
- this problem increases from storm surges/rising sea levels
- e.g. Samoa gets 35% of water from aquifers, low-lying island means it is threatened by saltwater intrusion, sea level rise strains available water
40
How many people rely on groundwater?
2.5 billion
41
How much waste water is discharged directly into water bodies?
90% of all waste water in developing countries discharged directly into rivers, lakes or oceans
42
Which human activity uses most water?
agriculture at 70% globally
43
What percentage of the worlds aquifers are over exploited?
20%
