water Flashcards
stores/stocks
reservoirs where water is stored e.g the oceans
fluxes
measure the rate of flow between stores
processes
physical mechanisms which drive the fluxes of water between the stores.
cryosphere
areas of earth where water is frozen into snow/ice. During the last ice age sea levels were 140m lower than they are today.
systems approach
systems approaches study hydrological phenomena by looking at the balance of inputs and outputs, and how water is moved between stores and flows.
open system
receives inputs from and transfers outputs of energy to other systems. For example a drainage basin.
closed systems
Fixed amount of water in the earth and atmosphere system (1385 milion km³). There are no external inputs or outputs- the amount of water is constant. For example the hydrological cycle.
blue water
water is stored in rivers, streams, lakes and groundwater in liquid form
green water
Water stored in the soil and vegetation.
residence time of oceans
3,600 years
residence time of ice caps and glaciers
15,000 years
residence time of groundwater
up to 10,000 years
residence time of rivers and lakes
2 weeks to 10 years
residence time of soil moisture
2-50 weeks
residence time of atmospheric moisture
10 days
residence time of biological water (biosphere)
1 week
what type of system is the hydrological cycle
a closed system
what type of cycle is the drainage basin
an open system
what is the global water budget
the annual balance of water fluxes (flows) and the size of the water stores.
is water a renewable or non renewable resource
Water stores have different residence times (amount of time the water is held for) but it is generally considered a renewable resource.
There is only one type of water which is the exception- Fossil water. This is water which has been held in an undisturbed space e.g aquifers for millennia. If this was to be used, there is little or no recharge of this store so it is considered a non-renewable resource. There are many aquifers and fossil water stores beneath the Sahara desert
what % of total global water is from oceans
96.5%
what % of freshwater is from groundwater
30.1%
what % of freshwater is from glaciers and ice caps
68.7%
what % of surface water and other freshwater is from ground ice and permafrost
69%
what % of surface water and other freshwater is from lakes
20.9%
how does the water budget limit water available for human consumption
fossil water
cryosphere losses
fossil water
untapped ancient stores of freshwater that exists in the polar regions and beneath deserts in the form of aquifers.
Once it’s used, there is little to no significant recharge, effectively making it non-renewable.
eg of fossil water
E.g. Kenya’s Lotikipi aquifer contains an estimated 200 billion cubic metres of freshwater.
cryosphere losses
Major ice sheets store water for very long periods (such as Antarctica and Greenland).
Ice core dating has suggested that the residence time of some water in the Antarctic ice is over 800,000 years.
69% is locked up in snowflakes, ice sheets/caps and glaciers found in high latitudes and high-altitude locations – this water supply is largely inaccessible to humans.
what are the two processes that drive the hydrological cycle
solar energy
gravitational potential energy
solar energy
This is when energy from the sun heats water and causes evaporation/transpiration.
More evaporation occurs as the global climate warms, which increase moisture levels in the atmosphere.
This in turn can lead to increased condensation as air cools, and therefore greater precipitation.
gravitational potential energy
This keeps water accelerating through the system under gravity
On land, energy is converted into kinetic energy as the water moves through the system by plant interception, or over land surface run-off.
where is solar energy concentrated
in the Tropics, where much is absorbed by the sea.
This evaporation produces high rainfall (74% of the world’s rainfall occurs at sea most within the Tropics). The rest is unevenly distributed e.g. the seasonal monsoons and droughts of Asia and Africa contrast with the temperature climates of North West Europe.
what do different climatic regions vary in
the nature and size of their inputs, transfers and flows of water.
how does solar energy affect polar regions and tropical rainforests
there is polar hydrology and tropical rainforest hydrology
how do seasons vary for polar hydrology
there are freeze thaw seasonal differences
how do seasons vary for tropical rainforest hydrology
few seasonal differences
effect of winter in polar hydrology
winter snow insulates the ground and 85% of solar radiation is reflected
effect of dense vegetation in tropical rainforest hydrology
dense vegetation intercepts and consumes up to 75% of precipitation
charachteristics of places with polar hydrology
lakes and rivers are frozen
limited vegetation cover reduces heat absorption
spring thaw causes rapid run off
summer thaw produces surface run off, increasing evaporation tenfold
freeze thaw cycle causes seasonal release of biogenic gases(caused by plant decomposition) into the atmosphere as well as carbon and nutrients into rivers and seas
annual precipitation of polar hydrology
less than 200mm
what type of rain is polar hydrology charachterized by
orographic or frontal precipitation and low humidity
charachteristics of tropical rainforest hydrology
50-75% of precipitation returns by evapotranspiration
evapotranspiration cools the air as energy is used during the process
rainforests generate their own rain, most is recycles within the tropics
less than 25% of rainfall reaches rivers or other surface water
there is limited surface infiltration or groundwater
rainforests are ‘cloud factories’
deforestation reduces evaporation- in turn reducing vapour and local rainfall
constant high temperatures
annual precipitation in tropical rainforest hydrology
over 2000 mm
what type of rainfall is tropical rainforest hydrology charachterised by
convectional rainfall and high humidity
what two types of water are exceptions to water being a renewable resource
fossil water
cryosphere losses
drainage basin system
a subsystem within the global hydrological cycle. It is an open system as it has external inputs and outputs that cause the amount of water within the basin to vary over time.
drainage basin definition
the area of land drained by a river and its tributaries. This area can also be referred to as the rivers catchment area.
precipitation definition
any form of water falling from the sky
watershed definition
the boundary of a drainage basin. This is usually a ridge of high land which divides and separated the water flowing into different rivers.
interception loss definition
this occurs when water is intercepted by vegetation and retained by the plant- the water will never reach the ground.
factors which effect basin flows/fluxes
forestry
relief/topography
flooding
input of rainfall
farming
vegetation
interception
infiltration and through flow
urbanisation
geology and soils
overland flow
percolation and groundwater flow
climate
evaporation and transpiration
what 3 things must be present for rainfall to be created
Air that is cooled to saturation point with a humidity of 100%
Condensation nuclei, such as dust particles to facilitate the growth of water droplets in clouds
A temperature below dew point (the temperature at which dew forms
what are the 3 types of rainfall
convectional
cyclonic/frontal
orographic
what are the 3 main types of interception
interception loss
through fall
stem flow
interception loss
water retained by a plant
through fall
when water drops from the leaves
stem flow
when water trickles along branches, twigs and the stem/trunk
what is infiltration
the process by which water soaks into the soil
what is infiltration capacity
The infiltration capacity is the maximum rate at which rain can be absorbed by soil
what does the rate of infiltration depend on
The infiltration capacity will decrease in time throughout a period of rainfall
The rate of infiltration depends on the amount of water already in the soil
Soil texture- sandy soils have a greater capacity than clay soils
Vegetation cover which varies throughout the year
Soil surface- compacted soils will have a reduced capacity
Slope/ topography- steep slopes encourage overland flow, smaller gradients encourage infiltration
what s through flow
the lateral transfer of water down slope through percolines (lines of water flow between layers of soil)
what is percolation
Percolation is the vertical movement, groundwater flow the lateral movement.
evaporation
Physical process by which moisture is lost into the atmosphere. It is a direct result of insolation (heat and light energy from the sun)
what factors determine rate of evaporation
Hours of sunlight
Temperature
Humidity
Wind speed
Size and depth of water
Vegetation cover
Surface colour
what is transpiration
Water lost through plants through their pores (stomata).
evapotranspiration (EVT)
Combined effect of evaporation and transpiration
potential evapotranspiration (PEVT)
The water loss which would occur if there was an unlimited amount of water in the soil for use by vegetation
what physical factors influence the drainage basin
rainfall
interception
infiltration and through flow
overland flow
percolation and groundwater flow
evaporation and transpiration
what are the main physical features that affect the drainage basin
climate
soils
geology
relief
vegetation
impacts of human actvivity on precipitation- affecting water basins
Human seeding of rainfall. Silver iodine pellets or ammonium nitrate are sent up into the sky to act as condensation nuclei to attract water droplets which will lead to increased rainfall in drought stricken areas. It has variable results.
how does cloud seeding work
1- silver iodide is released by a plane or ground based genorator
2- silver iodide particles reach the targeted cloud
3- the silver iodide aids in the formationof ice chrystals
4- ice chrystals become large enough to fall and create snow
eg of cloud seeding
ABU DHABI // Daily cloud seeding by the National Centre of Meteorology and Seismology may have increased the amount of rain across the country. The national weather bureau said it had launched about 20 rain-boosting flights since Thursday to blast hygroscopic salt, which attracts and holds water, into the clouds to try to produce more moisture.
what did studies conducted between 2002 and 2006 in abu dahbi suggest
rain enhancement programme could increase rain between 10 and 30%
effect of deforestation on evaporation and evapotranspiration
Deforestation would decrease the rate of evaporation and evapotranspiration, for example in the Amazon Rainforest, Brazil
effect of damn construction on evaporation and evapotranspiration
Reservoirs and dams, for example the Aswan Dam in Egypt will increase evaporation and evapotranspiration
effect of channelisation on evaporation and evapotranspiration
Channelization of rivers cuts down surface storage and so would reduce evaporation
effect of deforestation on interception
less evapotranspiration would lead to more surface run off. This would increase the chances of flooding and decrease lag time between peak rainfall and peak discharge in a river (volume of water in a river). This is a large issue in the Himalayas, Nepal
effect of afforestation on interception
should increase evapotranspiration and lengthen lag time which would prevent flooding. This has been seen in Plynlimon, Wales which is the source of the River Severn
how many times greater is infiltration under forests than grasslands
5 times
effect of farming/deforestationon infiltration
When deforestation occurs for farming there is les interception, more soil compaction and so less infiltration. However, some farming practices such as ploughing, increases infiltration rates as soil is made less compacts. E.g. in the foothills of the Himalayas , Nepal
effect of human activity on groundwater supplies
Human use of groundwater for irrigation or industry has lead to huge reductions in groundwater. For example the Aral sea which is between Kazakhstan and Uzbekistan began to shrink in 1960 as a result of over abstraction for the cotton industry. By 1994 the volume of water had reduced by 75%
what are many british cities doing in terms of groundwater
Conversely, in many British cities are reducing abstraction of groundwater used in industry and are now finding levels are starting to rise and causes issues for underground transport such as in London as well as many households finding their cellars are flooding more regularly.
effect of damn construction on water basins
Dams increase surface water stores and increase evaporation rates. They also reduce the discharge of the river downstream. Lake Nasser behind the Aswan Dam in Egypt is estimated to have evaporation losses of up to 16 billion cubic metres every year- that is 30 % of the water volume from the river Nile
effect of urbanisation on drainage basins
Impermeable surfaces reduce infiltration and increase surface run off and through flow through artificial drains. Reduced lag time and increases the risk of flooding and the discharge of rivers and streams. Flooding has become more apparent in many cities across the UK e.g York floods of 2015.
what does the water budget show
the annual balance between inputs and outputs
what does the water budget help to identify
The water budget helps to identify periods of time where there is a positive water budget (when precipitation would exceed evapotranspiration) and we would have a water surplus. OR identify a negative balance when evapotranspiration would be larger than precipitation and we would experience water scarcity and have an increased drought risk.
water balance equation
Precipitation (P)= channel discharge (Q) + evapotranspiration (E) +/- change in storage (S)
whats a soil moisture budget
It reflects the annual changes in precipitation and evapotranspiration and allows assessment of the soil moisture availability.
soil moisture deficiency
Soil water store has been used up. Plants will only survive if they have adaptations to survive periods of drought or they are irrigated.
soil moisture surplus
Precipitation greater than evapotranspiration. Run off recharges groundwater supply- the soil is at field capacity.
what will happen at the maximum annual temperature
River levels will fall, crops will need irrigation.
soil moisture utilisation
Evapotranspiration is exceeds precipitation. Water is being drawn up through the soil by capillary action- the water is being used up.
field capacity
. When the soil store is at full capacity and cannot hold anymore.
soil moisture recharge
When evapotranspiration decreases so that it is lower than precipitation and the soil store will start to recharge.
what are river regimes
River regimes are the annual variation in discharge of a river at a particular point and is measured in cumecs.
what factors impact river regimes
size of the basin
amount, pattern and intensity of precipitation
temperatures
geology
vegetation cover
human activities
what does a storm hydrograph show
shows variation in a rivers discharge at a specific point over a short period of time (normally before, during and after a storm). The shape of the graph can be impacted by a range of human and physical factors. The hydrograph will either be described as flashy or subdued. A flashy hydrograph will have a rapid increase in discharge and a high chance of flash flooding.
discharge
The volume of water in a river in a given point
rising limb
The increase in discharge in response to surface runoff and through flow from a rainfall event until peak flow is reached.
falling limb
The decline in discharge that occurs after peak flow. This is usually less steep than the rising limb because through flow is being released slowly into the channel
lag time
The difference in hours and minutes between the time of maximum precipitation and peak discharge. Lag time will vary heavily based on human and physical factors. Rivers with a short lag time have higher peak discharges and are more prone to flooding.
base flow
The contribution to river flow from long term storage sources such as permeable rocks, areas of bog and marsh and moorlands.
appraoch segment
The discharge of the river before the storm (antecedent flow rate)
peak discharge
The maximum discharge by a stream or river in response to a rainfall event
bankfull discharge
Occurs when the water level in a river reaches the top of its channel. Any further increase would result in flooding of the surrounding land.
how do different human and physical factors affect storm hydrographs
Different human and physical factors would lead to different shapes of od storm hydrographs being created
flashy hydrograph
short lag time and high peak discharge
subdued hydrograph
long lag time and low peak discharge
what drainage basin size would create a flashy hydrograph
small basins
water will reach the channel rapidly as it has a shorter distance to travel
what drainage basin size is likely to produce a subdued hydrograph
large basins
water will take longer to reach the channel as it has a greater distance to travel
drainage basin shape creating a flashy hydrograph
circular basins
it will take less time for the water to reach the channel as all the extremeties are equidistant from the channel
drainage basin shape creating a subdued hydrograph
elongated basins
water will take a long time to reach the channel from the extremities of the drainage basin
drainage basin relief creating a flashy hyddrograph
steep slopes
water flows rapidly downhill and reaches the channel quickly
drainage basin relief creating a subdued hydrograph
gentle slopes
water can infiltrate into the ground and travel slowly to the channel through the soil and rock
soil type creating a flashy hydrograph
clay soils and thin soils
clay soils have a low porosity and the grains swell when they absorb water, so water infiltrates slowly
thin soil becomes saturated quickly
soil type creating a subdued hydrograph
sandy soils and thick soils
sandy soils have high porosity so the water can infiltrate
deep soils allow more infiltration
rock type creating a flashy hydrograph
impermeable rocks
water cant percolate into the rock
increasing surface ryn off to rivers
rock type in creating a subdued hydrograph
permeable rocks
water percolates through pore spaces and fissures into thr groundwater store
drainage density in creating a flashy hydrograph
high drainage density
a large number of surface streams per km2 means the storm water will reach the main channel rapidly
draianage density in creating a subdued hydorgraph
low draianage density
a small number of surface streams per km2 means the water travels slowly through the soil and rocks to the river
natural vegetation creating a flashy hydrograph
thin grass intercepts little water and there is little loss by evapotranspiration, so more water reaches the channel rapidly
effect of draiange density in creating a subdued hydrograph
low draianage density
a small number of surface streams per km2 means the water travels slowly through the soil and rocks to the river
natural vegetation creating a flashy hydrograph
thin grass intercepts little water and there is little loss by evapotranspiration
so more water reaches the channel rapidly
effect of drainage density on a subdued hydrograph
forest and woodland
intercepts water and has high rates of evapotranspiration
less water reaches the channel and more slowly
land use creating a flashy hydrograph
urban- urban surfaces have more hard surfaces such as roads and drains that carry the water rapidly and directly to the river
land use creating a subdued hydrograph
rural- vegetated surfaces intercept water and allow infiltration so water travels slowly to the river channel
precipitation duration creating a flashy hydrograph
prolongued
the water table rises and the soil becomes saturated causing surface run off which travels rapidly to the river channel
precipitation duration creating a subdued hydrograph
short duration
most of the water infiltrates into the soil and travels slowly through the soil into the rocks before reaching the channel
snowfall creating a flashy hydrograph
fast snowmelt
meltwater cant infiltrate into the frozen ground so it flows rapidly over the surface into the river channel
snowfall creating a subdued hydrograph
slow snowmelt
the ground thaws with the snow so the meltwater can infiltrate into the soil and rocks before reaching the channel
evapotranspiration creating a flashy hydrograph
low rates
fewer losses from the draianage basin system will increase discharge into the river channel
evapotranspiration creating a subdued hydrograph
high rates
high evapotranspiration losses will reduce discharge into the river channel
what is drought
a very complex geographical phenomenon although the fundamental definition is a ‘shortfall’ or deficiency of water over an extended period of time.
how does the National Drought Mitigation Centre in the USA describe drought
as an ‘insidious hazards of nature’ implying it develops gradually with harmful impacts.
how does the UN define drought
‘an extended period of deficient rainfall relative to the statistical multi year average for a region’
what are the 4 types of drought
meteorological
agricultural
hydrological drought
socio economic drought
meteorological drought
Occurs when long-term precipitation is much lower than normal, but there is no consensus regarding the threshold of the deficit or the minimum duration of the lack of rainfall that turns a dry spell into an official drought.
agricultural drought
Occurs when there is insufficient soil moisture to meet the needs of a particular crop at a particular time. It is caused by a number of factors such as precipitation shortages, difference between actual and potential evapotranspiration, soil water deficits and reduced groundwater levels.
hydrological drought
Occurs when there are deficiencies in surface and subsurface water supplies as measured in rivers, reservoirs lakes and groundwater. It originates with a deficiency in precipitation but it is usually out of phase with or after the occurrence of meteorological and agricultural droughts.
socio economic drought
Occurs when the water demand for social and economic purposes exceeds water availability. This could be the result of a weather-related shortfall in water supply or the overuse of the available water supplies. It is different from the other types of drought as it is dependant upon spatial variations in supply and demand
what can all the 4 types of drought lead to
famine drought
famine drought
As crops fail, food production becomes limited and so food shortages and famine occur. Such humanitarian crisis occur frequently in the Horn of Africa. International solutions are often needed to support these areas.
what does Teleconnection in atmospheric science refer to
anomalies which relate to each other over large distances.
what are the main physical causes of drought
ITCZ
Mid latitude blocking anticyclones
Mid latitude blocking anticyclones
El Nino Southern Oscilation (ENSO
General processes taking place
step 1 of the global atmoshperic circulation system
intense solar radiation at the equator warms the air which rises aand starts convection
the air cools as it rises and water vapour condenses to form clouds and rain
the second step of the global atmoshperic circulation system
the subtropical high-pressure zone is created where air that had risen at the equator has cooled and so sinks to form a belt of high air pressure and hot, dry conditions
third step of the global atmoshperic circulation system
the air returns to ground level at the equator creating trade winds
4th step of the global atmospheric circulation system
the trade winds meet at the Intertropical convergence zone (ITCZ) where the warmed air rises
the position of the ITCZ moves with the seasons in the northern hemisphere
summer (june-august) the ITCZ is north of the equator
in december-febraury the southern hemishere is tilted towards the sun and therefore the ITCZ is south of the equator
this movement causes alternating wet and dry seasons in the tropics
step 5 of the global atmoshperic circulation system
the warm air moving from the subtropics to mid-latitudes meets cold polar air at the polar front where the warm less dense air rises causing condensation and rainfall
step 6 of the global atmospheric circulation system
the warmer air rises into the polar front jet stream and is transferred at high altitude towards the poles where it cools and sinks
this creates a movement of air at ground level back towards the equator
what is the ITCZ
belt of low atmospheric pressure located around the equator
it moves north or south of the equator seasonally eg further north during the northern hemispheric summer
what happens at the ITCZ
air rises as a result of intense heating by the suns energy
there is also high evaporation from oceans
this means it causes the wet and dry seasons in some world regions
mid latitude blocking anticyclones
in mid latitudes frontal precipitation is created in low pressure systems that form along the polar front where warm tropical air rises over cold polar air
depressions move from west to east in the mid latitudes as a result of the coriolis force (caused by the rotation of the earth)
what are depressions in the mid latitudes tracks directed by
the polar front jet stream
which is a fast moving meandering belt of air in the upper troposphere
what happens when the loops pf the jet stream stabilise or break
allows high pressure areas (anticyclones) from the subtropics to move northwards
what do the anticylones bring
stable weather conditions
with little precipitation (heat waves) while rain bearing depressions are forced around them, usually to the north and occasionally south
causing drought in mid latitude countries such as the uk
what does the stability of antocyclones mean
stability- sinking air and calm conditions
they can persist and block weather systems from the west for up to 2 weeks
if this is repeated for over a few months, normal precpiptation levels are greatly reduced which may cause drought
eg of anticyclones creating drought
Met office reported from 2010 to 2012 much of central eastern and southern england and wales experienced a prolongued period of below average rainfall due to blocking anticyclones
what is an el nino southern oscilation cycle
a naturally occuring large mass of very warm seawater in the equatorial pacific ocean
the warm water is usually located in the western pacific where its pushed by ocean currents, trade winds and the walker circulation cell in the atmospherew
what happens every 7 years in the el nino cycles
pushing forces weaken allows mass of warm water to move eastwards towards the west coast of central and south america
wheerever this mass of warm water is located, evaporation and precipitation rates are higher
whereas areas of cooler water such as the cold current (humbolt current) that flows along the peru-chile coastline bring drier weather
what does an el nino event do
reduces precipitation in the western pacific and the affected countries experience drought
eg 1997 to 2009 millenium drought in australia
what are the two phases of enso cycles
el nino
la nina
when does la nina occur
when the warm mass of water is pushed even further west than normal which causes drought in peru and california
where does enso originate and what does it cause
global variations in rainfall patterns by changing the global atmospheric circulation creating both droughts and floods in different areas of the world
eg of a strong la nina
severe east african drought of 2011
human actvities which can contribute to drought
over abstraction
buldling reservoirs
deforestation
overgrazing
enhanced greenhouse effect
urbanisation
what is an ecosystem
is an interconnected community of living organisms within a defined physical environment.
what is ecosystem functioning
Ecosystem functioning refers to the biological, chemical and physical processes that take place within an ecosystem
what are the two types of amenities ecosystems provide for us
tangible amenities (ones u can touch)
intangiable amenities (cant touch)
why are ecosystems vulnerable to drought
All ecosystems components are dependant upon water supplies so all ecosystems are vulnerable to drought. Levels of ecosystem resilience to drought vary with desert and semi arid areas ecosystems being the most resilient.
what key functions do wetland environments perform
They act as temporary water stores so protect areas from flooding, recharge aquifers and protect land from erosion
Chemically, wetlands act like giant water filters by trapping and recycling nutrients as well as pollutants which helps to maintain water quality.
They have a very high biological productivity and support very large food web. They provide nursery areas for fish and refuge to migrating birds.
For humans they therefore are of huge benefit as both a resource and service.
what is a wetland
an area of land saturated with water, either permanently or seasonally. They can include: marshes, swamps, fens and bogs.
what can drought impact in wetlands
Volume of water store
Habitats
Soil moisture
Soil quality
Risks of flooding
Concentration of nutrients in the water
Food webs
Extinction
how are the everglades florida north america affected by drought
Less interception and vegetation will deteriorate.
Less infiltration and percolation so water table levels will fall
Evaporation rates will increase reducing the volume of water
Increase in wildfires as a result of increased desiccation (extreme dryness).
how are wetlands fed
ground water stores
by rivers
how long do trees take to recover their normal growth rates after a period of drought
1-4 years
what species of tree has a lesser resilience to drought
pines
what have droughts led to in forests
Drought led to foliage loss, impaired growth, accumulation of pests and diseases, long lasting damage to vascular tissues impairing water transport within trees.
how do forests act as carbon sinks
The Global Footprint Network (GFN) calculate that forests store on average 0.73 tonnes of carbon per hectare per year.
where was there a severe drought and high temperatures between 2000-2003
the Pinon Pines in America made the tress more susceptible to pine bark beetle attacks and in some areas 90% of the Pines died.
flooding definition
If the discharge is of sufficient quantity to cause a body of water to overflow its channel and submerge the surrounding land, flooding is seemed to have occurred.
When a river exceeds bank full discharge
A great flowing or overflowing of water, especially over land not usually submerged.
human causes of flooding
ploughing up and down slopes rather than around them channels the rainwater to the river faster
dams may burst which will cause excess water in river channels and flooding of large areas
if vegetation has been removed there is less interception and water will move to the river more quickly
deforestation- cutting down trees means there is less interception and absorption of rain - rain water quickly enters he river which can result in flooding
if there is a town on a floodplain storm drains will allow water to move into the river at a greater speed and so make flooding more likely
physical causes of flooding
impermeable rocks mean that rainwater cant soak into the rocks and so it flows more quickly to the river through the soil or over the surface
sudden rise in temp, rapid thaw of snow can happen- rivers unable to cope with amount of water and flood
hot dry weather for long period- soil becomes hard and water cant soak in when it rains- runs off surface into the river
river beds become silted up and make the channel smaller and more likely to food
steep valley slopes make rainwater run off rapidly into the river channel
main human causes of flooding
changing land use within a river catchment
mismanagement of rivers using hard engineering
deforestation/vegetation removal
urbanisation
main physical causes of flooding
intense storms leading to flash flooding
heavy or prolongued rainfall
extreme monsoon rainfall
snowmlet
what does the Intergovernmental Panel on climate change (IPCC) predict
considerable changes to the global hydrological cycle as a result of increasing green house gas contributions.
in the UK what does the Living With Environmental Change Network (LWEC) study
the latest scientific evidence to produce a report predicting the impact of climate change on the water cycle in the UK by 2050.
why is modelling climate difficult
Climate dynamics- the way the atmosphere, ocean, terrestrial, cryosphere and biosphere systems all interact with each other is only particularly understood.
As a result of telecommunications, in some instances it is difficult to distinguish between the impacts of oscillations such as ENSO and climate warming.
Global records are very incomplete; in many parts of the world there is insufficient depth or detail of evidence to establish reliable trends for the impact of climate change or to make firm predictions about the future.
what do decision makers involved in water planning and disaster management have to factor
have to factor in the possibility of more extreme weather events but there is no definite link yet to be made to global warming.
effects of climate change on inputs and outputs in the hydrological cycle
increase in evaporation
more frequent short droughts
more flash floods in urban areas
increases in high flows and flooding
river qualities decrease because of higher water temps and increased sediments
decrease in recharge and lower groundwater levels
increasing river water temp
decrease in summer flows
according to the UN what rate has water use been growing at
water use has been growing at more than twice the rate of population increase in the last century and by 2025 1.8 billion people will be living in absolute water scarcity and 2/3 of the worlds global population will be living under water stress conditions.
what % of the worlds population live in areas recieving only % of the worlds annual rainfall
66% of the worlds population live in areas receiving only 25% of the worlds annual rainfall.
what is water security
The capacity of a population to safeguard sustainable access to adequate quantities of acceptable drinking water for sustaining livelihoods, human wellbeing and socio-economic development, for ensuring protection against water borne pollution and water-related disasters, and for preserving ecosystems in a climate of peace and political stability.’
patterns of water shortages across the globe
renewable water resources
water stress
water scarcity
absolute water scarcity
renewable water resources
countries experience water stress if renewable water resources are between 1000 and 1700m3 per capita
symptoms are widespread and include frequent and serious restrictions on water use, growing tension and conflict between users and competition for water, declining standards of reliability and service and harvest failures and food insecurity
water stress
countries experience absolute water scarcity if their renewable water resources are very low, less than 500m3 per capita
this situation leads to widespread restrictions on water use and rationing
water scarcity
the long term annual average total of internal and external renewable water resources
internal resources are the discharges of rivers and the recharge of aquifers generated from precipitation
external resources are are those generated outside a country and they include inflows from upstream countries and parts of a water body (lake or river) divided by a border
absolute water scarcity
countries experience water scarcity if their renewable water resources are low
between 500 and 1,000 m3 per capita
symptoms include unsatisfied demand open tension and conflict between users competition for water, over extraction of groundwater and insufficient flows to the natural environment
what physical factors lead to drought
unpredictable rainfall
poor aquifer recharge
thermal pollution
over abstraction
saltwater encroachment
what has the United Nations Water Development Report 2015 projected
an increase in global water demand of 55% by 2050.
what % of global water deficit has the UN projected by 2030
40%
how many people in the world rely on only reducing groundwater groundwater levels
2.5 billion
what happens to 90% of waste water in developing countries
discharged untreated directly into rivers, lakes or oceans.
which human activity has the largest use of water
agriculture
70% globally
90% in developing countries
what % of the worlds aquifers are over exploited
20%
huge depletions seen in areas like the North China Plain and in megacities like Beijing.
what did the Food and Agriculture organisation identify as the three dimensions of water scarcity
Availability- physical scarcity of clean freshwater resources to meet demand
Access – scarcity due to the failure of institutions to ensure a reliable water supply through water management
Utilisation- scarcity arising from inadequate infrastructure to use water resources due to financial constraints.
what did the Water stress index release
released by risk analysis and mapping firm Maplecroft, pinpoints areas of water stress down to 10km² worldwide by calculating the ratio of domestic, industrial and agricultural water consumption, against renewable supplies of water from precipitation, rivers and groundwater. It has been developed for companies to identify risk of water interruptions to supply chains, operations and investments.
why does water play a central role in economic development
Agriculture absorbs two-thirds of water extractions globally but industrial use is growing, especially in emerging countries such as China and India. The energy industry also requires water and just like in industry there are serious concerns about their environmental impacts as well as the waste discharge from these activities.
where is global demand for economic activities increasing
particularly in manufacturing where demand is expected to increase by 400% between 2000 and 2050.
what type of agriculture has expanded in recent years
fish farming has also expanded rapidly in recent years as wild fish stocks have declined. This has provided employment and economic growth but at the same time the lack or regulation of these markets has lead to the degradation of environments.
how are some crops grown
Some crops are grown under rain fed conditions, using green water in the soil and some are grown under fully irrigated conditions.
what % of the worlds land is under full irrigation
20%
what are the two types of irrigation methods
In water short areas there has been traditional irrigation methods for example along the River Nile. Industrial size irrigation which began in the 1960s using high yield variety seeds combined with fertilisers and pest controls has improved food scarcity dramatically but causes environmental concern:
what environmental concerns has industrial size irrigation caused
Irrigated land can become water logged and salinised
So much water is abstracted that groundwater has become severely depleted, especially in China, the USA and India.
eg of how the meat industry can impact water
In China the meat industry is also having a huge impact on water. It takes 2975 litres of water to make 1kg of rice and 17850 (x6) litres to create 1kg of beef.
what % of fresh water withdrawal worldwide is for energy production
20%
Rapid industrialisation in many areas of the world such as China and South Korea has contaminated rivers and groundwater. Some progress has been made by TNCs such as Coca-Cola India to reduce their consumption by recycling as well as introducing effluent controls.
eg of a country heavily reliant on HEP
New Zealand which rely heavily on HEP seasonal changes in precipitation heavily influence energy production. Water is also frequently used to cool nuclear power stations which can lead to thermal pollution .
industry and energy impacting on water
A further area of concern is the growth of biofuels, the crops used to create bioethanol and biodiesel are very thirsty; up to 10,000 litres of water is needed to create 1 litre of bioethanol and 20,000 litres for one litre of biodiesel.
water supply and human wellbeing
some huge improvements have been made in water sup0ply and quality around 15% of the worlds population still reply on unimproved water (unprotected wells, springs or rivers). Around 2.5 million people have no access to sanitation facilities. Diseases like cholera, typhoid and dysentery are contracted from drinking dirty water and the water acts as breeding ground for malarial mosquitoes, snails and worms.
why may water conflict occur over water resources
Conflict may occur over local water sources or over transboundary water- where a river, lake or aquifer crosses one or more political boundaries. According to the UN water, approximately 40% of the worlds population lives within river or lake drainage basins that extend over 2 or more countries.
what are the players in water conflict
political
business (economic)
social (human welfare)
environmental (sustainable development)
political stakeholders in water conflict
International organisations such as the UN who are responsible for the MDGs, government departments such as DEFRA, regional and local churches, lobbyists and pressure groups that fight against particular issues, for example the construction of mega-dams.
economic (business) stakeholders in water conflict
The World Bank and IMF which fund mega projects and ensure legislation in in place fro trans-boundary schemes, trans-national water companies and run the supply businesses. TNCs and large business users.
social (human wellfare) stakeholders in water conflict
Individuals, residents, consumers, farmers, landowners who feel access to water is a human right. NGOs such as water aid who provide and develop sustainable schemes for the poor in LDCs.
environmental (social development) stakeholders in water conflict
Conservationists who fight hard-engineering schemes or seek to save wetlands; scientists and planners who develop new schemes and try to influence water policy.
hard engineering
Hard engineering schemes use artificial structures to increase water supply, including water transfer projects such as China’s South-North Water Transfer, mega dams such as Ethiopia’s Gilgel Gibe Dam and desalinisation plants.
what % of the worlds major rivers are impended by dams
nearly 60%
In 2010 there were 845,000 dams in the world, 5,000 of which are mega dams.
what % of the worlds irrigated areas suffer from salinity problems and redemation is seen to be very costly
30%
in 2002 how many desalination plants were there
12,500 around the world
in 120 countries
how many cubic metres of freshwater did desalination plants produce in 2002
14 milllion
less than 1% of total world consumption
where are the most important users of desalinated water
the Middle East, (mainly Saudi Arabia, Kuwait, the United Arab Emirates, Qatar and Bahrain), which uses about 70% of worldwide capacity; and in North Africa (mainly Libya and Algeria), which uses about 6% of worldwide capacity.
which industrialized countries are the most important users of desalination
the United States is one of the most important users of desalinated water, especially in California and parts of Florida. The cost of desalination has kept desalination from being used more often.
Some of this information came from the Water Education Foundation and from the Corpus Christi TAMU-CC Public Administration
why are sustainable water schemes less controversial
they aim to balance economic, social and environmental needs by working with local people to develop soft engineering projects that work with natural processes to restore water supplies, and often including water conservation.
what does the UN suggest about sustainable water management
The UN Water organisation suggest and advocate the use of natural infrastructure; using the forests, wetlands and floodplains as water management solutions.
sustainable water management schemes
wetland restoration
riparian buffer
permeable pavements
water harvesting
green spaces
marsh/mangrove/dune/coast protection
wetland construction
flood bypass
afforestation
