Hydrosphere Flashcards
What are the three main human uses of water? What are the % totals?
Agriculture 70%
Industry 22%
Domestic use 8%
What is the major water consuming activity of Agriculture?
Irrigation
What is the global differences for HICs/LICs in terms of agriculture water use?
HICs:
- irigation is mechanised e.g. sprinkler, timed feeds
- lots of water available for agricultural areas
LICs:
- irrigation channels
- water loss through evaporation
What are the major water consuming activities for industry?
cooling
heating
washing
solvent
What is the global differences for HICs/LICs in terms of industry water use?
HICs:
- large scale
- large amounts of water needed
e.g. steel
LICs:
- smaller scale cottage industries
- less water demand
- BUT MNC location in developing countries raises demand
e.g. India’s drinks manufacturing needs over 1 million litres a day
Give 2 examples of water need for common products
17,196 litres/kg chocolate
1608 litres/kg bread
What are the major water consuming activities in domestic use?
Flushing toilets
Hygiene
Washing clothes, dishes
What is the global differences for HICs/LICs in terms of domestic water use?
HICs:
- lots of facilities requiring water use
e.g. toilets, showers, baths, washing machine, swimming pools…
- UK person uses 142L a day
- 100% uses improved water supply
LICs:
- many people do not have access to piped water
- they may collect it and bring it home from a well or stream (disease?)
- they use it sparingly
- Sudan person uses less than 6L a day
19.3% rural pop uses unimproved water sources
2 billion people do not have access to safe water
What percentage of the world’s water is held in:
a) the ocean (salt)
b) freshwater
a) 97.5%
b) 2.5%
What are the three forms water takes?
- solid (ice, snow)
- liquid (oceans, rivers lakes, rain)
- gas (water vapour) in atmosphere
Why is water referred to as a renewable resource?
- the processes of the water cycle is constantly renewing the surface water and groundwater stores
- precipitation feeds rivers and streams, and also infiltrates into the ground to replace water we use
What is the natural hydrological cycle?
the continuous movement of water between rivers, oceans, the atmosphere and the land (storage reservoirs)
Why is the natural hydrological cycle a closed system?
Because there is as much water as there will ever be - there is no external factor which can change that
What do we mean when we refer to the natural hydrological cycle being in dynamic equillibrium?
the amount of water in circulation does not change and each storage reservoir remains constant over long periods of time as the processes cancel each other out
What is residence time?
the average length of time water stays in a reservoir (auifers, oceans etc) before moving into another reservoir
How do we calculate residence time?
residence time = volume of water/rate of transfer
What 2 main processes drive the hydrological cycle?
- Solar energy
- provides the energy for evaporation - Gravitational/Potential energy
- the downwards movement of precipitation
Give 4 properties of liquid water that is useful for life
- stays liquid over huge temp range
- anomalous expansion
- thermally stable + excellent solvent
- high spec heat capacity
Why is the state of water as a liquid important?
- essential for metabolism
- useful for aquatic organisms which avoid freezing
Why is it important that water is both thermally stable and an excellent solvent?
- ideal for chemical reactions
- all enzyme reactions e.g. photosynthesis occurs in solution
Why is high specific heat capacity of water important?
- it requires a lot of energy to raise water temperature, and so a lot can be lost before water temp falls
- so can regulate climate and reservoir temperature stability
Why is anomalous expansion important?
- water most dense at 4 degrees and freezes top down
- the ice crust forming on the top of the water body insulates the water underneath
What factors are causing global water demand to increase?
- population growth
- increased affluence causing increased use per capita
- increased irrigation
- industrialisation
- climate change
Why is population growth increasing the global demand for water?
- increased birth rate/immigration means more people need to use water
- urban pop expected to more than double 1995-2025
- more people also need more food,so increased irrigation
Why is increased affluence (leading to increased use per capita) increasing the global demand for water?
- more money can be spent on washing and appliances that use more water e.g. swimming pools, washing machines, despite modern water-saving machines
- in poor communities, domestic use may be limited to how much you can carry
Why does increased irrigation lead to increased water demand?
- subsistence farming relies on natural water availability, and so will adapt to different types of farming if water is unavailable e.g. nomadic herding vs arable farming
- expansion of commercial agriculture increases income that can be invested in irrigation schemes, which may pump water from storage reservoirs
- irrigation now uses more water than all other human uses combined
Why does industrialisation increase water demand?
-heavy industry such as chemical and steel industries or paper making use lots
- service industries use little except for domestic workers
Why does climate change increase water demand? (Lots)
- hotter summers = drier land
- more water needed for irrigation, domestic, agriculture, drinking etc
- disrupts precipitation
- rising sea levels = salinisation of groundwater
- glacier melt that previously was a water supply
-droughts/floods spread disease
What is ‘water withdrawn’?
the total volume removed a water source e.g. lake, river
- a portion of this water may be returned to its source to be used again e.g. hydroelectric power
What is ‘water consumed’?
Give an example
the amount of water removed for use and not returned to its source e.g. agricultural irrigation
What does the water AVAILABILITY look like in the UK?
NW = more water, less people, less demand
- lots of water available
SE =less water, more people, growing pop, more demand
- insufficient water available
Greatest demand: summer
Greatest demand: winter
Storage reservoirs and transfer schemes
What does the changing water situation look like in the UK?
household demand will increase
non household will decrease
15L used per day for drinking water and food prep - out of 142L, that’s a lot of time and money wasted on treatment.
What are the human impacts on the hydrological cycle?
deforestation
agriculture
urban development
global climate change
What impact is deforestation having on the hydrological cycle?
- vegetation intercepts rainfall that then may evaporate before it reaches the ground
- tree roots take up water from the soil
- without trees there will be lower rainfall downwind as more water infiltrates ground/flows into streams
What impact is agriculture having on the hydrological cycle?
Water does not infiltrate easily into soil compacted by heavy machinery/livestock
- soil moisture decreases
- runoff increases
Irrigation increases evaporation
Loss of soil biota (e.g. worms) reduces infiltration, increases runoff, reduces water retention
What impact does urban development have on the hydrological cycle?
Increased impermeable surfaces (concrete, tarmac)
- increased runoff/flooding
- reduced infiltration
What are the impacts of global climate change on the hydrological cycle?
Higher global temps
- affect rates of melting/evaporation/condensation/wind patterns
- all affects precipitaion rates/times/location
Rapid snow/ice melt
- normally reduces extremes, when falls seasonally
- now, melt just increases flooding
What are aquifers?
rocks which hold water that is then exploited as a resource
What are the essential characteristics of aquifers?
High porosity
Permeability
Associated geological structures
What is porosity?
Why do aquifers need it?
Give an example of rocks that are porous
The measure of the proportion of a rock’s volume that is space that can hold water
So it can hold water
Chalk, limestone, sandstone
What is permeability?
Why does an aquifer need it?
Give a bad example
the measure of the ease with which water can flow through the rock because of the interconnections/size between pore spaces
So water can move through the pores and fissures
Clay is porous, but the pores are too small for water to flow through easily
What associated geological features do aquifers require and why?
Impermeable rock below
- stopping the water draining out
Permeable rock above it
- allowing it to recharge
Why are aquifers a good option as a water source?
- cheaper than reservoirs
- no evaporation loss
- rainwater may take centuries to reach the water table, therefore it is usually clean so needs less treatment
How much of the UK’s water supply is from aquifers?
Why isn’t it more?
1/3
Because if we exploited all of them, the stuff on top would collapse
Why is recharge of aquifers important?
Consider:
a) precipitation recharge
b) ice age recharge
c) ancient aquifers
If the aquifer is recharged by rainfall percolating to the ground, abstraction can be sustainable if we do not exceed the recharge rate
If they are the aquifers recharged during the last ice age 10-20,000 years ago, they may not be getting recharged now and exploitation is unsustainable, and could lead to shortage
If they are ancient, their water if often saline and so when used for irrigation, they can cause soil salination (evaporation)
- osmotic dehydration/death of crops
What are the two types of aquifers?
Confined - covered on all sides by rock
Unconfined - partially exposed
How can we monitor aquifer depletion?
Why is it important?
- checking the level of the water table in wells or boreholes using electronic pressure sensors
- slow
- difficult to coordinate on a large scale - Satellite data to observe gravitational differences on the Earth’s surface
- GRACE
How does GRACE work?
- gravitational field is determined by features and topography including aquifers and groundwater on the surface
- satellite orbit is partially gravity determined
- changes in distance between twin GRACE satellites indicate changes in grav. field
- whole Earth surveyed every 30 days
What does GRACE stand for?
Gravity Recovery And Climate Experiment
How can we replenish aquifers?
- Reduce abstraction levels
- Alternative supply sources
- Recharging Aquifers
How can we reduce aquifer abstraction rate?
Industrial & Agricultural - licenses
Domestic - conservation
What alternative supply sources can replace aquifers?
Increasing capacity of other stores e.g. reservoirs
How can we recharge aquifers?
Give an example
Put water back into them
North London Aquifer Recharge Scheme (NLARS)
- tops up a chalk aquifer with treated water after heavy rainfall to use as a back up resource to boost supply during droughts
What effect can over-exploitation of rivers have for drinking water?
- water and food shortage
What effects can over-exploitation of rivers have for industry?
- high concentration of pollutants in the river
- loss of productivity and jobs
What effects can over-exploitation of rivers have for agriculture?
- not enough for irrigation
What strategies are implemented in water conservation?
- Low volume uses
- Recycling used water
- Pollution Control
- Reduced wastage
What methods are included within low volume water uses?
- Low-water appliances
- Xeriscaping
- Low-volume irrigation
How do low-water appliances contribute to low volume water uses?
Give examples
They limit the flow rate while maintaining a high water pressure, or use minimum water
- low flow shower heads
(10-15L/minute reduced to 6/8L) - dishwashers
- dual flush toilets
What is xeriscaping?
Managing parks/gardens/verges etc by planting them with more drought resistance vegetation so they require less watering
How does low-volume irrigation work?
drip irrigation delivers water directly to plants which leads to lower evaporation losses than overhead sprays
How do we recycle used water?
GREY WATER
- water that has already been used but is still quite clean can be reused e.g. bath water used to flush toilets/water gardens
Why do we need to implement water pollution control?
Can we treat it?
- many activities e.g. industry produce contaminated water which cannot be reused and may pollute other water sources such as rivers
- effluent treatment processes usually treat it
Give examples of water pollution control
- oil pollution treatment
- sewage treatment
- acid mine drainage
- heavy metal waste control
- landfill leachate treatment
- buffer strips next to rivers to reduce fertiliser runoff
Why is there a lot of water wastage in the UK?
- water infrastructure in poor condition
- 20% water intended for public supply is lost from leaking pipes
- leaking appliances e.g. taps
- fixed fees do not encourage careful use
- water consuming appliances
How can we reduce water wastage UK?
- repair and maintain leaks and breaks
- install water meters charging customers to pay to the volume of water used: less water will reduce the bill
What percentage of water usage in the home do toilets account for?
How can we reduce this?
30%
- don’t flush every visit
- install water displacement device reducing water per flush
- install dual/low flush
Give examples of how can we reduce personal water usage
- showers not baths
- use new/water saving appliances
- minimum kettle fill
- recycle water from washing
- collect gutter water/water butts
- xeriscaping
Why might water need treatment before use?
How many tests are there for UK drinking water?
natural problems
human problems
- 3 million tests - 99% pass
- 1% includes faecal coliforms, lead, pH etc…
Why is surface water stored in open storage reservoirs before treatment?
- dilutes contaminants from incoming water with pre-held water
- debris/sediments settle out
- sunlight breaks down organic material
- some bacteria die
What criteria does water have to pass to be deemed usable?
pH
Heavy Metals (e.g. lead)
Dissolved Oxygen
Calcium content
Cl2 retention
Turbidity
Pesticides
E. coli
Clostridium perfringens
