Hydrosphere
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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/urbanisation • increased affluence causing increased use per capita • increased irrigation • industrialisation • climate change • pollution • climate change • ‘virtual-water’ and ‘Western Diet’ use increase
Why is population growth/urbanisation 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, urban areas need more water but infr. may be poor • more people also need more food, so increased irrigation