2.2 - How do human activities influence the supply and demand of water?

1/2 billion people chronically short of water
1/3 of world population short of water
1. Will become 45% by 2025
Who are the main users of water?
1. Agric - 69% of world's fresh water + is least efficient
  1. To produce 1kg of beef is 10x more water costly than 1kg of rice
  2. Irrigation least efficient use of water
    1. Seepage, high rate of evaporation, salinisation
2. Industry - 21%
  1. BRICs lead to biggest usage of water - 10%
  2. More efficient than agric - unless it's paper
  3. Issues = water quality + pollution
3. Domestic - 10%
  1. Increase in meat consumption in Western diets
    1. More costly than a vegetarian diet - requires more land, water and capital
  2. Most MEDCs need 100,000 litres per person per year
    1. African countries need less than 50,000
    2. Global demand 2x every 20 yrs
Competing users for water in the Murray-Darling Basin:
1. Agriculture - 80% of basin - 40% of Australia food production
2. Domestic - 2 million population
3. Some industry
Consequences of human activities on water amount + quality of MDB?
1. Total flow at mouth reduced by 61%
2. Water ceases to flow at all 40% of the time due to devpt
3. Salinity increases downstream
4. 2019 - 2,750 gl will be returned to the basin
  1. National plan needed for the basin to create a balance in water use
5. By 2024 - further 450 gl to be gained
South-West Water (SWW), UK
1. Where does water come from?
  1. 90% comes from surface water sources
  2. 3 large reservoirs
    1. Colliford
    2. Roadford
    3. Wimbleball
  3. SWW aquifers limited - 10% of region water
  4. Groundwater sources - Springs, wells, bore-holes - East Devon
  5. During winter - abstracted from rivers and reservoirs as back up
  6. Piping
    1. Allows water transport in dry seasons
    2. Pump water in reservoirs to avoid natural waiting period
2. How does SWW minimise leaks?
  1. Use of mix of traditional leak detection methods
    1. Listening sticks
    2. remote monitoring
  2. Flow-meters measure water passing through 750 geological zones
    1. Calculates location of bursts + reduces potential lag between inspection of leak and arranging repairs
  3. 2010 - Met leakage target 14th yr in a row
3. What is SWW doing to influence supply of water?
  1. Upstream thinking
    1. Env improvements to improve water qual
    2. Land management observed so water quantity and quality improved at source
  2. Dartmoor Mires project
    1. Restoring bog at Winney's Down
    2. Erosion threatening high qual blanket bog
    3. Preserving wildlife + keep SW's potential as carbon sink + reduce climate change
    4. Benefits?
      1. Globally important habitat + species
      2. Better water qual
        Improves river life for species E.g. Salmon
      3. Can slow surface run-off
      4. Blanket bog will protect peat - Huge carbon sink
        Protect further loss of carbon
4. Climate change adaption
  1. Successful trial on Exmoor - 250 acres of mires restored
    1. Permission for 4,000 more acres
  2. Diffusing pollution
    1. Attempt to prevent soils + fertilisers entering watercourse
    2. Rainwater stores on farms + providing soil analysis to educate farmers on use of pesticides + fertilisers
    3. Work with many environmental agencies to deliver 'Upstream Thinking' across Devon, Cornwall and West Somerset
5. Managing water resources in a changing climate
  1. 1996 drought - heavy investing in water since
  2. 2 Chinese clay pits turned into new water reservoirs
  3. New pipelines
    1. Leakage reduced 40%
    2. Ability to transport water improved
  4. Pumping stations to store water in winter
  5. Increased capacity of treatment works

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2.2 - How do human activities influence the supply and demand of water?

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