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

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

1. 1/2 billion people chronically short of water

2. 1/3 of world population short of water

   • Will become 45% by 2025

3. Who are the main users of water?

   • Agric - 69% of world's fresh water + is least efficient
     • To produce 1kg of beef is 10x more water costly than 1kg of rice
     • Irrigation least efficient use of water
       • Seepage, high rate of evaporation, salinisation
   • Industry - 21%
     • BRICs lead to biggest usage of water - 10%
     • More efficient than agric - unless it's paper
     • Issues = water quality + pollution
   • Domestic - 10%
     • Increase in meat consumption in Western diets
       • More costly than a vegetarian diet - requires more land, water and capital
     • Most MEDCs need 100,000 litres per person per year
       • African countries need less than 50,000
       • Global demand 2x every 20 yrs

4. Competing users for water in the Murray-Darling Basin:

   • Agriculture - 80% of basin - 40% of Australia food production
   • Domestic - 2 million population
   • Some industry

5. Consequences of human activities on water amount + quality of MDB?

   • Total flow at mouth reduced by 61%
   • Water ceases to flow at all 40% of the time due to devpt
   • Salinity increases downstream
   • 2019 - 2,750 gl will be returned to the basin
     • National plan needed for the basin to create a balance in water use
   • By 2024 - further 450 gl to be gained

6. South-West Water (SWW), UK

   • Where does water come from?
     • 90% comes from surface water sources
     • 3 large reservoirs
       • Colliford
       • Roadford
       • Wimbleball
     • SWW aquifers limited - 10% of region water
     • Groundwater sources - Springs, wells, bore-holes - East Devon
     • During winter - abstracted from rivers and reservoirs as back up
     • Piping
       • Allows water transport in dry seasons
       • Pump water in reservoirs to avoid natural waiting period
   • How does SWW minimise leaks?
     • Use of mix of traditional leak detection methods
       • Listening sticks
       • remote monitoring
     • Flow-meters measure water passing through 750 geological zones
       • Calculates location of bursts + reduces potential lag between inspection of leak and arranging repairs
     • 2010 - Met leakage target 14th yr in a row
   • What is SWW doing to influence supply of water?
     • Upstream thinking
       • Env improvements to improve water qual
       • Land management observed so water quantity and quality improved at source
     • Dartmoor Mires project
       • Restoring bog at Winney's Down
       • Erosion threatening high qual blanket bog
       • Preserving wildlife + keep SW's potential as carbon sink + reduce climate change
       • Benefits?
         • Globally important habitat + species
         • Better water qual
           • Improves river life for species E.g. Salmon
         • Can slow surface run-off
         • Blanket bog will protect peat - Huge carbon sink
           • Protect further loss of carbon
   • Climate change adaption
     • Successful trial on Exmoor - 250 acres of mires restored
       • Permission for 4,000 more acres
     • Diffusing pollution
       • Attempt to prevent soils + fertilisers entering watercourse
       • Rainwater stores on farms + providing soil analysis to educate farmers on use of pesticides + fertilisers
       • Work with many environmental agencies to deliver 'Upstream Thinking' across Devon, Cornwall and West Somerset
   • Managing water resources in a changing climate
     • 1996 drought - heavy investing in water since
     • 2 Chinese clay pits turned into new water reservoirs
     • New pipelines
       • Leakage reduced 40%
       • Ability to transport water improved
     • Pumping stations to store water in winter
     • Increased capacity of treatment works