5.9a Technofix of hard engineering schemes

• Positives of mega-dams

  • contributes to 8-12% of global energy mix (HEP)
  • renewable - less reliant on fossil fuels
  • can be used for domestic, industry and agriculture
  • can create multiplier effect w/ jobs etc.
  • reduces water insecurity (may increase it downstream)
• Negatives of mega-dams

  • Disputes and political challenges between nations e.g Grand Renaissance Dam
  • very expensive
  • seismic activity - 20 earthquakes caused by Three Gorgers, highest was 6.1
  • flooding in local land
  • displacement of people
• Sustainability of mega-dams

  • renewable - reduces coal reliance due to HEP but methane is released (more potent)
  • 60% of world's major rivers impeded by dams
  • Yangtze dolphin extinct due to Three Gorges - decreasing biodiversity and disrupting ecosystems
  • flush sediment occasionally -> have to wait to fill up again in which HEP is not produced - insecurity and reliance
  • causes uncontrolled floods and increased erosion due to strength of water and sediment load.
• Grand Renaissance Dam

  • flooded 1680km2 of forest in North East Ethiopia
  • displace 20,000 people
  • $5-8billion cost
  • hold approx 70billion m3 of water - entire annual flow of Blue Nile at Sudan border
  • filling of dam will reduce water supply to Egypt by 1/3 and reduce arable land - loss of US$ 51 billion
  • 12,000 jobs
  • Egypt relies on Nile for 95% of water usage
  • potential for conflict
• Three Gorges Dam costs

  • $25 billion approx cost
  • Yangtze Dolphin extinct due to construction
  • 632km2 land flooded
  • 13 cities submerged between Dam and Chongqing
  • 2 million people displaced
  • low water quality due to water pollution
  • decomposing vegetation produces methane
  • 18 earthquakes caused (6.1 highest)
• Three Gorges Dam benefits

  • reduces risk of water shortages in Beijing
  • generates large quantities of electricity -> moving away from coal reliance
  • regulates water flow
  • architectural significance - tourist attraction and symbol of power
  • 5000 jobs created in area -> however jobs also lost due to displacement
• Positives of water transfers

  • diverts water from one drainage basin in surplus to another in deficit
  • reduces water insecurity and solves existing demand
  • improved human health due to better sanitation
• negatives of water transfers for source area

  • less water may increase water poverty
  • ecosystem changes - degraded land, lower functioning and productivity due to decreased water supply
  • pollution - less opportunity for dilution so pollutants more concentrated
• negatives of water transfers for receiving area

  • greater availability leads to greater use + waste
  • promotes/allows unsustainable irrigated farming e. g agribusinesses
  • eutrophication in water courses - polluted water transferred to other ecosystems and areas
  • development in tourism and recreation (social positive) but environmental negative due to water usage associated with it
• general negatives of water transfers

  • expensive building and maintenance costs
  • leakage in pipes - less effective
  • increased stress in source area
  • current issue solved but may fail in future
• Costs of China's South-North Water transfer

  • $US 70 bil
  • submerge 370km3 of land - water level raised 13 metres due to construction
  • 300,000 people displaced
  • water quality at risk due to industrial pollution, particularly Eastern route
  • Yangtze basin already polluted - Yellow River undrinkable and scientists fear ecological disaster
  • Increase water stress in South
• Benefits of China's South-North Water transfer

  • reduces risk of water shortage in Beijing
  • boost economic development -> show of strength to TNCs, multiplier effect
  • reduces abstraction of groundwater (water table in Beijing fell 300 metres since 1970s)
• positives of desalination plants

  • provides a reliable and predictable supply of water
  • sustainable process
• negatives of desalination plants

  • expensive
  • salt waste can damage marine ecosystems
  • process uses large amounts of energy
• desalination plants

  extracts salt + solids in seawater to enable it to be used for drinking and irrigation
• Israel's desalination project

  • five plants were opened by 2013, taking water directly from the Mediterranean
  • filtered water put under high pressure by reverse osmosis
  • provides over 55% of Israel's domestic water
• Pros of Israel's desalination project

  Produces up to 600 tonnes of potable water per hour
• Cons of Israel's desalination project

  • each plant requires its own power station and adds to CO2 emissions - much of energy used is solar
  • produces vast amount of salt/brine which contains anti-scaling agent