Water Security

• Sources of Water - Stores:

  • Surface water supplies (Rivers & Reservoirs) - 0.3% of fresh water.
  • Underground stores (Groundwater aquifers) - 30% of fresh water.
  • Seawater (After Desalination) - 97.5% of all water.
  • Cryosphere - 70% of all fresh water.
• Sources of Water - Consumption:

  • Agriculture accounts for 70% of all fresh water consumption.
  • 22% of all fresh water goes to industrial uses.
  • 8% of all fresh water is used domestically.
• Water Scarcity:

  • People living in areas of water scarcity are facing water shortages.
  • Water resources cannot meet the demands of the population.
  • Can be due to physical factors such as low precipitation or human factors such as over-abstraction.
  • Economic scarcity means the water is there but cannot be abstracted due to a lack of money.
• Water stress:

  • An internationally agreed term for areas where water availability is less than 1700m^3 per year.
  • Results from an imbalance between water use and the availability of water resources.
  • An area can be water stressed but not water scarce due to high levels of pollution.
• Water Stress - Fresh water supplies:

  • Water stress causes a deterioration of fresh water supplies.
  • Quantity -e.g. Overabstraction from rivers, reservoirs or aquifers.
  • Quality - e.g. Organic pollution or eutrophication of surface water or salt water incursion into aquifers.
• Hydropolitics - Berlin Rules on Water Resources:

  • Summaries international law customarily applied to sharing freshwater resources.
  • The rules require nations to take appropriate steps to sustain and manage water resources, minimising environmental harm.
  • Countries are encouraged to see water management as an opportunity for regional economic development to be strengthened.
  • 450 transboundary agreements that exist regarding international waters.
• Hydropolitics - Local Scale Conflicts:

  • Cambodia, Laos, Thailand and Vietnamn signed the Mekong Agreement in 1995 to form the Mekong River Commission.
  • This agreed to jointly manage the shared water resources and sustainable development of the lower Mekong Basin.
  • In 2016, Laos started construction of the Don Sahong Dan, a HEP project, just two miles north of the Cambodian border.
  • The dam threatens downstream fishing industries in Cambodia, Thailand and Vietnam.
• Relationship of Water Supply to Physical Geography - Climate:

  • Climate is the primary factor that influences water supply.
  • Low-pressure weather systems (tropical storms) can bring excessive levels of overland flow instead of infiltration, which may recharge groundwater stores and aquifers.
  • Summer precipitation is less effective at recharging water stores as ground tends to be harder, discouraging infiltration. Also loss of water from evapotranspiration.
  • Spring may bring increased snow melt.
  • More storms occur in autumn.
• Relationship of Water Supply to Physical Geography - Geology:

  • Impermeable surfaces, such as clay, will act as water-shedding surfaces, while porous rocks, such as chalk, will act as aquifers.
  • Alternating bands of hard and soft rock may lead to natural water gathering basins or synclines; when water is trapped within these - Atersian Basin.
  • Hard, resistant rock might lead to areas of upland and subsequent relief rainfall, On other slope a rain shadow may reduce precipitation totals.
• Relationship of Water Supply to Physical Geography - Drainage:

  • River systems with a higher drainage density and range of inputs are more efficient water gatherers than those that rely on one water source.
  • Without monitoring or controls, any water supply can become polluted from industry, agriculture or domestic uses.
  • Over-abstraction from groundwater and rivers can also cause ecological damage.
• Strategies to manage Water Consumption (California)- Domestic (Food Consumption):

  • Food is increasingly sourced from growing regions that do not suffer water stress, leading to changes to diets.
  • Rather than eating fruit and vegetables that are out of season (Spanish strawberries), they may need to rely more on home-grown vegetables (winter season sprouts) or those that are more drought or salt-tolerant (broccoli).
• Strategies to manage Water Consumption (California) - Domestic (Water Conservation):

  • Energy and water efficient dishwashers and washing machines use less water than washing by hand.
  • Greywater recycling and rainwater harvesting systems.
  • Watering gardens early or late in the day to reduce evaporation.
  • Using brooms instead of hoses to clean driveways and footpaths.
  • Using plants that need less and water and use mulch to retain moisture.
  • Shuti-off nozzle on hosepipes.
  • Dual flush tilets that use less water for each flush
• Strategies to manage Water Consumption (California) - Domestic (Water Meters):

  • Fitting a water meter means you only pay what you use.
  • This is a positive step towards reducing a water footprint because it forces people to think more about managing water consumption.
  • The average family in the UK reduces their water usage by 10-15% after a water meter is fitted.
• Strategies to manage Water Consumption - Agricultural:

  • Micro-irrigation is the most efficient method and employs low-flow technology to deliver water directly to plant roots at rates that prevent deep percolated, evaporation and run-off losses.
  • Drip feed irrigation - small irrigation heads that deliver to trickle directly at the plant base.
  • Soaker hoses - have small openings that allow water to seep out and are placed at plant bases for rows of crops.
  • Micro-sprayers - overhead sprinklers which deliver a fine mist that can be controlled.
• Strategies to manage Water Consumption - Alternative Agricultural Methods:

  • Using mulches wherever possible to retain water content.
  • Collecting stormwater and irrigation run-off in ditches or drains.
  • Minimal or no ploughing.
  • Contour ploughing to reduce run-off.
  • Organic fertilisers to retain soil moisture.
  • Using cover crops in winter and fallow times to improve the soil and reduce water loss and soil erosion.