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Lecture 8 part 2 Water Resources in the Hydrosphere

The Hydrosphere

  • Fresh Water: Only 2.5% of the Earth’s water is fresh; most is trapped in glaciers and ice caps.
    • Surface Water: Of fresh water, only 1% is surface water found in lakes and soil moisture.

World Water Distribution

  • Salt Water: 98% of Earth's water is salt water.
  • Fresh Water: 2% consists of fresh water which is divided as follows:
    • Ice: 87% of fresh water is in ice form.
    • Groundwater: 12% found beneath the Earth's surface.
    • Rivers and Lakes: Only 1% of fresh water.

Fresh Water as a Limited Resource

  • Static Quantity: Absolute quantities of fresh water remain roughly constant over time.
  • Challenges:
    • Uneven distribution causes accessibility and availability issues.
    • Factors influencing availability:
    • Precipitation levels in a region.
    • Presence of rivers, lakes, and groundwater stores.
    • Human consumption needs and water demands.

Unequal Global Distribution of Fresh Water

  • In 2000:
    • Countries with Least Fresh Water: Egypt, UAE.
    • Countries with Most Fresh Water: Suriname, Iceland.
  • Average river flows and groundwater recharge varied significantly across regions.

Water Stressed Areas

  • About 40% of the global population lived in water stressed areas, projected to rise to 50-65% by 2025.
  • By 2050, nearly half of the global population will be in water-scarce regions.

Hydrologic Cycle

  • Key Components:
    • Precipitation: Water falling from the atmosphere.
    • Runoff: Water flowing over land to lakes and rivers.
    • Evaporation: Water converting from liquid to vapor.
    • Transpiration: Release of water vapor from plants.
    • Percolation: Movement of water through soil layers.

Great Lakes

  • Largest fresh water body on Earth, 1/5 of the planet's surface fresh water.
  • Home to 34 million people and over 3,500 species, including numerous fish.

Groundwater

  • Aquifers: Saturated zones underground where water accumulates.
  • Water tables are lowering due to extraction rates exceeding natural replenishment.
  • Major aquifers exist across Canada and the U.S., including different saturated thicknesses.

Wetlands

  • Types of wetlands include: Swamps (with trees), Marshes (with grasses), and Bogs/Fens (waterlogged soils).
  • Wetlands provide habitat, filter contaminants, and store water.
  • Prairie Potholes in Canada serve vital nesting sites for waterfowl.

Water Use and Withdrawal

  • Water Withdrawal: Removal/diversion of water followed by its return to the source.
  • Consumptive Use: Permanent removal of water not returned to the environment.
  • Instream Use: Use of water while it remains in its original source.

Global Water Withdrawal by Sector

  • Total annual water withdrawal globally is approximately 3,414 km³.
  • Significant percentages are used for agriculture and industry in various regions.

Water Pollution

  • Nutrient pollution leads to eutrophication.
  • Point sources include direct discharges from facilities. Non-point sources include runoff from agricultural and urban areas.
  • Major polluters: fertilizers, toxins, sediments affecting water quality.

Water Treatment

  • Techniques include end-of-the-pipe treatment (chlorination), artificial wetlands, and phytoremediation.
  • Effective for purifying contaminated water supplies.

Climate Change Impact on Water Resources

  • Climate change is expected to shift rain patterns, cause earlier snowmelt, and result in prolonged dry spells.
  • Droughts may become more frequent and severe in certain regions.

Desalination

  • Process of removing salt from seawater to create freshwater.
  • Used primarily in water-scarce regions, particularly the Middle East.
  • Expensive but crucial for regions like Saudi Arabia where 70% of global capacity is utilized.

Canadian Water Regulations

  • Agreements like the Great Lakes Water Quality Agreement and Ramsar Convention aim to protect water resources.
  • Issues of water exportation and management of shared water basins highlighted by legislative efforts.

Closing Notes on Water Conservation and Management

  • Emphasizes the importance of sustainable practices in agriculture, industry, and domestic use.
  • Recognizes water as a vital yet limited resource, necessitating strategic conservation efforts and efficiency measures across all sectors.