Lecture Notes: The Hydrosphere

Introduction

• Discussion on the hydrosphere: Earth's water resources.
• Importance of water as a resource and its major processes.
• Impact of human activity on the hydrosphere.

Water Distribution

• Over 70% of Earth's surface is water.
• Most water is saltwater, not usable by most organisms.
• Only a small fraction is freshwater, with much of it being frozen.
• Water is chemically unique, a universal solvent, holds temperature well.
• Essential for life: Most organisms are over 50% water by weight.

The Hydrologic Cycle

• Earth’s water is finite; water cycles naturally (hydrologic cycle).
• Surface Water to Atmosphere:
  • Evaporation: Liquid to gas, energy from the sun.
  • Transpiration: Plants losing water vapor, combined into evapotranspiration.
  • Evapotranspiration purifies water as it leaves dissolved substances behind.

Atmospheric Processes

• Condensation and Precipitation:
  • Water vapor cools, condenses into droplets, forms clouds.
  • Saturated clouds release water as precipitation.
  • These processes can pollute if the air contains pollutants (e.g., acid rain formation).

Precipitation and Water Fate

• Infiltration:
  • Water soaks into soil, reaches groundwater aquifer.
  • Generally purifying; soil filters and microorganisms break down pollutants.
• Runoff:
  • Water runs off surfaces, can cause pollution from surface contaminants.
• Groundwater:
  • Flowing towards oceans.

Ecosystems' Role

• Forests:
  • Reduce raindrop energy, prevent erosion, increase infiltration, purify water.
• Wetlands:
  • Act as sponges, hold water, allow for natural filtration and groundwater recharge.

Human Impact

• Loss of Forests and Wetlands:
  • Increases flooding, diminishes natural water filtration.
• Impervious Surfaces:
  • Paving increases runoff and pollution; prevents infiltration.

Watersheds

• Defined as land areas draining into a water body.
• Example: Chesapeake Bay watershed.
• Importance in pollution control across states influencing larger water bodies.

Water Usage

• Surface Water: Primarily for thermoelectric power.
• Groundwater: Mainly for irrigation, raising concerns about pollution and inefficiency.

Solutions and Alternatives

• Electricity Production: Encouraging solar, wind, hydroelectric methods.
• Irrigation Improvements: Advocating for efficient drip irrigation over sprinklers.
• Responsible Landscaping: Using native plants, reducing water-inefficient landscapes.
• Recycling Water: Utilizing gray water for non-potable uses like gardening.
• Low Flow Fixtures: Reducing water use to save energy and resources in water treatment.

Conclusion

• Importance of reducing water usage and pollution.
• Encouraging practices such as turning off taps when not in use.