Introduction
Water is an essential component of life on Earth, playing a critical role in biological processes, ecosystems, and human society. In this study note, we will explore the availability and consumption of water, the properties of water, and its role in living organisms as per the International Baccalaureate (IB) Biology syllabus.
Availability & Consumption of Water
Earth's Water Distribution
- Total Water on Earth: Approximately 97.5% of the Earth's water is saline, found in oceans and seas.
- Freshwater: Only 2.5% of the Earth's water is freshwater. This small fraction is crucial for all terrestrial life forms.
Freshwater Distribution
- Cryosphere: About 68.6% of freshwater is locked in the cryosphere as ice.
- Groundwater: Approximately 30.1% of freshwater is found as groundwater.
- Accessible Freshwater: Only about 0.9% of the Earth's total freshwater is readily accessible to humans.
Global Availability of Freshwater
Factors Affecting Water Quantity
- Rates of Rainfall: The amount of precipitation directly influences the availability of surface and groundwater.
- Groundwater and River Flows: The natural movement of water through rivers and aquifers affects regional water supplies.
- Transpiration: The process by which plants release water vapor into the atmosphere.
- Evaporation: The conversion of liquid water into vapor, which can lead to water loss from reservoirs and soil.
Water Management
Sustainable Management Approaches
- Water Saving:
- Reduce Bath Water Usage: Taking shorter showers and using water-efficient fixtures.
- Fix Dripping Taps: Preventing water wastage by repairing leaks.
- Efficient Use of Appliances: Operating dishwashers and washing machines only when full.
- Automatic Taps: Installing taps that turn off automatically to minimize wastage.
- Customer Pricing:
- Water Meters: Charging for water based on usage to incentivize conservation.
- Regulating Authorities: Ensuring competition among water providers to prevent monopolies.
- Water Purification:
- Disinfection: Using chlorine or other disinfectants to kill harmful microorganisms.
- Filtration: Removing suspended solids and contaminants through sand filters or light filtration.
Water management is crucial for ensuring equitable access to clean water, especially in regions facing water stress.
Patterns and Trends
- Access to Drinking Water: Since 2000, 1.8 billion people have gained access to basic drinking water services.
- Inequalities: Despite progress, significant inequalities remain in access to clean water, particularly between urban and rural areas.
