Notes on Principles of Sustainability: Water
The Blue Planet - Water Composition - 70% of the Earth's surface is covered by water. - 97.5% of this water is saltwater; only 2.5% is freshwater.
Hydrologic Cycle - Water Recycling - The total volume of water on Earth remains constant, cycling through the environment.
Process: - Precipitation: Water falls from the atmosphere to the ground. - Surface Water: Water in rivers, lakes, etc. - Infiltration: Water percolates into the ground, replenishing groundwater. - Evaporation: Water returns to the atmosphere from the ground and surfaces.
Key Issue: Understanding water scarcity vs. water security and its implications.
Water Distribution - Uneven Access - Water availability varies significantly across different regions and populations.
Water Stress: Defined as the ratio of water withdrawals to supply. - Categories: - Low stress: <10% - Low to medium stress: 10-20% - Medium high: 20-40% - High: 40-80% - Extremely: >80% - These categories indicate the competition for limited water supplies.
Water Renewability - Renewable vs. Nonrenewable: Water can be both renewable and nonrenewable depending on its source and replenishment time: - Biospheric Water: 1 week - River Channels: 2 weeks - Lakes & Reservoirs: 10 years - Groundwater: 1,000 to 10,000 years
Threats to Water - Pollution: Contaminants affecting water quality.
Saltwater Intrusion: Movement of saltwater into freshwater areas due to excessive groundwater extraction. - Visual representation shows the gradient of freshwater to saltwater interactions.
Dams: Impact on natural water flow and ecosystems.
Consumption - Virtual Water: Amount of water embedded in the production of goods, e.g., - 3,000 gallons for a pair of jeans. - 1,500 gallons for 1 pound of beef.
Water Pricing: Heavily subsidized, leading to less incentive for conservation.