EARTHSCI-LESSON-4-WATER-RESOURCES

Chapter 4: Water Resources

Learning Objectives

  • Understand the hydrologic cycle concepts.

  • Explain Earth's water distribution.

  • Identify various water resources.

  • Discuss the impact of activities on water quality.

  • Recommend conservation and protection strategies for water resources.

Essential Questions

  • How does water cycle through Earth’s components?

  • What is the distribution of water on Earth?

  • How can we care for water resources?

The Hydrologic Cycle

  • Definition: Movement of water across Earth's surface and subsystems.

  • Key Components:

    • Reservoirs: Locations where water is stored for varying periods.

    • Pathways: Processes facilitating water movement between reservoirs.

  • Functions: Maintains total water quantity; energy from the sun drives the cycle.

Water Cycle Processes

  • Evaporation: Transition from liquid to vapor, mainly from oceans (80%), surfaces, and vegetation.

  • Sublimation: Ice converts directly to water vapor.

  • Condensation: Vapor cools to form clouds.

  • Precipitation: Water falls as rain, snow, or hail when droplets become heavy.

  • Infiltration and Run-off: Water permeates the land or flows over surfaces.

Water Distribution on Earth

  • Total Water Composition:

    • Oceans: 96.5% (saltwater)

    • Freshwater: 2.5%

      • Glaciers: 68.7%

      • Groundwater: 30.1%

      • Surface water: negligible amounts.

  • Residence Time: Duration a water molecule spends in a reservoir.

Types of Water Resources

  • Saltwater Reservoirs:

    • Oceans as significant saline bodies (largest reservoirs).

    • Salinity maintained through natural cycles.

  • Freshwater Reservoirs:

    • Glaciers and ice sheets hold most accessible freshwater.

    • Includes groundwater and surface water such as streams, lakes, and wetlands.

Groundwater Characteristics

  • Largest liquid freshwater reservoir, constituting 30.1% of total freshwater.

  • Aquifers: Water-bearing rock layers (high porosity in loose materials).

  • Recharge Zone: Areas where water replenishes underground supplies.

Impact of Human Activities on Water Quality

  • Overexploitation: Population growth leads to resource depletion and water quality decline.

  • Pollution: From various sources, significantly affects natural habitats and ecosystems.

  • Natural Events: Climate change and severe weather also impact water quality and availability.

Water Resource Management and Conservation

  • Strategies:

    • Planning and optimal use of water resources.

    • Rainwater harvesting and building of dams.

    • Improve water quality through treatment and reuse mechanisms.

Policies and Laws in the Philippines

  • Various laws aimed at water resource management and ensuring sustainable practices:

    • National Water Resource Council Creation.

    • Water Code - comprehensive regulations on water use and conservation.

    • Clean Water Act - focuses on water quality management.