Water Resources in Pacific Islands - Summary Lecture Notes

6.1 Facts About Water

• Water is a unique substance:
  • Exists in three states: solid, liquid, and gas.
  • Universal solvent: dissolves substances, transporting nutrients and minerals.
  • Availability determines land cultivation and settlements.

6.2 The Hydrological Cycle

• Earth's water is constantly circulating in a global system called the Hydrological or Water Cycle.
• The cycle collects, purifies, and distributes Earth's water supply.
• Driven by solar energy and gravity.
• Solar energy evaporates water from oceans, streams, lakes, soil, and vegetation.
  • 84% of atmospheric water vapor comes from oceans (covering 70% of Earth).

Hydrological Cycle Processes

• Precipitation: Water falls onto the Earth's surface.
• Evapotranspiration: Water returns to the atmosphere via evaporation from surfaces and transpiration from plants.
• Infiltration and Percolation: Water seeps into the soil, becoming groundwater.
• Run-off: Water moves over land, joining oceans, then evaporates.
• Condensation: Water vapor cools in the upper atmosphere, forming water droplets.

Water Supply

• There is sufficient water globally, but regional shortages occur due to uneven distribution and limited accessibility.

6.3 Human Uses of Water

• Essential for:
  • Domestic/municipal use.
  • Industrial uses.
  • Agriculture.
  • Urbanization.
  • Power generation.
• Population growth increases water demand.
• Water shortage is a major problem in Asia, Africa, and the Pacific, necessitating water management strategies.

6.4 Water Problems

Water Shortage

• Causes: dry climate and overpopulation.
• Stresses on major river systems.
• 1 in 6 people lack regular access to clean water.
• Poverty restricts water access.
• Hydrological poverty is a concern.

Water Pollution

• Sources: stray animals, chemical pollutants from farms, sediments, deforestation.
• Saltwater intrusion contaminates freshwater sources.
• Rubbish dumping pollutes water.

Saltwater Intrusion

• Occurs when saltwater contaminates freshwater aquifers.
• Illustrated by a diagram showing a major irrigation well contaminated with saltwater and the normal interface between fresh groundwater and saltwater.
• Global warming exacerbates the issue, causing sea level rise.

Political/Tribal Boundaries

• Landlocked countries face water access issues.
• Conflicting tribal interests and boundaries complicate water management.

Global Warming

• Sea level rise contaminates low-lying atolls' freshwater lenses.
• Climate change leads to droughts or tropical cyclones, polluting water sources.

Other Problems

• The natural balance of the water cycle is disrupted by:
  • Deforestation.
  • Stream diversion.
  • Urbanization.
  • River pollution.

Strategies for Water Management

1. Increasing Freshwater Supplies

• Dams and reservoirs for storage.
• Sustainable groundwater extraction.
• Desalination (expensive).
• Reducing water waste.
• Catching precipitation (rainwater).

2. Reducing Water Waste

• 65-70% of water is wasted through evaporation and leaks.
• Water conservation benefits include reduced leakage and water savings.
• Increase water prices to disincentivize wastage.
• Government subsidies for water efficiency improvements.
• Improve irrigation techniques (low-pressure sprinklers, drip irrigation).
• Reduce water usage in homes and businesses.
• Irrigation Systems
  • Gravity Flow: (efficiency 60%-80% with surge valves). Water is sourced from aqueducts or rivers.
  • Drip Irrigation: (efficiency 90%-95%). Water is delivered directly to plant roots through pipes or tubes.
  • Center Pivot: (efficiency 80% with low-pressure sprinkler and 90-95% with LEPA sprinkler). Water is pumped from underground and sprayed.

3. Using Water More Sustainably

• Blue revolution: save water!
• Improve water security and management strategies, and ensure access to clean water and sanitation.
• Reduce water waste.
• Water prices should reflect true costs to prevent wastage.
• Implement drier waste treatment methods.
• Preserve forests.
• Slow population growth.

Individual Actions for Water Conservation

• Use water-saving toilets, showerheads, and faucet aerators.
• Take short showers instead of baths.
• Repair water leaks.
• Turn off the tap while brushing teeth or shaving.
• Wash full loads of clothes or use the lowest water-level setting.
• Wash cars with a bucket and use the hose only for rinsing.
• Use commercial car washes that recycle water.
• Replace lawns with native plants requiring little watering.
• Water lawns and gardens in the early morning or evening.
• Use drip irrigation and mulch in gardens.
• Use recycled (gray) water for watering and car washing.

Solutions for Water Pollution

• Prevent groundwater contamination.
• Reuse treated wastewater for irrigation.
• Find substitutes for toxic pollutants.
• Use natural methods for sewage treatment.
• Practice the four R's: refuse, reduce, recycle, reuse.
• Reduce resource and air pollution.
• Reduce poverty and birth rates.

Individual Actions for Reducing Water Pollution

• Use manure or compost instead of commercial fertilizers.
• Minimize pesticide use and avoid applying near water bodies.
• Grow or buy organic foods.
• Compost food waste.
• Avoid using water fresheners in toilets.
• Do not flush medicines down the toilet.
• Properly dispose of harmful chemicals, such as pesticides, paints, and solvents.

Pacific Island Countries

• Rainfall:
  • Low latitude countries (e.g., Kiribati, FSM, Tuvalu) experience low rainfall.
  • Oceanic islands lack rivers/streams, relying on groundwater and rain collection.
• Limited knowledge about water resources, especially water lenses.
• Poor water collection and storage infrastructure.
• Population increase strains limited water resources.
• Vulnerable to climate change and El Nino effects.

6.5 Sustainable Water Management in Small Island Countries

• Protect water sources from animals and chemical pollution.
• Use organic fertilizers.
• Control population growth and mobility.
• Implement centralized piping systems for treatment.
• Settle land disputes over water sources.
• Conduct community awareness and educational programs.
• Establish protected nature reserves to safeguard water catchments from disturbance and pollution.