PYTR Class

Learning Objectives

1. Define water security and explain its importance in ensuring access to safe drinking water.
2. Analyse how social, cultural, economic, and political factors influence the availability and equitable distribution of freshwater resources.
3. Explain the relationship between population growth, economic development, and the need to increase water supply or improve water-use efficiency.
4. Identify and describe methods for increasing water supplies, including dams, reservoirs, rainwater catchment systems, desalination, and wetland enhancement.

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Part 1: Water Security

• Global Water Crisis:
  • Mid-2010s: Over 25% of the world’s population lived in water-scarce regions.
  • Projected to rise to over 40% by 2050.
  • Climate change effects on water security:
    • More extreme precipitation in some areas, drier conditions in others.
    • Changes in frequency and severity of floods, droughts, hurricanes, and wildfires.
    • Accelerated melting of glaciers and permafrost, leading to rising sea levels and freshwater contamination.

• Other Factors Affecting Water Supply:
  • Population growth
  • Rising living standards
  • Increased demand from farming and industry
  • Pollution from agriculture, industry, and transport

Part 2: Factors of Freshwater Availability & Access

Social Factors

• Population growth increases demand for water.
• As income levels rise, water consumption also increases.
• Education influences water use (e.g., awareness of WASH services increases demand for clean water).

Economic Factors

• Water use varies between rich and poor countries:
  • Wealthier people use more water for recreation, gardening, washing cars, etc.
• Agriculture consumes most of the world’s water, reducing availability in farming regions.
• Cost affects access:
  • Piped water is cheaper than buying from vendors.

Cultural Factors

• Climate change is a major cultural factor affecting water access:
  • Greenhouse gas emissions increase global temperatures, leading to droughts and reduced water availability.
• Gender inequality impacts access to freshwater:
  • Women and girls without safe WASH services face higher risks of illness, abuse, and attack, affecting education, work, and quality of life.

Political Factors

• Shared water resources between countries can cause disputes (e.g., Middle East, Grand Ethiopian Renaissance Dam).
• Global water insecurity (2020 data):
  • 2 billion people lacked safely managed drinking water (over 25% of the world’s population).
  • 80% of those without drinking water live in rural areas, many in low-income countries (LICs).
  • Women and girls are disproportionately affected by poor water and sanitation.
  • Marginalised groups (e.g., Rohingyas in Myanmar) have less access to water than Indigenous residents.
• Examples of water cost disparities:
  • Port-au-Prince, Haiti:
    • Households with piped water paid ~US$1.00 per m³.
    • Unconnected households paid between US$5.50 – US$16.50 per m³.
  • Lima, Peru:
    • Poor families on the outskirts paid 20 times more than those connected to mains.
  • Jakarta, Indonesia:
    • Some residents paid 50 times more than those connected to mains.
• Water overuse in farming:
  • Some U.S. farmers overuse water because they don’t pay for it.
  • Over-extraction has depleted aquifers, e.g., Ogallala Aquifer (USA), Sahara and Arabian Desert aquifers.
  • Overuse benefits short-term economic gains but reduces long-term water availability.
  • Negative impacts vary based on income and location.

Part 3: How We Use Water

General Use of Water

• Human societies experiencing population growth or economic development must:
  • Increase water supply
  • Improve efficiency of water use
• Freshwater resources are scarce, and demand is increasing.
• Over 2 billion people lack access to clean drinking water at home.
• 2.3 billion people lack adequate sanitation.

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Unsustainable Demands

• Water demand has continuously grown since the Industrial Revolution.
• Demand is increasing in HICs (high-income countries), MICs (middle-income countries), and LICs (low-income countries).
• Reasons for increased demand in MICs:
  • Population growth
  • Rising standards of living
  • Changing agricultural practices
  • Expanding industries
• HICs consume more water due to:
  • Frequent washing (clothes, cars, personal hygiene)
  • Gardening and recreation
• Increased per capita water use raises demand on finite resources.
• Some countries are reaching their water availability limits.
• Better management and new water sources are required.

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Future Water Scarcity Trends

• By 2025:
  • Global freshwater availability may drop to 5,100 m³ per person (25% decrease from 2000 levels).
• Rapid urbanisation is making it harder to provide clean water and sanitation in shanty towns.
• Water scarcity is increasing in many regions:
  • Sub-Saharan Africa → 300 million people already live in water-scarce areas.
  • Central & Southern Europe → Expected to become drier due to climate change.

Water Consumption by Region

• HICs continue to increase or maintain high water use.
• More water is being consumed indirectly through agricultural and manufactured products.
• Per capita water use:
  • North America & Western Europe: ~3 m³ per day
  • Asia: ~1.4 m³ per day
  • Africa: ~1.1 m³ per day

Key Factors Driving Increased Water Demand

• Population growth
• Rising middle-income populations
• Dietary changes
• Urbanisation
• Climate change
• Growth in tourism & recreation

Based on the above projection,

• Uneven Distribution of Freshwater:
  • The global freshwater supply is not evenly distributed.
  • Seasonal and yearly variations affect water availability.
• Disparity in Rainfall Distribution:
  • Three-quarters of annual rainfall occurs in areas with less than one-third of the world’s population.
  • Two-thirds of the world’s population live in regions receiving only a quarter of annual rainfall.
• Examples of Water Imbalance:
  • Amazon Basin: Holds 20% of global annual run-off, but has fewer than 10 million people.
  • Congo Basin: Accounts for 30% of Africa’s run-off, but is home to less than 10% of Africa’s population.
• Future Water Stress & Climate Change:
  • Rising temperatures increase evaporation and water loss.
  • Freshwater availability is expected to decline in many regions.
  • Potential conflicts may arise between water-rich and water-scarce areas.

Part 4: Development of Water Supply

• Water supplies can be increased through:
  • Dams and reservoirs
  • Rainwater catchment systems
  • Desalination plants
  • Enhancement of natural wetlands

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Dams and Reservoirs

Advantages:

• Flood and drought control
• Irrigation support
• Hydroelectric power generation
• Improved navigation for trade
• Recreational and tourism benefits

Disadvantages:

• Water loss through evaporation
• Salinization of water sources
• Population displacement due to dam construction
• Drowning of settlements in reservoir areas
• Increased earthquake activity (due to reservoir-induced seismicity)
• Channel erosion below the dam
• Silting upstream as sediment accumulates
• Reduced fertility downstream (silt gets trapped behind the dam)
• Higher risk of waterborne diseases (e.g., malaria, schistosomiasis)

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Rainwater Catchment System

• What is it?
  • Collection and storage of rainwater in tanks, wells, boreholes, or to recharge groundwater.
• Uses
  • Drinking, cooking, washing, irrigation, cooling (households, schools, hospitals, industries).
• Advantages:
  • Supplements main water supply.
  • Useful in areas with seasonal water supply.
  • Reduces pressure on mains supply and lowers water costs.
  • Helps reduce soil erosion.
  • Example: Frankfurt Airport collects rainwater for flushing toilets, cleaning air conditioning units, and watering plants.
• Disadvantages:
  • Quality concerns: rainwater from roofs may contain dust, pesticides, and pollutants (e.g., animal faeces).
  • Some systems, like large dams, are costly and may have ecological impacts.
  • Filtering improves quality but can be expensive.
  • Stored rainwater can become contaminated, saline, or brackish over time.
• Usage in Different Regions:
  • 40% of rural households in Thailand rely on rainwater catchment.
  • Compulsory in parts of India (e.g., Tamil Nadu, Rajasthan).
  • Encouraged in new buildings in Indian cities like Mumbai and Bengaluru.

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Desalination and Reverse Osmosis

• What is it?
  • Removal of salt and minerals from seawater/salt marshes to produce potable water and irrigation water.
• Reverse Osmosis:
  • Uses a semi-permeable membrane to separate salt from water.
  • Requires high energy to force saltwater through tiny membrane pores.
  • Expensive due to high energy input.
• Cost of Desalination:
  • New technology is reducing costs.
  • Example: Sorek plant in Israel produces desalinated water at US$ 0.60 per m³.
  • Cost comparisons:
    • Japan: US$ 1.21 per m³.
    • USA: US$ 0.5–1.0 per m³.
• Environmental Concern:
  • Disposal of removed salt (brine) can negatively impact local ecosystems if added to water bodies.

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Enhancement of natural wetlands

• Rainwater can be harvested from lakes, rivers, and natural wetlands.
• Water availability and quality vary by location.
• Wetland enhancement involves improving a wetland’s function, such as:
  • Dredging or deepening to increase water storage
  • Restoring indigenous species
  • Removing invasive species

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Exercises