Environmental Management (0680) | Water supply

🌊 Environmental Management (0680) Study Notes: Water Supply 💧

Welcome to the "Water Supply" chapter! This is one of the most critical sections of Environmental Management because water is essential for life, but it's distributed unevenly and is highly vulnerable to human activities. Don't worry if some concepts seem complex—we'll break them down using clear steps and relatable examples so you can master them!

4.3 & 4.4: Where Does Our Water Come From and How Do We Use It?

Think of the Earth's freshwater supply as a very precious, limited resource. Humans rely on several sources to meet their needs.

Sources of Freshwater Used by People (4.3)

• Aquifers and Wells:
  An aquifer is an underground layer of permeable rock that holds groundwater. We access this water by drilling wells. (Analogy: Think of an aquifer as a massive underground sponge holding water.)
• Rivers and Lakes:
  Surface water sources. These are easily accessible but often heavily polluted or prone to seasonal changes (drought/flood).
• Reservoirs:
  Artificial lakes created by building a dam across a river valley. They store water during wet seasons for use all year round.
• Desalination Plants:
  Processes (like reverse osmosis) that remove salt from seawater, making it drinkable (potable). This is energy-intensive and expensive, usually used in water-scarce coastal regions (e.g., the Middle East).

Ways Freshwater Is Used (Water Usage) (4.4)

Freshwater usage is generally divided into three main categories. Guess which one uses the most globally? (Hint: it’s not washing dishes!)

• Agricultural Use:
  This is the largest consumer globally, mainly for irrigation (watering crops).
• Industrial Use:
  Used for cooling machinery (like in power stations), manufacturing processes, and as a solvent.
• Domestic Use:
  Water used in homes for drinking, cooking, washing, sanitation (toilets), and gardening.

4.5: Water Quality and Availability – The Global Divide

Access to safe, clean drinking water (potable water) is not equal worldwide. This inequality is a major source of environmental and social problems.

The Divide: Water-Rich vs. Water-Poor Regions

• Water-Rich Regions: Areas with high rainfall, large rivers, and stable political structures, making water management and treatment easier (e.g., many parts of Europe or North America).
• Water-Poor Regions: Areas suffering from low rainfall, high evaporation, or areas with poor infrastructure or political instability.
• Potential for Water Conflict: When two or more countries share a crucial water source (like the Nile River or the River Jordan), competition over usage can lead to diplomatic disputes or even war. This is known as transboundary water conflict.

Urban vs. Rural Access

• Urban Areas (Cities): Generally have better access to safe water because infrastructure (pipes, treatment plants) is concentrated and easier to maintain. However, rapid urban growth can overwhelm these systems.
• Rural Areas (Countryside): Access is typically much lower. People often rely on shallow wells or natural streams, which are easily contaminated by sewage or agricultural runoff. Fetching water (often done by women and children) takes time away from education or work.

4.6: Major Water Management – Multipurpose Dam Projects

Dams are huge structures built across a river to create a reservoir. When designed to serve multiple functions (not just generating electricity), they are called multipurpose dam projects.

Choice of Site for a Dam

Building a dam is a massive investment and requires careful planning. An ideal site needs:

• A narrow valley or gorge (minimises the size and cost of the dam wall).
• A large upstream catchment area (to ensure enough water fills the reservoir).
• Stable geology (the underlying rocks must be strong enough to support the massive weight of the dam and the water).
• Minimal human settlement nearby (reduces the number of people who need to be relocated).

Evaluating Impacts and Sustainability

Dams have significant trade-offs, impacting the environment, the economy, and society.

Environmental Impacts

• Negative: Flooding of large areas (loss of habitat and biodiversity), changes to the river’s natural flow downstream (affecting wetlands), increased sedimentation behind the dam, and changes in water temperature/chemistry.
• Positive: Flood control downstream, steady water supply maintaining minimum river flows in dry periods.

Economic and Social Impacts

• Negative: Expensive to build and maintain, displacement of thousands of people (social trauma), loss of valuable farmland to the reservoir, potential for the dam to fail catastrophically.
• Positive: Generates hydro-electric power (HEP) (clean energy), provides water for irrigation (boosting agriculture), tourism opportunities, and recreational use (boating).

Sustainability: For a dam project to be sustainable, its benefits must outweigh the costs over the long term, and environmental damage must be mitigated (e.g., compensating displaced people, protecting downstream ecosystems).

4.7 & 4.8: Water Pollution and Its Impacts

Water pollution happens when harmful substances contaminate water bodies. This severely affects both people and the environment.

Sources of Water Pollution (4.7)

• Domestic Waste/Sewage:
  Untreated human waste and wastewater from urban and rural areas. This introduces bacteria, pathogens, and high levels of nutrients (like nitrates and phosphates).
• Industrial Processes:
  Discharge of heat (thermal pollution), heavy metals (e.g., mercury, lead), and various toxic chemical substances into rivers and lakes.
• Agricultural Practices:
  Runoff containing fertilisers (nutrients), pesticides, herbicides, and animal manure (faeces and pathogens).

Impacts of Water Pollution on People and Environment (4.8)

Impacts on People (Health)

• Infectious Bacterial Diseases: Poor sewage treatment leads to the spread of diseases like typhoid and cholera. These cause severe diarrhoea and dehydration, often deadly, particularly in areas with poor sanitation (Global inequalities in sewage and water treatment are a major factor).
• Toxic Substances: Consumption of fish or water contaminated with industrial heavy metals can cause long-term health problems and organ damage.

Impacts on the Environment

• Eutrophication: This is a critical process you must understand step-by-step!
  1. Excess nutrients (from fertilisers/sewage) enter the water (nutrient enrichment).
  2. This causes a rapid increase in algae growth (an algal bloom).
  3. The thick layer of algae blocks sunlight, killing plants underneath.
  4. The algae then die and are broken down by decomposers (bacteria).
  5. The bacteria use up huge amounts of dissolved oxygen in the water.
  6. The lack of oxygen kills fish and other aquatic organisms.
  (Analogy: Eutrophication is like accidentally overfeeding your pet fish so badly that the leftover food decays, uses up all the oxygen, and suffocates them.)
• Bioaccumulation and Biomagnification:
  Toxic substances (like mercury or DDT) released by industrial processes are taken up by tiny aquatic organisms. They build up (bioaccumulation) in tissues. As these organisms are eaten by larger predators, the toxins become much more concentrated higher up the food chain (biomagnification), harming top predators (like large fish, birds, or humans).
• Acid Rain:
  Pollution (sulfur dioxide and nitrogen oxides) causes acid rain, which lowers the pH of lakes and rivers, making them toxic for fish and other aquatic organisms.

4.9 & 4.10: Managing Water Quality and Disease

Strategies for Improving Water Quality (4.9)

The goal is to stop pollutants from entering the water, and to clean the water that is already contaminated.

• Improved Sanitation:
  Providing access to toilets and basic hygiene facilities, especially in rural areas, reduces the entry of human waste into water sources.
• Treatment of Sewage:
  Building and maintaining effective sewage treatment plants (which remove solids, treat water with microbes, and disinfect it before discharge). This is a vital step in controlling infectious diseases.
• Pollution Control and Legislation:
  Passing and enforcing laws that limit the amount of toxic effluent (waste) industries can discharge into water bodies. Fines can deter illegal dumping.
• Managing Agricultural Runoff:
  Reducing the use of chemical fertilisers or timing their application to avoid heavy rainfall periods.

Managing Water-Related Diseases (4.10)

Controlling Cholera and Typhoid

These are typically spread through contaminated water (ingested). The key strategy is prevention:

• Safe Drinking Water Supply (Potable Water): Ensuring clean water is accessible to everyone.
• Boiling: Heating water to kill all bacterial pathogens.
• Chlorination: Adding small amounts of chlorine (or bleach) to disinfect the water. This is cheap and effective for emergencies.

Controlling Malaria

Malaria is caused by a parasite, carried by a vector (the Anopheles mosquito), and is often associated with still or stagnant water bodies (where mosquitoes breed).

• Vector Control: Reducing mosquito numbers using mosquito nets, insecticides, or draining areas of stagnant water (removing breeding sites).
• Antimalarial Drugs: Medication taken to prevent or treat the infection in humans.
• Eradication: Large-scale attempts to eliminate the parasite or vector entirely from a region (though often difficult to achieve).