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Edexcel IGCSE Geography 复习笔记 1.3.2 Water Quality & Supply

Category: IGCSE课程, 国际课程, 教材笔记, 福利干货 Date: 2022年7月22日下午4:01

Edexcel IGCSE Geography 复习笔记 1.3.2 Water Quality & Supply

Variations in Water Quality

Clean, potable water is essential for human consumption, irrigation and for livestock
Approximately one-third of the world's population does not have access to clean, potable water
Unsafe water results in an estimated 1.2 million deaths worldwide each year
In areas with low precipitation water can become stagnant
Diseases which spread in polluted water include typhoid, cholera, bilharzia and dysentery
There are many sources of water pollution and it is estimated that globally 80% of wastewater enters the water system without being treated

Sources and Impacts of Water Pollution

Source	How it Enters the Water	Impact
Agriculture	Waste water from silage and slurry Fertilisers, herbicides and pesticides Soil erosion	Death of fish and other river wildlife, introduces bacteria into the water Can cause eutrophication and be poisonous to fish and other wildlife Increases the sediment entering the river increasing turbidity which decreases oxygen levels
Industry	Spillages of oil Water being used as a coolant and returned to rivers at higher temperatures Toxic substances from industrial processes	Oil stays on the surface of the water, wildlife and plants become coated in oil and cannot eat/move/fly Animals and plants within the water system cannot survive in higher temperatures Toxins enter the food chain and are harmful to wildlife and humans
Domestic	Untreated sewage Water used for washing clothes and bathing Water used for leisure which has been treated with chlorine	Increases the levels of nitrogen in the water and introduces bacteria Chemicals used in washing powder/liquid, bleach, shower gels, and soap all can be harmful to wildlife Chlorine is bleach which affects wildlife causing chemical burn

Exam Tip

Remember to be clear about the difference between causes and impacts. The cause of pollution is where it comes from and how it enters the water. The impacts are how the environment, humans and wildlife are affected by the pollution.

Storage & Supply of Clean Water

1 in 3 people do not have access to clean drinking water
In developed countries over 90% of people have access to clean water due to better water supply and storage infrastructure
In some developing countries, poor water supply and storage infrastructure means over 60% of people don't have access to clean water
Water infrastructure ensures that people receive clean, potable water
Water is collected from rivers, lakes, reservoirs and aquifers - the amount taken from each depends on location
In arid areas people rely more on groundwater
Where there is effective infrastructure, water is collected, treated and delivered

Collection

Dams and reservoirs are used to collect and store water
Wells and boreholes allow access to groundwater

Treatment

All water, even groundwater is likely to have some contaminants
Developed countries and urban areas in developing and emerging countries have treatment works:
- Water goes through a series of processes including filtration and disinfection
- The treatment process removes solid waste, bacteria, viruses, fungi, minerals and chemical pollutants
In rural areas and some urban areas in developing and emerging countries water may be treated where it is going to be used due to a lack of treatment works

Delivery

Water is often delivered by pipeline directly from the treatment works to homes and factories
Pipelines and infrastructure are expensive and need to be maintained
Developing and emerging countries, particularly in rural areas, are less likely to have this infrastructure
In urban areas in developing and emerging countries, standpipes may be used which are shared by many people
In rural areas in developing and emerging countries, wells are the main water source but this is usually untreated

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