Edexcel IGCSE Geography 复习笔记 1.3.2 Water Quality & Supply

• 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

• 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

转载自savemyexams