12.3. Water Pollution Flashcards
Drought
a period of below-average precipitation in a given
region, resulting in prolonged shortages in the water supply, whether atmospheric, surface water or ground water
Importance of Water
- Human body is 60% water
- Need water to compensate for fluid loss throughout the day
- Fresh-water is such a vital commodity to human civilisation. So increasingly, it is even becoming a source of conflict
- Why? Rivers flow across multiple countries, and when a country dams a river, then water supply would be cut off for the other countries
Supply of Water
- The point is that the supply of fresh water is a finite, whilst demand huge and increasing.
- 3% of the world’s water is fresh water and 97% is saline ocean water
- Out of this, 69% is Icecaps and Glaciers, 30% is groundwater, and 0.3% surface water
- Out of the surface water, 87% is found in lakes, 11% swamps, 2% rivers
Demand
This is the need for water for a range of uses, also referred to as consumption. (The amount of water consumed reflects the level of demand)
Supply
The availability of water by tapping various sources, such as groundwater and surface water (lakes and rivers).
Water Balance (+ or -) =
Water Supply – Water Demand
Demand for Water
1) Agriculture:
In many parts of the world, precipitation is low and therefore farmers need to irrigate their crops.
2) Industrial Use:
Industry uses huge amounts of water for manufacturing or for cooling (e.g. power stations).
3) Domestic use:
In HICs, large amounts for a huge range of every day uses as well as sanitation and drinking; In LICs, less is used, mostly for drinking.
What’s the dominant demand for water?
Agriculture (Very High), then domestic, then industry
Factors driving increased demand
- Driving reason for increase rising population.
- Rising standard of living = high domestic use.
- Rise in agricultural productivity to feed people = higher use.
- Industrialisation hand in hand with development. Industry needs water.
Evidence for increased demand for water
Between 1950 and 2000:
- Demand from agriculture from c. 1000 cubic KM/year to 3000 (x3)
- Demand from Industry and Domestic from c. 250 to 2,000 (x8)
Water Deficit
Demand > Supply
Water Surplus
Supply > Demand
Water Deficits and Surpluses within a country
different regions within a country can have different climates and levels of population density, thereby creating internal areas of surplus and deficit.
We can further split those areas that are suffering from water deficit down into:
Physical water scarcity and Economic water scarcity
Physical Water Scarcity
Occurs where water consumption exceeds 60% of the usable supply of water.
Economic Water Scarcity
Occurs where a country physically has enough water resources to meet its needs, but a shortage of treatment, storage or transport facilities means that supply cannot meet demand.
Reasons for water deficit
- Climate: Precipitation and temperature (evaporation);
- Physical landscape (proximity to rivers and geology);
- Population density, growth and distribution;
- Economic Development (demand and supply infrastructure)
- The importance / prevalence of agriculture.
Quality Vs Quantity
- Quality is more important
- It is a trite distinction to make, but it reinforces the point that water for domestic uses, especially drinking water, needs to be clean and free of diseases.
- Natural water is rarely clean enough to drink, therefore
treatment works and infrastructure to deliver clean water to people is required.
Providing Clean Water
- It is generally considered to be a government’s role
to provide this infrastructure. - The infrastructure is relatively affordable.
- However, it can be difficult to provide, maintain or this
infrastructure in rural environments or remote areas, especially in LIC and MIC countries.
Factors that impact water quality
Water, like air, is fluid and therefore polluted or poor quality water can easily spread over long distances
1) Agriculture
2) Industry
3) Energy production:
4) Domestic waste
Factors that impact water quality (Agriculture)
- Through increasing use of chemical fertilisers as well as animal waste. Leaching and surface run-off washed into water courses or groundwater, degrading water quality or causing eutrophication.
- Pesticides, Herbicides
Factors that impact water quality (Industry)
- Liquid wastes or by-products are often dumped into water courses rather than expensive processing, especially in LICs
Factors that impact water quality (Energy production)
- Oil spills, air pollution leading to acid rain, hot water from thermal power stations being dumped, containing little oxygen, low-level radioactive waste from nuclear power.
Factors that impact water quality (Domestic waste)
- If there is inadequate sanitation infrastructure, sewage or domestic waste water can easily pollute watercourses or groundwater in LICs;
- Domestic rubbish is often dumped in HICs, or poor waste collection services in LICs / MICs lead to a higher chance of waste being washed into water courses.
Niger Community Wells - Needs
- Lowest HDI with large rural population and very large country.
- Reliance on groundwater, but arid region and no sanitation so groundwater easily contaminated.
- Existing wells widely scattered; time and labour consuming
Physical water scarcity
- Arid country, with the Sahara desert, so it has low levels of water to use
Economic water scarcity
- The country is so remote that the government can’t implement (lack of money too) fresh water infrastructure
- Reliance on groundwater - domestic pollution through sanitation and Agricultural waste - animal waste
Niger Community Wells - Advantages
- Reliable, local source of freshwater with health benefits.
- Frees time for education and economic activity.
- Drilling and pump manufacture provides employment.
Niger Community Wells - Disadvantages
- Potentially cost and over-extraction of groundwater.
Philippines Water Shops - Needs
- Rapidly growing population and urbanisation in an LIC, with attendant issues of providing modern infrastructure.
- Public distrust of previously contaminated water supply.
- This overcomes the supply of issue where demand is rapidly growing and it is difficult to provide infrastructure
- Overcomes the issue of domestic and industrial water quality in urban areas
Philippines Water Shops - Advantages
- Fraction of the cost of commercially bottled water.
- Reliable supply, often in conjunction with the government.
- As the shops are often private, they are not solely funded by govt.
Philippines Water Shops - Disadvantages
- Groundwater over-extraction and contamination from unauthorised sellers;
- Does not address the long-term water supply and quality issues.
