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Bdale Envir Ch 14 – Water Resources and Water Pollution - page 3 / 7





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- Worldwide, dams increase amt of runoff available for human use by 1/3

But there are problems with dams too…reduced downstream flow, and disruption of ecology that is dependent upon periodic flooding that is stopped by dams

Dams also provide electric power, cleaner than with coal power plants

- large scale water transfer

Miller cites California water project as example –

An example of a disaster was the Aral Sea transfer, where the size of the sea has decreased dramatically in 40 years (story on p.335)

- groundwater withdrawal

there are a number of problems with increasing GW withdrawal

scary stat – in US, GW is being withdrawn at 4 times the replacement rate !


desalination is used but does not contribute much volume at this point in time, and it is both expensive and environmentally harmful (due to all the salt waste)

14-4 too much water

Miller discusses problems with flooding

Flooding is very important to agriculture, because nutrient-rich silt gets deposited on the floodplain during flooding, and this creates good crop conditions

Because floodplains are so important for agriculture many people in developing countries insist upon settling there, and then they are subject to danger during flooding

14-5 types, effects, sources of water pollutants

Table 14-1 lists major categories:

Infectious agents (bacteria, etc)

Organic waste (takes free oxygen away from fish)

Inorganic chemicals (acids, heavy metals)

Organic chemicals (oil, gasoline, pesticides, solvents)

Plant nutrients (nitrate, phosphate, ammonium)

Sediment (soil, silt)

Radioactive materials (uranium, radon, etc)

Heat (power plant cooling, etc)

Measuring water quality

Several methods:

Coliform bacteria count – the lower the better

BOD (biological oxygen demand) – essentially the amount of dissolved oxygen (DO) in the water required by aerobic decomposers to break down waste matter – the more DO, the less waste matter is in the water

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