Geo lecture #17

Types of usage 

• consumptive= drinking and irrigation 

• nonconsumptive= does not diminish the supply of water available for subsequent usage (transport of goods, recreation, sanitation, hydroelectric power, etc) 

• Can change the composition or temp of the water

Categories of water usage

• Public supply, domestic, irrigation, thermoelectric, industrial, mining, livestock, aquaculture

Water usage

• Cali accounted for 9% of total water use in the U.S in 2015

Freshwater usage 

• Daily drinking water requirement=2-4L per person 

• Daily food production=2,000-5,000L per person 

• Freshwater use has been increasing about 1% per year since the 1980s

• Peak water- concept that underlies growing constraints on the availability, quality and use of freshwater resources

-there is a vast amount of water on the planet but sustainably managed water is becoming scarce

-nearly 4 billion people experience severe water scarcity at least one month of each year

Water quality 

• Drinkable water has <500 ppm dissolved solids 

• Rainwater has 1-2 ppm of solid matter that dissolves from the atmosphere and a ph <6 due to the absorption of co2 

Acid rain

• Coal contains significant sulfur-so2 released during coal combustion produces sulfuric acid (H2so4)

• Burning petroleum emits no2 which produces nitric acid

U.S clean air act

• Sig reductions in so2 and no2 due to 1970 u.s clean air act

No emissions in so cal

• South coast air quality management district (aqmd) still has significant np emissions-ley pollutant that creates ozone-need to reduce by 67%

Recall: aquifers in cali

• During an average year, 515 groundwater basins 

• Contributes about 38% of the state's total water supply, but this increases to about 46% in drought years.

Desalination 

• Removing salt from water by distillation or membrane filtration 

-distillation is boiling seawater and condensing steam

-reverse osmosis membrane=pressure pushes saltwater through a water-permeable membrane that separates water molecules from larger ions 

California desalination plants 

• 12 desalination plants in ca-carlsbad is the largest in the western hemisphere 

• Orange county dana point facility approved last fall 

Drinking water contaminants 

• US enviromental protection agency (EPA) sets legal limits=macimum contaminant level (MCL) on over 90 contaminants in drinking water

• Point source (pipe emptying into a river)

• Nonpoint ( fertilizer runoff from farmland)

Drinking water contaminants 

• USGS 2008 study found 130 man-made chemicals in natural waters in the US but most are unregulated in drinking water and no required to be removed or monitored