Chapter 9

Water as a Resource

http://snr-1349.unl.edu/navigation/waterdistribution.aspx

GroundwaterExists in aquifers (permeable layers of rock and

sediment) a. confined aquifer b. unconfined aquifer

• Water table a. uppermost level where water still saturates

rock or soil b. “surface of the groundwater”

• Groundwater recharge

Sources of aquifers a. springs - source of freshwater - water naturally rises to the ground

surface

b. artesian wells - drilling in confined aquifer - releases pressure on the water

http://www.ec.gc.ca/eau-water/default.asp?lang=En&n=300688DC-1

Problems with water from unconfined aquifer - recharge very quickly - contamination with chemicals

• Largest aquifer - Ogalla in the Great Plains - lots of water is being withdrawn (problem!)

Cone of Depression a. an area where there is no longer any

ground water b. water table drops too low c. comprises water quality

Saltwater intrusion a. drilling wells along coastline b. rapid pumping lowering water table c. adjacent saltwater infiltrates in

Surface WaterFreshwater that exists above ground - streams, rivers, ponds, lakes, and wetlands

• Rivers a. 3 largest - Amazon in SA - Congo in Africa - Yangtze in China

b. land surrounding rivers is typically fertile c. floodwaters deposit nutrient-rich sediment onto the floodplain

•Lakes a. classified by level of primary productivity b. oligotrophic v. eutrophic

•Wetlands a. control flooding

Atmospheric WaterDrought a. long-term effects on soil

• Flooding a. water input exceeds the ability of an area to

absorb the water b. areas affected by drought-impermeable

surfaces- flood

Altering the Availability of Water

Levees a. enlarged bank built up on each side of the river

b. Mississippi River – largest system of levees c. major challenges

- floodwater no longer add fertility to floodplain

- sediments will deposit further down where river

meets ocean - cause even worse flooding downstream

- can collapse

Dikes a. built to prevent ocean waters from

flooding adjacent land b. common in Europe – farmland below sea

level

Dams a. barrier that runs across the river or stream to

control the flow of water b. reservoir c. used to generate electricity d. world’s largest – Three Gorges Dam in China e. environmental problems - interruption of natural flow of water (fish

ladders)

Aqueducts a. canals/ditches used to carry water from one place to another b. concrete canals and pressurized steel pipes c. In the US: NYC and LA d. ensures clean water, but disturbs habitats e. diversion project - Soviet Union diverted two rivers that fed into the

Aral Sea

Desalination (desalinization) a. removing salt from sea water b. 2 common techniques 1. distillation 2. reverse osmosis - leaves behind a brine (high salt concentration)

http://bcs.whfreeman.com/friedlandapes/#668210__690864__

Water UseFreshwater a. 70% - agriculture 30% - industrial and household

http://www.data360.org/dsg.aspx?Data_Set_Group_Id=757

Agriculture a. largest use of water b. US: 1/3 of freshwater is used for irrigation 1. furrow – 65% efficient 2. flood – 70-80% efficient 3. spray – 75-95% efficient 4. drip – over 95% efficient (reduces weed

growth)

c. hydroponic agriculture 1. alternative to traditional agriculture 2. crops under greenhouse conditions 3. uses 95% less water than traditional irrigation

http://blog.syracuse.com/cny/2011/01/hydroponic_farming_satisifes_central_new_yorks_craving_for_local_greens_in_midwinter.html

Industry a. in US, ½ water goes towards electricity b. cools machinery (steam) c. refines metals d. used to make paper

Household a. in US, 10% water used in homes b. Indoor use 1. flushing toilets (41%), bathing (33%),

laundry (21%), and cooking/drinking (5%) c. Outdoor use 1. watering lawns, washing cars, etc. d. drinking water

Water ConservationA NECESSITY!

Improved efficiencies in toilets and shower heads

Plant vegetation that’s appropriate for your climate

a. Las Vegas, Nevada