Chapter 9

Water as a Resource

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



Groundwater

Exists in

aquifers

sediment) (permeable layers of rock and 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very quickly - contamination with chemicals • Largest aquifer - Ogalla in the Great Plains - lots of water is being withdrawn (problem!)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 Water

 Freshwater 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 Water

 Drought 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 Use

Freshwater 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.ht

ml

 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 Conservation

 A NECESSITY!

 Improved efficiencies in toilets and shower heads  Plant vegetation that’s appropriate for your climate a. Las Vegas, Nevada