Water Resources Chapter 9

Water as a Resource 70% of earth’s surface is covered by water 97-98% is found in the oceans as salt water Less than 3% is freshwater and the majority of the freshwater is found in ice and glaciers and the rest resides underground http://snr-1349.unl.edu/navigation/waterdistribution.aspx

Groundwater Exists 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 Groundwater recharge – where water goes through the soil and works it way into the aquifer

- water naturally rises to the ground surface b. artesian wells 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 * Springs serve as a major source of freshwater for aquatic biomes and a source of drinking water for humans 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very quickly - contamination with chemicals Largest aquifer - Ogalla in the Great Plains - lots of water is being withdrawn (problem!) May recharge with water that fell from the ground last night or last year whereas recharge in confined aquifers is very slow, 10-20,000 years therefore is it much older and less contaminated

Cone of Depression a. an area where there is no longer any ground water b. water table drops too low c. comprises water quality

a. drilling wells along coastline Saltwater intrusion a. drilling wells along coastline b. rapid pumping lowering water table c. adjacent saltwater infiltrates in Rapid pumping reduces the water pressure in the aquifer allowing the saltwater to move in and contaminate the water with salt

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 Rivers – measured by the volume of water they carry

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 Lakes – depressions in the earth’s surface that are filled by precipitation, runoff that is not absorbed from surrounding areas and groundwater Oligotrophic – low productivty due to low amounts of nutrients such as phosphorus Eutrophic – high level of productivity

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 Essential to global water distribution Drought Drys out soil – loss of soil fertility Soil may become harden and impermeable causing water to runoff and eroding the topsoil in the process

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 * Preventing flooding in order to use the floodplain for commercial and residential use

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)

a. canals/ditches used to carry water from one place to another 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 Typically water is removed from a lake or river and transported to wherever it is needed Earlier ones were made up of limestone NYC uses the aqueduct in the Catskills and LA gest their water from the Colorado River Diverting water also means that there is now less water where there used to be more Can result in a lower flow of freshwater into estuaries, meaning more ocean water moves farther up the river, increasing the salinity of the estuary harming aquatic life (example: India and Bangledesh) Diversion project - reduced the amount of freshwater into the aral sea, increasing salinity - reduced the surface area of the sea which in turn affected the local climate

Desalination (desalinization) a. removing salt from sea water b. 2 common techniques 1. distillation 2. reverse osmosis - leaves behind a brine (high salt concentration) water-poor countries way of obtaining fresh water Distillation - heat water to a boil, leaving the salt behind as a precipitate - steam that is produced is captured and condensed, resulting in pure water - requires lots of energy Reverse osmosis - water is forced through a thin semi-permeable membrane at high pressure - water can pass through, but salt cannot - newer and often less costly - brine (returned to open ocean), could harm soil, plant life and animal life http://bcs.whfreeman.com/friedlandapes/#668210__690864__

Water Use Freshwater a. 70% - agriculture 30% - industrial and household Proportion varies from person to person and country to country http://www.data360.org/dsg.aspx?Data_Set_Group_Id=757

b. US: 1/3 of freshwater is used for irrigation 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) together, india, china, us and pakistan account for more than half of the irrigated land in the world Furrow – oldest technique; farmer digs a trench along the crop row and fills them with water to provide moisture for the plant roots Spray – more expensive; water pumped from a well into an apparatus that has nozzles to spray the entire field Drip – reduces weeds by keeping the surface soil dry and discouraging weed germination

c. hydroponic agriculture 1. alternative to traditional agriculture 2 c. hydroponic agriculture 1. alternative to traditional agriculture 2. crops under greenhouse conditions 3. uses 95% less water than traditional irrigation Roots are emersed in nutrient-rich solution, not soil Can grow things anytime of the year since it is a controlled setting http://blog.syracuse.com/cny/2011/01/hydroponic_farming_satisifes_central_new_yorks_craving_for_local_greens_in_midwinter.html

a. in US, ½ water goes towards electricity b. cools machinery (steam) Industry a. in US, ½ water goes towards electricity b. cools machinery (steam) c. refines metals d. used to make paper Electricity Some water is consumed when making electricity, some is not Cooling machinery Plants use heat to convert water to steam

a. in US, 10% water used in homes b. Indoor use 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 Where we live, determines the amount of water that is used daily by the average person Drinking water More than 1 billion people lack access to clean drinking water. 1.8 million people die due to diarhheal diseases because of contaminated drinking water, most are childrean

Water Conservation A NECESSITY! Improved efficiencies in toilets and shower heads Plant vegetation that’s appropriate for your climate a. Las Vegas, Nevada