Chapter 9 Water Resources

Transcription

1 Chapter 9 Water Resources

2 16,000 mi 2 of watershed

3 3 rd largest Salmon fishery. Salmon lay eggs upstream, eggs hatch, fish swim down stream, mature, swim back upstream to the place of their birth to lay their eggs. Dams prevent this upstream movement. Dammed for electricity, farmers have settled and diverted water for irrigation (last 100 years). 4 hydroelectric dams between Huge benefit because there is less pollution. Early 1900 s US Bureau of Reclamation installed canals to drain the two large lakes that were the source of the river. Dams caused water temps to rise. Positive feedback loop created

4 1997 Coho Salmon given protection under the US Endangered Species Act. Meant withdrawals could not reduce the river s flow below a minimum level. Created a debate over the various interest groups: Native Americans Hydroelectric companies Farmers Commercial fishing industry

5 Water is Abundant But Usable Water is Rare

6 Groundwater Aquifers- small spaces found within permeable layers of rock and sediment where water is found. Unconfined aquifers- an aquifer that is simply porous rock covered by soil. Confined aquifers- an aquifer surrounded by a layer of impermeable rock or clay.

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8 Groundwater Water table- the uppermost level at which the water in an area fully saturates the rock or soil. Recharge- the input process of water percolating into an aquifer. Springs- water from an aquifer that naturally percolates up to the surface. Spring water can be used directly by humans as a source of drinking water.

9 Groundwater Cone of depression- an area where there is no longer any groundwater.

10 Groundwater Saltwater intrusion- when the pumping of fresh water out of a well is faster than the recharge. Near coastal areas this can cause salt water to infiltrate the aquifer.

11 Surface Water Streams, rivers, ponds, lakes and wetlands. Early civilizations settled near rivers as a source of transportation and because the land surrounding the rivers (floodplain) were extremely fertile from rivers naturally overflowing their banks. Determining the Largest lakes is difficult because it depends on your point of measurement: Surface area, volume or depth.

12 Surface Water Productivity (amount of nutrients) in a lake: Oligotrophic- low amounts of nutrients such as phosphorous and nitrogen. These types are good for recreation: swimming, boating, etc. Mesotrophic- a moderate level of productivity Eutrophic- high levels of productivity

13 Called blue water (liquid called green water) Essential to global water distribution. Droughts have long-lived effects on soil. Top soils blow away. Soils become severely parched and harden to become impermeable. Droughts affect nutrient cycling. And thus soil fertility The dust bowl: the Southern Great Plains April 14, 1935 Huge dust storm that traveled as far as Washington DC. Sun entirely blocked out in the Southern Great Plains

14 Washington DC

15 Don t usually experience high amounts of precipitation, but when they do, severe flooding can occur. Soil baked hard, making it impermeable Same effect as paved roads and impermeable surfaces of the like in big cities. Like droughts, floods can cause crop and property damage as well as loss of human and animal lives.

16 Altering the Availability of Water Levees- an enlarged bank built up on each side of the river. Mississippi river has the largest system of levees in the world. Flood waters no longer add fertility to floodplain. Sediments are carried down stream and settle in the ocean. Force flood water further down stream causing worse flooding. Encourages development in floodplains. Hurricane Katrina, New Orleans, Dikes- similar to a levee but built to prevent ocean waters from flooding adjacent land.

17 2008 levee break in St. Louis, Missouri

18 Altering the Availability of Water Dams- a barrier that runs across a river or stream to control the flow of water. Water stored behind the dam in a reservoir. 3% of dams used to help in hydroelectric operations. World s Largest= Three Gorges. Use large amounts of energy, materials and displace a lot of people. Interruption of natural flow of water to which organisms are adapted. Fish ladders: built like stairs to alleviate this problem.

19 Altering the Availability of Water Aqueducts- canals or ditches used to carry water from one location to another. Lose 55% of the water they carry through evaporation or leakage. Some of the largest US cities depend on aqueducts for their daily water supplies (New York and Los Angeles). Many international conflicts occur: Bangladesh down river from India. India wants to divert water from over 50 rivers s Soviet Union diverted water from two rivers that fed the Aral Sea.

20 Altering the Availability of Water Desalination- removing the salt from salt water to obtain fresh water. Facts: Middle Eastern and North African Countries make up 5% of the worlds population but have only 1% of the world s water. Middle Eastern countries account for half of the world s desalinated water. Distillation Reverse osmosis Equipment is less costly and more efficient. Preferred method.

21 A human can survive 3 weeks (plus) without food, but only a few days without water. World fresh water use: 70% agriculture 30% split between industry (~20%) and household (~10%). Throughout the past 50 years, water for agriculture has more than doubled. U.S. ~ 1/3 of all fresh water usage. U.S., India, China account for 50% of irrigated land

22 Agriculture, Industry and Household Needs Agriculture- the largest user of water around the world. (Approx. 70%) Facts: Over the past 50 years, water use for irrigation has doubled because of increased population. More than half the irrigated land in the world is located in China, US, India and Pakistan.

23 Agriculture, Industry and Household Needs Irrigation techniques- Furrow irrigation- a trench that is flooded with water. (easy, inexpensive, 65% efficient) Flood irrigation- the entire field is flooded with water. (more disruptive, 70-80% efficient) Spray irrigation- an apparatus that sprays water across a field. (more expensive, fair amount of energy usage, 75-95% efficient) Drip irrigation- using a slow dripping hose that is laid on or buried beneath the soil. (over 95% efficient, reduced weed growth, great for perennial plants) Hydroponic agriculture- crops grown in fertilized water and no soil. (water can be reused, more crops per hectare, every season, little/no pesticides, costs a bit higher)

24 Agriculture, Industry and Household Needs Industry- the second largest user of water worldwide. (Approx. 20%) Generating electricity, cooling machinery, refining metals and paper

25 Agriculture, Industry and Household Needs Households- the third largest user of water worldwide. (Approx. 10%) 157 gallons per day (U.S.) U.S. indoor water use similar across the states, outdoor varies tremendously. 10% of all water used

26 Toilets manufactured before 1994 typically required 27 L (approx. 7 gals) per flush. Federal Standards altered this to 6 L (approx. 1.5 gal) per flush in January 1994.

27 Earth s water is not distributed evenly. 1.2 billion people (15%) lack access to clean drinking water. 1.8 million people die from diarrheal diseases related to contaminated water. The future of water availability will depend on many things: How we resolve issues of ownership. How we improve water conservation. Development of water-saving technologies.

28 The Future of Water Availability Water ownership- people can have rights to water use, but they do not own the water. Experts believe that as populations continue to grow, so will conflict over water. Water conservation- using techniques such as more efficient water fixtures, faucets and washing machines. Using plants that are adapted to the environment will reduce the need for irrigation. (Xeriscaping)

29 Potable water: Clean drinkable water. Gray water: Used water coming from uses such as showering, washing clothes/dishes, brushing teeth, etc. May be recycled to do things such as flush toilets, wash cars, water plants. Black water: Used water from toilets. Fact: Gray water use in Sydney, Australia saves up to 50,000 L per household annually. Approx 13,200 gal