Water Chapter 5 Part I

I. Our Water Resources A. Water is a necessary resource. 1. People can only survive a few days without water. 2. People live longer now because of having clean water. 3. Water use in the United States: a. 47 % agricultural b. 44% industry c. 9% residential

B. Water, Water Everywhere, but… 1. About 70% of the Earth’s surface is covered with water. 2. About 97% is salt water that we cannot drink. 3. Only 3% is freshwater. a. 76% is frozen in polar ice caps b. only a tiny bit if the earth’s water is available for use = surface waters & ground water.

C. Surface water = freshwater that is above ground in lakes, ponds, rivers, and streams 1. All rivers are the result of precipitation a. as rain falls and snow melts, water drains from mountains, hills, plateaus, and plains. b. the entire area that is drained by a river is a watershed. example: the Muskingum County Watershed drains into what river?

2. Rivers of Controversy a. many people rely on water that comes from another sate or country, so conflicts over water are common. b. questions include: i. how much water do countries upstream and downstream get? ii. Who gets to decide and regulate the use? c. building dams on the river causes more problems on the river because they reduce water flow d. water rights problems will get worse in the future.

3. Dams = structures built across a river or stream that prevents most of the water from traveling downstream a. water collects behind the dam to form a reservoir = an artificial lake (like Dillon) b. water from the reservoir is used for drinking, manufacturing, and irrigation. c. can provide flood control and electricity d. dams also effect ecosystems: i. the reservoir floods dry land ecosystems. ii. ecosystems downstream are disrupted because they are now dryer.

D. Groundwater = water that seeps down through the soil and is stored underground 1. may be stored in aquifers a. these are underground rock formations usually made of rocks, sand and gravel with a lot of air spaces for water. b. occasionally may have areas without rock example: limestone caves full of water 2. may take millions of years to collect. 3. the land where groundwater comes from is called its recharge zone

4. Many cities and communities use groundwater. a. dig wells into aquifers and pump water out. b. in some places, groundwater is close to the surface and comes out in springs 5. Aquifers are running low a. people are pumping water out faster than it can be replaced b. the water level in many aquifers is dropping fast

E. Solutions to Groundwater Shortages 1. Desalting sea water = desalinization a. saltwater cannot be used for drinking or irrigation b. two main methods exist: i. distillation = heat evaporates the water leaving the salt behind ii. Reverse osmosis = pressure pushes water through a semi permeable membrane that does not allow salt through c. desalinization is very expensive

2. Towing water from one place to another a. towing icebergs is one possibility. i. Saudi Arabai experimented with towing these ii. problems: they are hard to tow; they melt quickly as they get near the equator; how do you transport it once it gets to shore? b. Alaska is experimenting with sending water south in plastic bags to sell.

3. Water Conservation – some examples: a. installing low-flow faucets and shower heads b. turning off tap water while brushing teeth and shaving c. water lawns at night to reduce water loss by evaporation d. people in desert areas are replacing their grass with native plants that need less water e. putting filled water bottles inside toilet tank to reduce the water used for each flush.