Upload
guillermo-werth
View
216
Download
0
Tags:
Embed Size (px)
Citation preview
Water Resources & the Technologies We Use to Harness Them
Water TechnologiesThinking with Data: Science Part 2
Discussion Question
Why is water necessary for life?
Discussion Question
What percentage of all of the water on earth is fresh water?
What is the Trend in Global Use of Our Fresh Water?
Where Do We Get Our Fresh Water?
Discussion Questions
If most of the surface water is in lakes and rivers, how can we get the water to places
where people live and grow crops?
And, if most of the available water is stored underground, how can we get that water to
the surface so we can use it?
Dams
What Dams Do
• Store water during the rainy season
• Control periodic floods
What Dams Do• Produce electrical energy
http://earthsci.org/mineral/energy/hydro/hydroplant-animate.gif
What Dams Do
• Provide recreation areas (fishing, boating)• Redirect river water to new locations for farming
and domestic use
Discussion Questions
What do you think are the most important uses of dams?
Do you think that dams can cause any problems? If so, what might they be?
Problems Caused by Dams
• Dams change the pattern of the rivers’ natural cycles. The new patterns may not provide the food and shelter needs of the plants and animals living there.
Dams stop flooding. What kind of problems might occur if floods are
stopped?
Discussion Question
Problems Caused by Dams• Floods take nutrients from the land to the rivers.• Animals who live in or by the water often
coordinate their reproductive cycles with flood seasons so their young have food to live.
Problems Caused by Dams• Floods also deposit rich silt onto the flood plains,
creating nutrient rich land for agriculture.
Silt
• Silt consists of very small particles of dirt and rock. Normal river water carries silt.
• When river water is trapped by a dam, the silt is deposited on the bottom and builds up behind the dam.
• The water released by the dam has no silt.
Normal silt
Silt is trapped and builds up behind the dam. The water released
by the dam is without silt.
Problems Caused by Dams
• If the dam releases water once in a while, the high energy and coldness of the sudden floods picks up and removes silt, sand, small animals, and woody debris. A healthy living river needs the sediment and warmth to provide a habitat for animals.
www.naturalsciences.org/.../River%20Otters.jpg
Discussion Question
Is it better or worse to have dams?
Before we look at the technologies designed to get our fresh water to the
people and the places it needs to go, let us take a closer look atour major source of fresh water -
groundwater
What is Groundwater?
http://groundwater.sdsu.edu/groundwater_utilization_and_sustainability_01.jpg
Wells
What Wells Do
• Tap groundwater for drinking and irrigation.
Problems With Wells
• Wells may deplete a nonrenewable source of groundwater.
• If the groundwater that the well is drawing from is contaminated, the water used for drinking or agricultural will also be contaminated.
Irrigation Canals
Discussion Question
What kinds of problems might interfere with us having all of the fresh, clean water that we need?
What Can Cause Problems With Our Current Water Supplies?
• Water Availability– Uneven distribution of water resources– Changing (and growing) population – Dams– Different climates in different regions
• Water Sharing– Who decides what is fair?
• Water Pollution– Salinity– Industrial pollution– Urban stormwater sewage– Shipping– Mining– Agricultural