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