PLEASE READ• On many days, when you come into class, there

will be a DAILY QUESTION on the board or screen.

• If there is a DQ, get out a piece of lined, hole-punched paper and begin writing a response. Put your name on the paper and date the response. No need to rewrite the question. 5 minutes or less

• Start a new response right below where the last one ended. I will collect DQs periodically.

DAILY QUESTION

• Give a specific example of The Tragedy of the Commons and explain how it has come about.

• Do not repeat examples we’ve used in class, and be specific—no ``wood in the rainforest.’’

Freshwater resources:

use and conservation

Where is the

water?

http://ga.water.usgs.gov/edu/watercycle.html

Hydrologic cycle

• Water you drink today may have been part of a dinosaur’s urine 75 million years ago.

• OR, in the Passaic River 4 months ago

residence times– Range from days in the atmosphere to

thousands of years deep in the ground

Rivers

• Rivers have a beginning: SOURCE

• And an end: MOUTH

• Little rivers that feed into bigger rivers (and make them bigger) are TRIBUTARIES

Main rivertributary

Lakes

• Non-flowing surface water

• Numerous zones:

Watershed

• Warning: sometimes confusing

• Watershed is the area of land drained by a river and its tributaries

• What Is A Watershed?

Groundwater

• Not ``an underground lake’’

• Most groundwater is in aquifers.– Water in the pore spaces of rock, sand, or

gravel.

•

•

Aquifers

• Recharge zone– Area of the Earth’s surface where water

percolates down into (infiltrates) the Earth and resupplies the aquifer.

• Why is a recharge zone important?

• How would you measure the rate of an aquifer’s depletion? (can you state a simple word equation)?

• What might influence the rate of recharge?

How do we use water?

• Consumptive use: water removed from aquifer or surface is not returned directly to that body.

• Nonconsumptive use: water is not removed, or is only temporarily removed from the source

Uses of water

• What do you think are the major uses of water in the United States?– In other words, how do we use the water that is

withdrawn from aquifers, rivers, and lakes?