How long does water last?

AIM: How do we use water resources?

Independent Activity - 25 min - Students will use the resources on page 2 of their website to complete the following:

The length of time water spends in the groundwater portion of the hydrologic cycle may be as little as days, or as much as 10,000 years or more. This is called “residence time.”

For example: A raindrop may fall to the earth’s surface. It may seep down through the soil to a saturated zone or aquifer only to pumped back to the surface and sprayed from a garden hose and back down again.

Groundwater begins as rain or snow that falls to the ground. This is called precipitation. Only a small portion of this precipitation will become groundwater. Most will run off the land surface to become part of a stream, lake or other body of water. This water we call “surface water.” Some of the water is used by plants and returned to the atmosphere. This is called transpiration. Some of the water evaporates off the land to become water vapor once again.

The remaining precipitation seeps, or percolates into the earth to become “groundwater.” These actions make up the Hydrologic Cycle. Water is in a constant cycle of change, from one form to another. From liquid to vapor to ice or snow and back to a liquid state.

This same water from rain or snow continues down through the soil until it reaches an area that is saturated with water, and is called the “saturated zone.” Water in this saturated zone is called “groundwater”.

The point where water reaches the saturated zone is called the “water table”—because it is like a table top. Above is the unsaturated zone full of rocks, soil and earth that have let water seep down. Below is the saturated zone of groundwater. The saturated zone below the water table has water that fills the spaces (or pores) between rock particles or the cracks (fractures) of the rocks. This is where groundwater is found. This is where groundwater that you drink, bathe or use for daily chores comes from. We call this geologic area of groundwater an AQUIFER.

Part A: Water Resources:

Water Resources:

Which is the largest reservoir within the hydrologic cycle?

Which source of water has the lowest residence time?

Why does water residence time and water pollution matter to study?

•Water is a precious commodity.

• Nonetheless, in the U.S., we commonly take access to quality drinking water for granted, not to mention the availability of water for all other important activities including production of food and energy.

•And, this water presently comes to most people in the U.S. at a very low cost—just cents per gallon.

•We are, of course, privileged relative to other regions of the world, some of which do not have sufficient fresh water resources and where people may not even have access to safe drinking water supplies.

Part B: How much water does an individual HS student consume in a week?

To better understand their weekly water consumption, students will use the chart to reference a variety of actions and services that range in their water impact. After they compute their water consumption, they will use this data to complete the summary questions:

PART C:

According to the United States Geological Survey, it is estimated that each person uses about 80-100 gallons of water per day or 560-700 gallons per week. This number is an average and may be higher in places that are dry and hot. Answer the following questions to determine whether your use of water at home is average or needs to be adjusted.

If your water usage is above average, what was the largest source of water usage at your house? List three ways you could minimize the water usage of your largest water usage activity.
What is the municipal water source for your area (groundwater or surface water)?
What is the average water usage per person in your town or region?
Based on the number of people living in your house, how many gallons per week does your fam

PART D: Explore the Maps below and then Watch the VOX news video at the bottom

For the last 10 years, the USA has been experiencing a greater drought among Western States that serve millions of people in Urban areas.

PART D

PART D: Using the Video Resource from VOX

What are 3 factors contributing to the drought of the western USA?
What can be done to help mitigate the water shortage?

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