Get the Ground Water Picture



Get the Ground Water Picture

Warm up

Hydrologists study wells to learn the types of rock located below ground. Draw pictures representing what you think it looks like underground (texture and color of rock formations) or write a brief description of what happens to water after it seeps into the ground.

The Activity

Part I

Ground water demonstration

Part II

1. Hand out strips numbered 2 – 24 and copies of the Well Log Data Chart. The paper represents the length of a well that has been dug. You will receive data about the location and types of rock materials in your wells and transfer this information to the strips of paper to make well logs.

2. Fill in the log based on the number on the strip of paper (if the strip is labeled 6, then use data from Well #6) and the information in the Well Log Data Chart. BE sure to note the land use existing above the well sites.

3. When you have completed your log, answer the questions based on your well logs.

a. The horizontal scale of the cross section is 1 inch = 1 mile. The vertical scale is 1 inch = 50 feet. How many miles are horizontally represented in the cross section? How many feet are vertically represented in the cross section?

b. How many feet below the surface is the water table?

c. Imagine a drop of water falling on the surface above your well. What pollutants might this drop of water pick up as it filters into the ground?

d. Describe the drop’s movement down the column. Through which layers would it move the fastest? The slowest?

e. At which layer might the drop’s movement be restricted? Remember the only a slight amount of water would pass through the clay. What might the source of water under the clay level (in the gravel level) be?

4. Assemble your well logs in order, and tape them to the paper provided. Look at the Ground Water Student Page. Compare your well logs cross-section to those on the chart.

a. Using the vocabulary, locate the different parts of a ground water system on the Well Log Ground Water Chart (Cross-Section).

b. What direction is the ground water moving in the unconfined aquifer?

c. What are water sources for the unconfined aquifer?

d. How long would it take the water in the sandstone formation to move from Well #1 to Well #15?

e. Now that you know about the land use above the well sites, and the direction water flows, how would you answer question 4c?

f. Refer to the Ground Water System (Simplified). What are possible sources of water in the confined aquifer portion of your well?

Vocabulary

• Water Table:

The top of an unconfined aquifer; indicates the level below which soil and rock are saturated with water.

• Confined Aquifer:

An aquifer that is bounded above and below by nonpermeable layers that transmit water significantly more slowly that the aquifer. The water level in a well that taps a confined aquifer will rise above the top of the aquifer because the confined aquifer is under pressure. Also called artesian aquifer.

• Unconfined Aquifer:

An aquifer in which the upper boundary is the top of the water table

• Permeable Layer:

Portion of aquifer that contains porous rock materials that allow water to penetrate freely

• Impermeable Layer:

Portion of aquifer that contains rock material that does not allow water to penetrate; often forms the base of unconfined aquifers and the boundaries for confined aquifers.

• Zone of Saturation

The part of a water-bearing formation in which all spaces (between soil particles and in rock structures) are filled with water

• Zone of Aeration

Portion of unconfined aquifer above the water table where the pore spaces among soil particles and rock formations are filled with air

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