Water Movement in the Earth

Lab investigation into Permeability and Porosity

Permeability

• The capacity of rock to transmit a liquid. (This relates to the size and shape of rock pores along with how the pores are connected.)

Porosity

• How much space is in between rock particles. The space may be compared to the total volume of the rock.

This lab is divided into three parts:

• Part I - How Pore Space Varies with Size of Particles

• Part II - How Permeability Varies with Size of Particles

• Part III - How Porosity Varies with Soil Type

In parts I and II you will use:

• 4mm beads

• 7mm beads

• 12mm beads

In part III you will use three soil types:

• Black dirt

• Sand

• gravel

How Pore Space Varies with Size of Particles

• Measure how much water (in ml) it takes to cover all the beads in the tube. (Make sure the clamp is closed.)

• Record your data.• Repeat this process for

all three bead sizes.

How Permeability Varies with Size of Particles

• Pour into the tube 270 ml of water.

• Time how long it takes for the water to empty the tube.

• Record your data.• Repeat this process for

all three bead sizes.

How Porosity Varies with Soil Type

• Place filter paper in the bottom of a cone.

• Weigh out 100 g of dry soil. (Include the cone’s weight.)

• Slowly add 40 ml of water to the soil.

• After draining, weigh the cone and the soil.

continued

• Record the weight of the soil with the water.

• Record the volume of water retained by the soil. (HINT: 1ml of water = 1g of water.)

• Repeat this process for all three soil types.

CLEAN UP!

• Make sure all water is emptied.

• Make sure the area is dry.

• All equipment is in the proper area.

• Make sure to throw the filter paper away.

• Wet soils are put in the proper bucket.

• The lab tables are clean.

Graphs

• Remember the following on all your graphs:– Title, appropriate and specific– Label each axis, including units– The scale needs to fit the paper– Neatness is important– Write a conclusion for each graph on the back

of your paper

How Pore Space Varies with Size Particles

• Bead size (mm) versus amount of water needed to cover beads (ml)

240

250

260

270

280

290

300

4mm 7mm 12mm

ml

How Permeability Varies with Size of Particles

• Bead size (mm) versus time for 270 ml of water to drain (seconds)

0

2

4

6

8

10

12

14

4mm 7mm 12mm

seconds

How Porosity Varies with Soil Type

• Soil type versus the volume of water held by soil (ml)

0

5

10

15

20

25

30

35

40

black dirt sand gravel

grams