# 9 Measure the volume of erosion

Determine the volume of soil that has fallen into the ocean and give this number a real world comparison.

** **

Step 1

To calculate the volume, the height of the coastal plain must first be determined by someone measuring it on location.

In this area the height is approximately 2.2 meters. Now, calculate the volume. *See Hint 1 for a reminder of the formula for volume.*

* *

Researcher Benjamin Jones measures the height of a bluff on the north coast of Alaska. Photo courtesy Benjamin Jones and Christopher Arp, U.S. Geological Survey, Alaska Science Center.

- Roll-over for Hint 1:
- The formula for finding volume requires the measurement of all three sides of an object: length, width, and height. A good trick to remember how to find volume is to remember that volume has three dimensions. Area has two dimensions. In this case, the area (length and width) of the polygon was calculated by the ImageJ application in the previous activity.

**Answer:**
To find the volume of coastline lost, multiply the area in square meters by the height of the bluff, 2.2 meters. Volume = length x width x height.

In this example, the answer would be 1,130,400 m *Squared* x 2.2 m = 2,534,400 m *cubed*.

**Making Sense of the Number**

Measured by volume, the fourth-largest building in the world is the NASA Kennedy Space Center Vehicle Assembly Building (VAB), in Florida. The volume of the VAB is 3.6 million cubic meters (m3).

The total volume of soil eroded from this part of Cape Halkett between 1985 and 2005 was about 2.5 million m3. If the soil were put into the VAB, how much would it fill?

To find the answer, divide the volume of the soil by the volume of the building, 2,534,400 / 3,660,000.

What eroded off of the cape is equal to .69 or 69% of what the VAB could hold. If all the material that eroded were put into the VAB, it would be about two-thirds full.

NASA Kennedy Space Center photo.