Lesson Plans: Coastal Erosion
Objective
The objective of this activity is to study the coastal erosion (or deposition) by waves and sea level rise at a particular area.
Materials
Each student or group of students will need the following:
- Graph paper
- Ruler
- Pencil and pen
Important Points to Understand
To observe changes in sea level, scientists regularly measure the sea level at certain places. If they want to predict what will happen to sea level in the future, say at a particular beach, they look at the past trends.
Has sea level at this beach been rising or falling over the past years? Has the beach sand been eroded by rising sea level or accumulated because of falling sea level?
Preparation
Try to explain that the information in the table below shows a study of estimated
volume of sand on a part of the beach at Lefaga, Samoa.
| Year | 1972 | 1973 | 1974 | 1975 | 1976 |
| Sand Volume (m3) | 268 | 331 | 192 | 394 | 201 |
| Year | 1977 | 1978 | 1979 | 1980 | 1981 |
| Sand Volume (m3) | 185 | 386 | 252 | 323 | 351 |
| Year | 1982 | 1983 | 1984 | 1985 | 1986 |
| Sand Volume (m3) | 364 | 385 | 343 | 349 | 377 |
Procedure
- Plot the data on a graph paper, time in years on the horizontal axis and the volume of sand on the vertical axis.
- Try to understand the zigzag character of the graph.
Questions
With the graph, try to answer the following questions:
- Which years showed erosion and which years showed deposition?
- Can you predict what will happen to the beach over a long period of time
(e.g., 50 years) from these data?
