Introduction: (Initial Observation)
Erosion is a group of natural processes, including weathering, dissolution, abrasion, corrosion, and transportation, by which material is worn away from the earth’s surface. Wind, rain, flood, temperature change and acid rain are among the natural causes for most erosions. Erosion can damage roads, bridges and fences. It can cause pollution of waterways and destroy stock when it occurs rapidly.
Erosion can be large enough to destroy cities and affect civilizations. There are many historical cities today, buried under ground and covered by sand or soil. These towns have been attacked by tornados, high winds or floods who carried mass of sands and eventually became inhabitant.
Erosion breaks large mountains and rocks and creates small sand particles. Sands will then move by high speed winds or flood to other areas, burying cities, forests and animals.
In this project we will investigate different methods that can be used to stop erosion.
Information Gathering:
Find out about causes of erosion and methods that have been used to control erosion. Read books, magazines or ask professionals who might know in order to learn about the causes or effects of erosion . Keep track of where you got your information from.
Visit http://www.geog.ouc.bc.ca/physgeog/contents/11g.html for a good description of erosion with a great vocabulary.
Additional Links:
Question/ Purpose:
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.
The purpose of this project is to explore methods of controlling erosion. Some of the specific questions that can be studied are:
- Does rain cause soil erosion?
- Do acidic rains cause erosion of rocks?
- Do streams weather rocks?
- Does icing cause erosion?
- Do vegetations reduce the erosion of soil?
- Do coatings reduce the erosion of limestone surfaces?
Identify Variables:
When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.
Depending on the question that you choose to study, you must define a separate set of variables. For example if you choose to find out if acidic rain cause erosion of rocks (question number 2), this is how you define your variables:
- Independent variable (also known as manipulated variable) is the acidity of rain. Possible values are none, low and high.
- Dependent variable is the rate of erosion. Erosion can be identified and measured in the form of weight loss in test samples.
- Controlled variable is the temperature
- Constants are the type of rock and the experiment procedures
Hypothesis:
Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis. You will need one hypothesis for each question that you choose to study.
For example this is a sample hypothesis for question number 2:
My hypothesis is that plants and vegetation can control the erosion of the soil.
and this is a sample hypothesis for question number 6:
Coatings and sealants are able to prevent or reduce erosion of rocks and stones.
Experiment Design:
Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”
Experiment 1:
What Happens To A Mountain?
Build a “mountain” of soil 50 cm high in an undisturbed location in your backyard. Observe the mountain once a week for three months. Measure its height and width and note any changes in its surface. After observing the mountain for an extended period of time, suggest what forces might have caused changes in your mountain. How long do you think the mountain would remain if you left it there?
To expedite the erosion, use a sprinkler to water your mountain.
Weathering – When rocks are worn down by water, wind, or other means, that is weathering. Soil is made up of weathered rock particles, so without weathering, there would be no soil. Try the following activities to see how rocks can weather.
Experiment 2:
How Do Chemicals Weather Rocks?
This experiment will show the effect of acid rain in erosion.
Place an equal number of limestone or marble chips in each of two jars. Cover the stones in one jar with water and those in the other with vinegar; then cover the jars. Allow the jars to stand overnight. You may notice some bubbles forming in the jar with the vinegar. (What type of gas is forming these bubbles?). The next day, pour out the liquid from each jar into separate bowls. Label the bowls “water” and “vinegar”. Allow the water in the bowls to evaporate. Compare the amount of solid material remaining in the two bowls.
The bowl that contained vinegar will have a larger amount of solid material. Limestone, marble, and other carbonate rocks react with acid to form carbon dioxide and soluble salts. Rainwater is often acid and can erode limestone easily. Acid groundwater dissolves limestone underground, forming caves and sinkholes. Study or visit any caves or sinkholes in your area. Examine other types of rock to see if they react to vinegar in the same way as carbonate rocks.
Experiment 3:
How Do Streams Weather Rocks?
Place some small, freshly broken pieces of rock or brick in a large plastic jar. Softer rocks such as sandstone, shale, or limestone work best. Fill the jar about halfway with clear water. Put aside some other pieces of the broken rock. Close the lid of the jar and shake it 1,000 times. Remove the rocks and note any changes in their appearance compared with the rocks that were not shaken. Describe these changes. Filter the water through a piece of filter paper or funnel lined with paper towels. What do you see in the filter paper? You may want to experiment with different types of rock to see what types will change more. What might happen to rocks in a stream? (Rocks in streams are weathered by water and movement.)
Experiment 4:
How Does Ice Weather Rocks?
Completely fill a glass jar with water and cap it tightly. Place the jar in a resealable plastic bag. Put the jar and the bag in a freezer overnight. When you remove the jar, it will be broken. Handle and dispose of the broken glass carefully. Explain what this experiment might tell us about rocks and weather. (When water freezes, it expands. When it freezes in cracks in rocks, the expansion can cause the rock to break.)
Erosion – When particles weathered from rocks are carried away, it is called erosion. Erosion is responsible for wearing down exposed places and depositing sediment in level places.
Experiment 5:
How Does Vegetation Affect Erosion?
Punch holes in the bottom of a plastic cup to make a sprinkler. Place three to five centimeters of soil in each of two planting flats. Sprinkle grass seed on the soil in one of them and cover lightly with soil. Water both flats every day with the sprinkler until the grass is five centimeters tall. Prop the ends of both flats up at a moderate angle with bricks or blocks. Sprinkle each flat with water equally until you observe soil erosion. In which tray did the soil erode more?
What might be the effect of removing plants like trees from a steep mountainside? How could soil erosion be controlled in steep places? What other factors can you think of that would affect the amount of erosion? Identify any areas in your community that are steep. Take a field trip to look for signs of erosion.
Experiment 6:
How Do coatings control erosion?
Introduction: Erosion caused by acid rain is a major cause of damage to the exterior of buildings, monuments and statues made of marble, limestone and metals. Parts of such erosions may be prevented by coating the material with a thin layer of protective material that are resistant to acidic solutions.
In this experiment will show the effect of acid rain in erosion and examine the effect of wax coatings on the reduction of erosion.
Procedure:
- Melt some paraffin wax (same material used to make candles) in a metal pan.
- Drop a number of limestone or marble chips in the hot wax.
- Remove the waxed gravels after a few seconds and let them cool off. Remove any extra wax so only a thin invisible layer will remain. Weight stones and place them in a jar.
- Place equal amount of of un-waxed limestone or marble chips in another jar.
- Cover the stones in both jars with vinegar; then cover the jars. Allow the jars to stand overnight. You may notice some bubbles forming in the jars.
- The next day, pour out the liquid from each jar into separate bowls. Label the bowls “waxed” and “un-waxed”.
- Allow the water in the bowls to evaporate.
- Weigh and compare the remaining waxed and un-waxed marbles separately and report their weight loss.
Materials and Equipment:
Can be extracted from the experiment section.
Results of Experiment (Observation):
Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.
Calculations:
For experiment number 6 you may calculate the rate of weight loss per hour (or per day) for the waxed and un-waxed stones.
Summary of Results:
Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.
It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.
Conclusion:
Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.
Sample conclusion:
Erosion is the loss of soil from the land. It is a process that is always occurring but it can happen faster if we misuse the land.
The rate of erosion can be increased by
- removing plant cover by burning pasture or felling trees, shelter belts or forests and by having too many animals on the land
- bad cultivation practices
- wind
- frost
- rain and water runoff and
- extreme climatic effects e.g. Cyclone Bola.
Related Questions & Answers:
What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.
Possible Errors:
If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.
If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.
References:
List of References
