Erosion Lab
Collaborators:
Sam Freeman, Ethan Lee, Ryan Baldwin, Michael Goss
Abstract:
In order to test how grass and ground cover affect erosion, an experiment was conducted. The experiment involved three bottles of soil, one with grass, one with pebbles, and one with soil only. 100 mL of water was poured in each bottle and the amount of water that flowed out was measured, as well as the time it took to flow. It was found that 65 mL of water came out of the soil only bottle while only 41 mL came out of the grass one, meaning the grass absorbed the most water. Also, the water took only 8 seconds to flow through the grass bottle and 23 to flow through the soil only bottle. Furthermore, the water collected from the grass bottle was relatively clear compared to the other two bottles, with the soil only bottle having the muddiest water.
Problem:
Wild-again.org states that "when the ground surface is stripped of vegetation," (which is the result of deforestation and development), "the upper soils are vulnerable to both wind and water erosion." What are the effects of grass or vegetation in general on the movement of water in an ecosystem?
Hypothesis:
If 100 mL of water is poured in three different bottles of soil, one with grass, one with ground cover, and one plain, then the least amount of water will take longest to pass through the one with grass, followed by the one with the ground cover which will take slightly less time for slightly more water to pass through. Furthermore, the water from the bottle with grass will be the cleanest while the water from the bottle with no cover will be the muddiest.
Parts of the Experiment:
The Independent variable was the type of (or lack of) material on top of the soil and the dependent variables were the amount of water collected, the time it took for the water to stop flowing, and qualitative observations like color and density. The experimental group was the bottle with the vegetation in it and the bottle with the groundcover and the control group was the bottle with just soil.
Materials:
Three 2 liter bottles, scissors or a knife, potting soil, grass seed, water, gravel or leaf litter, beakers, graduated cylinder
Methods:
1. Cut three 2 liter bottles in half.
2. Place soil in the bottles.
3. Spread grass seed through one of the bottles' soil.
4. Water the seed every 3-4 days and make sure the bottle is under light. Do this until the grass grows 2-4 inches tall. If the grass grows higher than this (pictured below), cut it.
Collaborators:
Sam Freeman, Ethan Lee, Ryan Baldwin, Michael Goss
Abstract:
In order to test how grass and ground cover affect erosion, an experiment was conducted. The experiment involved three bottles of soil, one with grass, one with pebbles, and one with soil only. 100 mL of water was poured in each bottle and the amount of water that flowed out was measured, as well as the time it took to flow. It was found that 65 mL of water came out of the soil only bottle while only 41 mL came out of the grass one, meaning the grass absorbed the most water. Also, the water took only 8 seconds to flow through the grass bottle and 23 to flow through the soil only bottle. Furthermore, the water collected from the grass bottle was relatively clear compared to the other two bottles, with the soil only bottle having the muddiest water.
Problem:
Wild-again.org states that "when the ground surface is stripped of vegetation," (which is the result of deforestation and development), "the upper soils are vulnerable to both wind and water erosion." What are the effects of grass or vegetation in general on the movement of water in an ecosystem?
Hypothesis:
If 100 mL of water is poured in three different bottles of soil, one with grass, one with ground cover, and one plain, then the least amount of water will take longest to pass through the one with grass, followed by the one with the ground cover which will take slightly less time for slightly more water to pass through. Furthermore, the water from the bottle with grass will be the cleanest while the water from the bottle with no cover will be the muddiest.
Parts of the Experiment:
The Independent variable was the type of (or lack of) material on top of the soil and the dependent variables were the amount of water collected, the time it took for the water to stop flowing, and qualitative observations like color and density. The experimental group was the bottle with the vegetation in it and the bottle with the groundcover and the control group was the bottle with just soil.
Materials:
Three 2 liter bottles, scissors or a knife, potting soil, grass seed, water, gravel or leaf litter, beakers, graduated cylinder
Methods:
1. Cut three 2 liter bottles in half.
2. Place soil in the bottles.
3. Spread grass seed through one of the bottles' soil.
4. Water the seed every 3-4 days and make sure the bottle is under light. Do this until the grass grows 2-4 inches tall. If the grass grows higher than this (pictured below), cut it.
5. Cover one of the remaining bottles with either leaf litter or gravel.
6. Place the three bottles on an elevated surface and place empty beakers underneath the mouth. At this point, the experiment should look something like this.
6. Place the three bottles on an elevated surface and place empty beakers underneath the mouth. At this point, the experiment should look something like this.
7. Prepare a graduated cylinder with 100 mL of water in it.
8. Pour the water in one of the bottles while being sure to record the time, amount, and color of the discharged water. Do this for each bottle.
Data:
8. Pour the water in one of the bottles while being sure to record the time, amount, and color of the discharged water. Do this for each bottle.
Data:
Furthermore, it is to be noted that the collected water from the bottle with just soil was very muddy while the one with ground cover was a little less and the one with grass was pretty much clear.
Data Analysis:
According to the data, a significantly larger amount of water is collected from just the soil bottle than in the other two bottles, which are about the same at 41 and 43. This means that the grass and ground cover are better at absorbing more water than just the soil alone. Furthermore, the data shows that the bottles with ground cover and soil only take the longest for the water to stop flowing, meaning they are the best at absorbing water quickly but, in the case of the soil only bottle, not holding the water very long. As for the grass bottle, it appears that a relatively large amount of the water is quickly absorbed which causes it to stop flowing quickly.
Conclusion:
As predicted in the hypothesis, the most water was collected from the soil only bottle (65 mL) and the least from the grass bottle (41 mL). Also, the water from the soil only bottle was the muddiest while the water from the grass one was pretty clear. The water from the ground cover bottle was somewhere in between. This indicates that grass/vegetation is best at preventing erosion because only a small amount of soil is being carried along with the water, in contrast with how it was for just the soil and also for the ground cover to a lesser extent. Using this logic, after an area was deforested, it would be best to plant grass seed to prevent erosion, although leaving the rotting material behind wouldn't be that bad. What would be very bad and cause the area to experience a dangerous amount of erosion would be leaving bare soil. This is evident by the large amount of water collected (65 mL) and how muddy the water was. Another good thing about grass/vegetation as compared to ground cover and regular soil is that grass naturally filters water and takes out pollutants when it absorbs the water. This is a natural service of grass and does not happen with pebbles or just soil.
The data for the time it took the water to flow has not been mentioned because it is suspected to be invalid. It just makes sense that, if grass can absorb the water best, it would take the longest to flow. Likewise, if soil only is bad at absorbing water, it shouldn't have taken so long to flow. The reason for this inaccuracy is probably the result of an experimental error or just the subjectivity of determining when the water has actually stopped flowing. If the experiment was redone, some specifications regarding what it is classified as "running water" would need to be made. Also, it would be interesting to do the lab on a larger scale to test the effects over a longer period of time. This would mean perhaps actually measuring the amount of dirt used and recording how much dirt erodes as larger and larger amounts of water are poured onto the different types of bottles.
Citations:
"Erosion and Flooding." Wild-again.org. N.p., n.d. Web. 13 Nov. 2013. <http://wild-again.org/UKsite/Erosion-flooding-UK.html>.
According to the data, a significantly larger amount of water is collected from just the soil bottle than in the other two bottles, which are about the same at 41 and 43. This means that the grass and ground cover are better at absorbing more water than just the soil alone. Furthermore, the data shows that the bottles with ground cover and soil only take the longest for the water to stop flowing, meaning they are the best at absorbing water quickly but, in the case of the soil only bottle, not holding the water very long. As for the grass bottle, it appears that a relatively large amount of the water is quickly absorbed which causes it to stop flowing quickly.
Conclusion:
As predicted in the hypothesis, the most water was collected from the soil only bottle (65 mL) and the least from the grass bottle (41 mL). Also, the water from the soil only bottle was the muddiest while the water from the grass one was pretty clear. The water from the ground cover bottle was somewhere in between. This indicates that grass/vegetation is best at preventing erosion because only a small amount of soil is being carried along with the water, in contrast with how it was for just the soil and also for the ground cover to a lesser extent. Using this logic, after an area was deforested, it would be best to plant grass seed to prevent erosion, although leaving the rotting material behind wouldn't be that bad. What would be very bad and cause the area to experience a dangerous amount of erosion would be leaving bare soil. This is evident by the large amount of water collected (65 mL) and how muddy the water was. Another good thing about grass/vegetation as compared to ground cover and regular soil is that grass naturally filters water and takes out pollutants when it absorbs the water. This is a natural service of grass and does not happen with pebbles or just soil.
The data for the time it took the water to flow has not been mentioned because it is suspected to be invalid. It just makes sense that, if grass can absorb the water best, it would take the longest to flow. Likewise, if soil only is bad at absorbing water, it shouldn't have taken so long to flow. The reason for this inaccuracy is probably the result of an experimental error or just the subjectivity of determining when the water has actually stopped flowing. If the experiment was redone, some specifications regarding what it is classified as "running water" would need to be made. Also, it would be interesting to do the lab on a larger scale to test the effects over a longer period of time. This would mean perhaps actually measuring the amount of dirt used and recording how much dirt erodes as larger and larger amounts of water are poured onto the different types of bottles.
Citations:
"Erosion and Flooding." Wild-again.org. N.p., n.d. Web. 13 Nov. 2013. <http://wild-again.org/UKsite/Erosion-flooding-UK.html>.