Erosion Lab
Collaborators- Sam Freeman, Ryan Baldwin, Michael Goss, Griffin Matthews
Abstract- An experiment was conducted to test how different ground coverings affected soil erosion. In preparation for this lab, grass was planted and grown several weeks prior to the lab, to ensure that the grass was fully matured and could serve it's purpose in this lab. In this experiment, there were three types of coverage: grass, gravel, and no coverage as the control. When water was poured over the soil, the amount of water absorbed and the time it took to flow were recorded and compared. The grass absorbed the least water and took the shortest to flow, gravel did not absorb a whole lot of water and took a decent time to flow, while bare soil absorbed the most water and flowed the longest. Afterwards, turbidity of the resulting runoff was observed. Grass had the most clear water, while bare soil bad very dark and murky water.
Problem- According to National Geographic (1), nature has many ways to erode materials: freezing, washing, tumbling, scratching, melting, and using chemicals. However, this in this lab, using water on mock environments, you must find the answer to this question: How do different environments and ground coverings affect hydrologic erosion?
Hypothesis- If there is any ground covering, less soil will be eroded away because it will hold the soil in place or will prevent water from getting to the soil. This should apply most when grass or other plants are holding it down.
Parts of the Experiment- Control- Bare soil
Experimental- The different types of ground coverings
Independent- Ground coverings
Dependent- Amount of soil eroded
Materials- 2 liter bottles that are cut in half
Potting soil
Grass seed
Water
Pebbles/Gravel
100 ml graduated cylinder
100 ml beaker
Methods- 1. Cut 3 2 liter bottles in half the long way.
2. Fill one with potting soil and plant grass seeds in it.
3. Water it and let the grass grow for several weeks.
4. Fill the other two bottles with potting soil.
5. Cover the soil of one bottle with gravel and leave the other bare.
6. Line the three bottles up on top of an elevated surface. Place an empty beaker underneath the mouth of each bottle.
7. Prepare 3 graduated cylinders with 100 mL of water in each.
8. Have a student start a timer and say “GO.” When the timer says go, all 3 graduated cylinders should be poured onto the soil bottles.
9. Record the time, amount, and color of the water discharge in the table below. Then, answer the questions.
Abstract- An experiment was conducted to test how different ground coverings affected soil erosion. In preparation for this lab, grass was planted and grown several weeks prior to the lab, to ensure that the grass was fully matured and could serve it's purpose in this lab. In this experiment, there were three types of coverage: grass, gravel, and no coverage as the control. When water was poured over the soil, the amount of water absorbed and the time it took to flow were recorded and compared. The grass absorbed the least water and took the shortest to flow, gravel did not absorb a whole lot of water and took a decent time to flow, while bare soil absorbed the most water and flowed the longest. Afterwards, turbidity of the resulting runoff was observed. Grass had the most clear water, while bare soil bad very dark and murky water.
Problem- According to National Geographic (1), nature has many ways to erode materials: freezing, washing, tumbling, scratching, melting, and using chemicals. However, this in this lab, using water on mock environments, you must find the answer to this question: How do different environments and ground coverings affect hydrologic erosion?
Hypothesis- If there is any ground covering, less soil will be eroded away because it will hold the soil in place or will prevent water from getting to the soil. This should apply most when grass or other plants are holding it down.
Parts of the Experiment- Control- Bare soil
Experimental- The different types of ground coverings
Independent- Ground coverings
Dependent- Amount of soil eroded
Materials- 2 liter bottles that are cut in half
Potting soil
Grass seed
Water
Pebbles/Gravel
100 ml graduated cylinder
100 ml beaker
Methods- 1. Cut 3 2 liter bottles in half the long way.
2. Fill one with potting soil and plant grass seeds in it.
3. Water it and let the grass grow for several weeks.
4. Fill the other two bottles with potting soil.
5. Cover the soil of one bottle with gravel and leave the other bare.
6. Line the three bottles up on top of an elevated surface. Place an empty beaker underneath the mouth of each bottle.
7. Prepare 3 graduated cylinders with 100 mL of water in each.
8. Have a student start a timer and say “GO.” When the timer says go, all 3 graduated cylinders should be poured onto the soil bottles.
9. Record the time, amount, and color of the water discharge in the table below. Then, answer the questions.
Data-
Data Analysis- With their tipping angle and amount of soil exactly nearly the same, it seems that different ground coverings did influence erosion. Grass caused the least amount of erosion as it had the most clear water and had little dirt in the water. Gravel (groundcover) prevented a little erosion from happening, but dirt was still displaced by the water. Bare dirt however, was a very different story. With no covering, the dirt easily swept away and the remaining runoff had become a very dark brown, showing its yuckiness and the amount of dirt taken with it. With no covering, the most erosion occured and water became very polluted.
A very interesting part of the lab was the measuring of the amount of water runoff and time it took to flow. Grass, ironically, had the most runoff and shortest time. Gravel had the least runoff, but a decent time to stop flowing. The bare soil had a decent amount of runoff and took the longest time to stop flowing.
Conclusion- The experiment supported the hypothesis as the runoff water from the bottles with covering had less pollutants in them. The gravel kept the water from touching some of the soil and prevented it from washing away in the process. The grass, since it had grown for such a long time, had mature roots in the soil, keeping it in place as water ran over it. The roots also filtered out the water, taking out pollutants and impurities and keeping the water clear.
However, there was room for error in the lab. Since the grass had grown for such a long time, it was tall. Even after it was cut, it was still rather tall, perhaps too tall for this lab. The grass sample had not absorbed much water and took the least time to flow along with having the least pollutants in the runoff. Theoretically, the clear runoff was supposed to be through filtration, which take time, much more than 8 seconds. Even so, water would have also been absorbed by roots and soil in that process. Error could have occurred here in the pouring of the water, not on the soil, but in the blades of grass themselves. The water must have run across the blades, not touching the soil at all, and since the blades were so tall, they overlapped making a sort of blanket over the soil. This affected the time and amount of runoff. However, the resulting water quality would have been relatively the same.
Questions-
1. Describe the difference in the water collected from each of the 3 bottles.
Bare soil- 32.5 ml of water was collected
Gravel groundcover- 21.5 ml of water was collected
Grass- 66 ml of water was collected.
2. Using your data to support your answer, after deforestation, what would be most effective: planting grass seed, leaving rotting material behind, or leaving bare soil? Support your answer.
Planting grass seed would allow for the water to be collected as well as holding in the soil in place, preventing erosion. This way, it limits runoff and water pollution.
3. Which setting would allow the greatest chance of water filtration (for cleaning pollutants, etc)? Explain your answer.
Grass gave the best chance for filtration. The experiment showed that grass cover will hold in materials that water might pick up and allow for the resulting runoff to be clean.
4. Describe how this lab could be done on a larger scale to test the effects over a longer period of time. Give a complete description.
Disregarding laws and ethics, the lab could have been done on inclined slopes near different lakes with different types of ground cover along the slope. Samples of polluted water could have been poured into the different slopes and with that, the health and water quality of the lake could be monitored over a period of time to judge whether the ground coverings had held the soil and/or filtered the water.
Citations-
"Erosion and Weathering Sculpting Nature." National Geographic. National
Geographic, n.d. Web. 15 Nov. 2013.<http://science.nationalgeographic.com
/science/earth/the-dynamic-earth/weathering-erosion-article/>.
A very interesting part of the lab was the measuring of the amount of water runoff and time it took to flow. Grass, ironically, had the most runoff and shortest time. Gravel had the least runoff, but a decent time to stop flowing. The bare soil had a decent amount of runoff and took the longest time to stop flowing.
Conclusion- The experiment supported the hypothesis as the runoff water from the bottles with covering had less pollutants in them. The gravel kept the water from touching some of the soil and prevented it from washing away in the process. The grass, since it had grown for such a long time, had mature roots in the soil, keeping it in place as water ran over it. The roots also filtered out the water, taking out pollutants and impurities and keeping the water clear.
However, there was room for error in the lab. Since the grass had grown for such a long time, it was tall. Even after it was cut, it was still rather tall, perhaps too tall for this lab. The grass sample had not absorbed much water and took the least time to flow along with having the least pollutants in the runoff. Theoretically, the clear runoff was supposed to be through filtration, which take time, much more than 8 seconds. Even so, water would have also been absorbed by roots and soil in that process. Error could have occurred here in the pouring of the water, not on the soil, but in the blades of grass themselves. The water must have run across the blades, not touching the soil at all, and since the blades were so tall, they overlapped making a sort of blanket over the soil. This affected the time and amount of runoff. However, the resulting water quality would have been relatively the same.
Questions-
1. Describe the difference in the water collected from each of the 3 bottles.
Bare soil- 32.5 ml of water was collected
Gravel groundcover- 21.5 ml of water was collected
Grass- 66 ml of water was collected.
2. Using your data to support your answer, after deforestation, what would be most effective: planting grass seed, leaving rotting material behind, or leaving bare soil? Support your answer.
Planting grass seed would allow for the water to be collected as well as holding in the soil in place, preventing erosion. This way, it limits runoff and water pollution.
3. Which setting would allow the greatest chance of water filtration (for cleaning pollutants, etc)? Explain your answer.
Grass gave the best chance for filtration. The experiment showed that grass cover will hold in materials that water might pick up and allow for the resulting runoff to be clean.
4. Describe how this lab could be done on a larger scale to test the effects over a longer period of time. Give a complete description.
Disregarding laws and ethics, the lab could have been done on inclined slopes near different lakes with different types of ground cover along the slope. Samples of polluted water could have been poured into the different slopes and with that, the health and water quality of the lake could be monitored over a period of time to judge whether the ground coverings had held the soil and/or filtered the water.
Citations-
"Erosion and Weathering Sculpting Nature." National Geographic. National
Geographic, n.d. Web. 15 Nov. 2013.<http://science.nationalgeographic.com
/science/earth/the-dynamic-earth/weathering-erosion-article/>.