Erosion Lab Report
Collaborators: Julianne Rodgers, Logan Shytle, Christina Filippini
Introduction:
The Erosion Lab tests how vegetation affects runoff and erosion in a particular ecosystem. "Grassed filter strips in farm fields help reduce runoff and erosion by slowing water velocities in the vegetated areas. Grassy strips also reduce erosion by trapping excess sediment, nutrients, and farm chemicals" (Meyer). When grass is present in an ecosystem, the area is found to have less erosion than an area without grass. This is because grass can serve as a buffer zone. Buffer zones, also known as riparian zones, are the areas between land and a river or stream. These areas provide a barrier, preventing rain from washing soil, sediment, fertilizers and other materials from the land into the water. The buffer zones catch the materials before they reach the water. These zones are regulated along stream and lakes because if the material washes into the water it could alter the ecosystems negatively. For example, fertilizers washing into the water from nearby homes or farms could cause eutrophication in streams and rivers, causing more algae to grow and killing the fish that lived there.
Hypothesis:
If grass is present in an ecosystem, then the movement of water will be slower and the erosion will be less than ecosystems without grass with only soil and soil and pebbles because grass serves as a buffer in an ecosystem.
Parts of the Experiment:
Experimental Group: Bottle with the grass and bottle with the soil and pebble combination
Control Group: Bottle containing only soil
Independent Variable: Type of "ground" in each bottle
Dependent Variable: The movement of water and the amount of erosion
Control: amount of sunlight each bottle was exposed to, size of bottle, amount of water used
Control Group: Bottle containing only soil
Independent Variable: Type of "ground" in each bottle
Dependent Variable: The movement of water and the amount of erosion
Control: amount of sunlight each bottle was exposed to, size of bottle, amount of water used
Materials:
- Three 2-liter bottles, cut in half
- Potting soil
- Grass seed
- Water
- Pebbles, gravel or leaf litter (this experiment used pebbles)
- Graduated cylinder
- Beaker
- Books/other materials to create an incline
- Timer
Method:
Growing the Grass:
1) Place soil in an empty 2-liter bottle that has been cut in half. Spread grass seed evenly throughout the soil.
2)Water grass seed every 3-4 days and allow it to sit near a source of sunlight or under a plant grow lamp. The grass from this experiment sat near a window.
Testing the Effects:
1) When the grass has grown 2-4 inches in height, it is time to test the effects.
2) Fill two more empty 2-liter bottles with soil. Cover one with a top cover of your choice (this experiment used pebbles) and leave the soil bottle as a control
3) Place one of the bottles up on top of an elevated surface. Place an empty beaker underneath the mouth of the bottle.
4) Fill a graduated cylinder with 100mL of water.
5) Have a student start a timer and say "GO". When the timer says go, pour the water into the soil/grass.
6)Record the time, amount, and color of the water discharge in the table below.
7) Repeat for the other two bottles.
1) Place soil in an empty 2-liter bottle that has been cut in half. Spread grass seed evenly throughout the soil.
2)Water grass seed every 3-4 days and allow it to sit near a source of sunlight or under a plant grow lamp. The grass from this experiment sat near a window.
Testing the Effects:
1) When the grass has grown 2-4 inches in height, it is time to test the effects.
2) Fill two more empty 2-liter bottles with soil. Cover one with a top cover of your choice (this experiment used pebbles) and leave the soil bottle as a control
3) Place one of the bottles up on top of an elevated surface. Place an empty beaker underneath the mouth of the bottle.
4) Fill a graduated cylinder with 100mL of water.
5) Have a student start a timer and say "GO". When the timer says go, pour the water into the soil/grass.
6)Record the time, amount, and color of the water discharge in the table below.
7) Repeat for the other two bottles.
Data:
Data Analysis:
The data found after completing the Erosion Lab supports the hypothesis "If grass is present in an ecosystem, then the movement of water will be slower and the erosion will be less than ecosystems without grass with only soil and soil and pebbles because grass serves as a buffer in an ecosystem." As can be seen in the data table above, when 100 mL of water was poured into the grass bottle, only 20mL of water was collected in the beaker below as runoff. This amount is less than both the soil and pebbles bottle, and the soil only bottle which had 60 mL and 40 mL of runoff respectively. The runoff from the grass was also the clearest, containing only a few, small pieces of soil compared to the other two samples, where the runoff changed color due to the amount of soil and other materials in the water.
The change in the amount of runoff was caused by the different types of "grounds". When the water was poured into the bottle with grass, the grass "caught" most of the water, leaving little to run off into the beaker. Additionally, the roots of the grass prevented the water from washing away the soil, allowing for a clearer runoff. The plain soil bottle had less runoff than the soil and pebbles bottle, although both had more runoff then the grass bottle, because when the water was poured into the soil bottle, some of the water was absorbed into the soil before running off and reaching the beaker. However, with the pebble and soil combination, the pebbles prevented the water from absorbing into the soil, and there was no grass or roots to "catch" the water before running off into the beaker.
The different types of "ground" also affected the amount of time it took for the water to go through each bottle and stop dripping into each ecosystem. The water from the grass bottle only ran off for 12 seconds. This is because the grass slowed, and eventually stopped, the flow of water through the bottle. Whereas in the soil and pebble bottle, taking 46 seconds, the pebbles did little to slow the flow of water. The soil bottle, taking 20 seconds, was only slowed by the dryness of the soil. The dryness of the soil, could be considered an error because if the conditions of the soil were different, the water may have flowed for longer before being absorbed.
The change in the amount of runoff was caused by the different types of "grounds". When the water was poured into the bottle with grass, the grass "caught" most of the water, leaving little to run off into the beaker. Additionally, the roots of the grass prevented the water from washing away the soil, allowing for a clearer runoff. The plain soil bottle had less runoff than the soil and pebbles bottle, although both had more runoff then the grass bottle, because when the water was poured into the soil bottle, some of the water was absorbed into the soil before running off and reaching the beaker. However, with the pebble and soil combination, the pebbles prevented the water from absorbing into the soil, and there was no grass or roots to "catch" the water before running off into the beaker.
The different types of "ground" also affected the amount of time it took for the water to go through each bottle and stop dripping into each ecosystem. The water from the grass bottle only ran off for 12 seconds. This is because the grass slowed, and eventually stopped, the flow of water through the bottle. Whereas in the soil and pebble bottle, taking 46 seconds, the pebbles did little to slow the flow of water. The soil bottle, taking 20 seconds, was only slowed by the dryness of the soil. The dryness of the soil, could be considered an error because if the conditions of the soil were different, the water may have flowed for longer before being absorbed.
Conclusion:
Using this experiment as an example, after deforestation it would be best to leaving and/or planting vegetation to reduce runoff compared to leaving pebbles or leaving bare soil. According to the data collected from this experiment, grass or vegetation does the best at slowing water flow, and preventing erosion and runoff. The grass bottle only had 20 mL of runoff, and the majority of that runoff was clear water, with only a few soil pieces. Compared to the pebble and soil and the soil bottle which had 60 mL and 40 mL of runoff respectively, and a brown colored water due to the amount of soil in it, the grass provides a better buffer against erosion. The grass would also allow for the greatest chance of water filtration, seeing as the water was mostly clear except for a few soil pieces. Perhaps if the grass was thicker, or if there was more grass in the bottle, there would have been even less soil in the beaker because there would have been more roots to hold on to it.
To do this lab on a larger scale to test the effects over a longer period of time scientists could go to a local stream or river and choose different locations on the stream or river to plant different types of vegetation and cover the land with either pebbles and soil or just soil. Scientists could then record the rainfall and make observations on the erosion of the land. Scientists could also take observations about the environment around the stream to see how that affects the erosion and how erosion affects the environment.
Through this experiment, it can be seen that without buffer zones, or areas that are found between land and water, soil erosion will occur as seen with the runoff in the beaker and water pollution will occur, as seen with the change in water color.
To do this lab on a larger scale to test the effects over a longer period of time scientists could go to a local stream or river and choose different locations on the stream or river to plant different types of vegetation and cover the land with either pebbles and soil or just soil. Scientists could then record the rainfall and make observations on the erosion of the land. Scientists could also take observations about the environment around the stream to see how that affects the erosion and how erosion affects the environment.
Through this experiment, it can be seen that without buffer zones, or areas that are found between land and water, soil erosion will occur as seen with the runoff in the beaker and water pollution will occur, as seen with the change in water color.
Works Cited:
Meyer, Grant A. "Water Encyclopedia." Runoff,
Factors Affecting. Advameg, Inc, n.d. Web. 31 Mar. 2015.
<http://www.waterencyclopedia.com/Re-St/Runoff-Factors-Affecting.html>.